THE best “how to set up” battery pack video out there! I spent years clarifying and watching other ppl do it! You won’t BELIEVE how many ppl don’t tell you the orientations the batteries or the voltage. They just say “oh spot weld or soldier”
i simply aded a switch cables battery clamps and a fuse with a converter .. i even learned that the one side of the converter has different stats when work.. melted some fuses . ruined some solders ... was epic .. .. when i was 8 . 26years ago my grandpa used to let me play with pcbs and even solder ,, burns and fumes didnt stop me!!!! hope my motivation returns !
I think it's actually priceless, because the feeling is completely separate from the cost. Which is not what quotations adds to the sentence... for anyone that needs to hear that.
I began refurbishing ebike batteries a while ago and figured it can be quite a profitable business. That welder you got, appears quite nice and works a lot better than many readymade ones that are available for cheap.
I will never buy a cheaper pre made e bike battery they are all horrible I don’t care what anyone says. Ride a eBay bought bike battery daily from 100-20% charge and it will be completely shot in months! After that mistake I bought all the tools and started making my own, 13s 8.8 ah battery cost $350 including the tools spot welder soldering gun etc but I’m using very good high drain cells. Most store bought batteries can’t handle a lot of current either, my pack can handle 90 amps continuous discharge and 20 amp charge rate. Not to mention you can use 21700 cells and get better watt hour to size/cost ratio. In the long run it’s beneficial because you have the tools and ability to make any battery whenever you need to fit any device. Have a lot of lifepo4 ups upgrades in the future.
I just use 2 multistar 6s 16000mah lipo packs in series. 12s rather than your 13, but that works fine with my bafang 750w midrive. It gives 35mph top speed, and in general use (at effort level 4 and me cycling) I get 35 miles range with that 16ah. Also extremely light - as both packs (giving me 12s 16ah) weight only 4kg. And the 2 packs cost me 120 pounds total. I already had a 10amp 6s charger for lipos. There's no protection from overdischarging of course, but the bike cuts off itself when too low. And the charger balances the cells. I've been using the same pack now for nearly 2 years, and have done around 1000 miles on them and they are still at full capacity.
Big benefit to DIY is knowing your pack is solid. Buying cheap modules can have poor results. Definitely a good idea to crack open what you bought if you can to see how good of a job they did inside.
I think the pro with making your own pack would be making it a larger capacity to the normal ones you buy off shelf. This pack is pretty small as it is. Good start though. Also picking up second hand cells is a good way of cutting costs, although adds risk of unreliability.
@@kevinhorstmann1435 No problem using used cells as long as you check them properly :) I bought a 8 channel tester/charger that tells me exact capacity of each cell
Great video. I wish it had been out a bit earlier because I made my own replacement battery Pack a few weeks ago. I also ordered the cells at accuteile. I soldered the nickel tape to the cells which is a pain in the ... . Theres one thing you might want to know: I realized the range at which the BMS turned off because of overdischarge was quite low. So I tried to get my head around it and realized that it might be due to short negative voltage peaks at the start of high power consumption (i.e accelerating). So I soldered a 1000uF support capacitor parallel to the output of the batterypack (i.e. the BMS). Et Voila: Range nearly doubled. I also created a range extender from the old cells which were ok according to capacity but just developed a higher inner resistance. I still try to figure out a good way to parallel the two packs safely. What I do right now is charge them both and then just connect them via a 10A fuse (which by the way blew twice already). Keep up the great work. I like the accent. I have the same (-;
I believe you should not connect in parallel two packs that are not the same (not same age in your case). When I want to balance batteries in parallel I connect them through a resistor initially, after a while I put smaller value resistor, you repeat that until you cannot see voltage across the resistor anymore which means no current so they are balanced.
Very nice! Finally a FIY or BUY video that really makes sense - most of the other ones only show what was the best alternative for you (the same doesn't apply to everyone - it depends on your knowledge and budget).
As a Old Ebike rat i was ready to pounce, but this was very well done. Just as a tip typical city traffic load is about 3Amps. max draw usually around 20-25 amp when full throttling from a stop. To extend battery life and range dramatically slowly accelerate Especially in city traffic there is often little need for going maximum velocity. I personally prefer Lead acids on my main workhorse though. I have a Li Ion as a backup. Never use below 12Ah you wont get far.
How would you compare this kind of pack to one based on RC lithium-polymer battery packs? I'm going to be working on an electric scooter project soon, and I was aiming for li-po batteries primarily because of their cost and relative ease of use.
lithium-polymer will be almost the same as far as the math goes compared to lithium ion. If you used packs you would probably want to use 3x 11.1v packs and 1x 14.8v pack in series to get to 13s.
Lipo isn't widely spread despite it's large current advantage in evs cause it has less charging cycles of longevity and is more volatile. Both li-ion and lifepo4 can supply enough current at any reasonable capacity, and lifepo4 has much larger range of operating temperatures.
LFP is the safest chemistry but needs a larger volume. Lithium polymer has the best energy capacity so is fine for small gadgets. It is too sensitive for heavy duty power especially with vibration in a bike or scooter. Not safe. Don’t go there.
You will find 1kw enjoyable for a brief moment. Then you want more. You will probably build an 5-10kw bike and enjoy it for a moment too. Then you will move into the heavier stuff and beat all the 450cc on the street while realising that you have spent 100x more money on the EV wave than the original budget. But in the end of the day it will all be worth it!
We need solid state batteries Tesla gonna start using if they not already We get the shit overstock or crap batches they pay bulk prices and get all good stuff shit bags 😂😂
The difference between DIY or BOUGHT battery packs is that by buying a ready made pack the cells are most likely the cheapest cells with the lowest amount of mAh & discharge rates, the BMS is one of the cheapest & light duty BMS's you could buy. If you are using a 13s Battery @ 54.6v @ 10amps 546w or 20amps 1092w or 30amps 1638w or 40amps 2184w electric motor then you will be draining such a high current from the battery pack that without knowing specifications of the battery pack it may not provide the power you really need. Plus most importantly lets say you only have a 1500w motor that requires 30amps continuous, if your battery can only supply 30amps maximum then your battery pack will overheat very quickly. To get around this you would need a battery pack that offers more amps maximum so that you are not putting much strain on the batteries. This is why most people who buy DIY rear wheels with much higher watts than standard will design their own DIY battery packs & specialty BMS with more features & greater control.
Is it on purpose @7:17, it's not complete yet cuz in regards to the right diagram which is in the sketch he showed @4:00 is supposed to be 3 of that 26 battery package he just created and so if I'll clarify you need 78 batteries in order to get a "48v 20ah 1000 watt battery pack"😉
this could not have come at a more perfect time. The same concepts here for a batter pack could be taken to more than just an e bike and i have been looking for a good explanation that really broke the process down for using li-ion cells.
You can't trust the cells you get on ebay but, labour cost is a major disadvantage (unless you class it as a hobby then its worthwhile) One point on the BMS, what's the balancing current? it's probably not very high.. so I'm wondering if there was a more severe voltage difference in the cells would the little passive balancing circuit cope with the charging current?
Yeah that's what I thought, even at 100mA I'd be a bit wary of some cells overcharging when series charging the pack.. I suppose some manual checks every now and then would suffice
I think the most important is the connection to the rest of the controllers of the bike. Most of the time, the BMS of the battery needs to talk to the controller unit of the bike. Then p.ex. the display of the bike can show the state of charge (SOC).
To be fair, if you used the same cells that those battery packs have, it would probably turn out much cheaper. You can't know what cells those have, could be some cheap Chinese ones.
Have you actually done measurements on what is their real mAh? Do you know how long/how many cycles it will last? No. With a good brand one you can pretty much know it won't give out after 10 cycles. Chinese stuff has way less quality control and even same batch batteries can have varying capacity or life.
Newjorciks tru but just like the chinese knife market, it has gone into a new world... Much better than before.. Tbh its safe to buy almost any 18650's.. just not the 9800mAh cells lll
All of it is from China. There is quality Chinese made products. And cheaply made products. simple as that I dislike when people say "cheap eBay crap" or "cheap Chinese stuff" What did you expect for little $
You need a special meter to measure it, if you hook it up to a multimeter, you will probably kill your multimeter. Mine is built in to my charger: www.amazon.com/Version-Digital-Battery-Discharger-Temperature/dp/B00ZGZZ40K/ref=sr_1_32?ie=UTF8&qid=1526094888&sr=8-32&keywords=lithium+charger www.walmart.com/ip/Tenergy-5-in-1-Intelligent-Cell-Meter-Capacity-Checker-Battery-Balancer-Battery-Discharger-Internal-Resistance-Tester-ESC-Servo-PPM-Tester/179864013?wmlspartner=wlpa&selectedSellerId=2240&adid=22222222227056692896&wl0=&wl1=g&wl2=c&wl3=233956535514&wl4=pla-384625138979&wl5=9022129&wl6=&wl7=&wl8=&wl9=pla&wl10=113146105&wl11=online&wl12=179864013&wl13=&veh=sem should do the job though.
Great scott, Hi Thank you so much, with the help of your videos i can deeply understand power electronics In my opinion , Without skilled hands education is useless Without kind heart education is dangerous Thanking almighty that you have both After watching your videos i feel that my skills are improving. Thank you again :) :)
@greatscott please post a link to the spot welder you got too, i get inspired by your videos and i am the the progress of making my own electric bike kit! Edit: i meant the one they sent you, not the diy one.
He has posted it in the description: " The spot welder that I used in the video: www.keenlab.de/index.php/port... www.keenlab.de/index.php/prod... " The link is: www.keenlab.de/index.php/portfolio-item/kweld/
I would say diy is still a winner. With those eBay packs.. they for sure don’t use too quality cells like you did for your diy. Nice build.. diy all the way!
If you build your own you also have the ability to fix it when it breaks saving more cash and like you said you’re setup to build more or play with them I made a 36v now taking it apart and it’s gonna be 48v once bms arrives.
thats simple. If you connect them in parallel you'll be able to draw a higher current (rated current of the cell)x(number of cells) and the voltage will be the same as a single cell (so 3.0-4.2 volts), and if you connect them in series you'll get a higher voltage (voltage of one cell)x(number of cells). Since his device only works at over 40 volts you'll have to connect at least 10 in series to get a suitable voltage. If you wanted to build a spotwelder with them(like the K-weld he showed) for example, you'd connect them in parallel instead. You can also combine that like he did. so that means you have groups of 2 cells in parallel, which gives you double the maximum current, and then put those groups in series, which gives you a higher voltage. Thats the electronics basics. Like, first lesson basics.
I would do the series connections first because they handle a lot of current. The parallel connections handle very little current except at the ends and can be done with 18AWG or smaller. Also look up Rinoa Super-Genius because she has assembled several bicycle battery packs.
This please! I actually really want to make my own BMS so I can do regenerative breaking and have different voltage outputs for different things. (lights, traction motor controller, etc.)
@@greatscottlab Can you show how to do BMS for lead acid batteries? I know most people just slightly overcharge the highest cells so that lower cells can get a charge, but that damages sealed batteries like gel cells.
By far the best explanation and video work Ive ever seen on E bike battery creation and function coupled to an unbiased conclusion of price, very business like, very professional, thank you.
I like the video. Just in case you didn't know, I thought I would make you aware of some separate options for cheaper batteries. A popular option in the hobbyist community is to buy lots new laptop batteries and disassemble them for cells. The cheapest option I'm aware of is going for used cells from dead laptop batteries. Used cells are a bit tricky as they must undergoe some tests to verify their capacity and condition. Afterwards you organize them Into a pack with similar cell capacitys. This is the option I went with for my personal battery, I ended up with a 14s 12p battery, it runs about 27ah. It cost me less than 100$, but a fair bit of time. I'm excited to see how your project turns out!
I advise soldering onto the nickel strips before you spot weld them onto the batteries, that way your batteries are not drawing any of the 330°C to 350°C from the soldering iron which can damage the chemistry of your unprotected cells.
Yes you can, most are just a pack of 4 to 8 18650, I take "dead" (usually the managing circuit fails or a cell over discharges) laptop batteries and use them for diy power banks or other proyects.
Since some of the cell may have different parameters after being in "dead" battery, you should check their capacity and ESR first. You can of course use them to create something like a powerbank, but If you would use other types from more batteries, it would be very bad. Also you would need 30, or 60 the same cells with same parameters to create something like this battery. You can not just solder any cell to each other.
Of course, but when you can haul them almost by the literal ton out of tech repair shops you are bound to pile a nice amount of batteries with the same parameters. At least 7 out of 10 will be ready to use, 1 will need some restoring and the other 2 will be dead
Hi, I am a highschool student and for a fun project I decided to build an electric pit bike, as well as building a custom battery to fit the spacing required. I custom built a 52v 28.8ah (14s12p) battery with samsung cells and before I put the bms (50a 14s Daly BMS) on, I tested the pack with a voltmeter and it read around 58.6 volts, which was perfect. However, when I soldered the bms wires on, and put on the connector, it read 14.5 volts. That was around a month ago, and now when I test it the voltmeter reads around 9.5 volts. I checked all of the bms wires and they were fine, so I don’t understand how I am getting that voltage. I saw online that sometimes a BMS can be “asleep” and that you can wake it up by charging, so I tried that and it didn’t even charge. I am now feeling very frustrated and defeated, because everything went so well until the BMS part. Everything in terms of the nickel strips and batteries is good, but it is just something with the BMS. I wasn’t able to get a very good solder on the main positive wire, so that could be the issue. This is all for an electric pit bike project that I’m doing, and I just feel very defeated now, which is why I’m seeking external help. Sorry for the very long email, but this is just the problem that I am facing. Do you know a possible fix or any way I can contact you for you to provide further help. Thanks in advance.
German / Swedish word his pronunciation is therefore accurate nickel (n.) "whitish metal element, 1755, the name was coined in 1754 by Swedish mineralogist Axel von Cronstedt (1722-1765) from shortening of Swedish kopparnickel "copper-colored ore" (from which it was first obtained), a half-translation of German Kupfernickel, literally "copper demon," from Kupfer (see copper) + Nickel "demon, goblin, rascal" (a pet form of masc. proper name Nikolaus (compare English Old Nick "the devil;" see Nicholas). According to OED, the ore was so called by miners because it looked like copper but yielded none."
Other thing to have in mind it's the cell itself, you bought a good one but the pre made pack do the same? In my opinion DIY for the win, and now you can make more packs for the bike or another projects
I've made a couple of multipurpose battery packs and working on one for my bike now. This answered the questions I asked before. I bought a 36 Volt 11Ah for less than $300 also. My motors are 36v or 48v. I had a 36v only that stopped working. Haven't gotten around to see why with others operating and available. I want to increase the Ah and voltage without burning out the motor.
you should have a look at the high capacity rc batteries on hobbyking, you get alot more bang for your buck there, ebike specific batteries are ridiculously expensive
Eduardo Avila unless you're talking about ebike/car batteries then no, not really. It's very possible but lead acid batteries are very heavy for the amount of charge they contain and they don't like full charge discharge cycles. A typical car battery wouldn't last more than 40 full discharge cycles, yes leisure batteries are better but still nothing in comparison to lithium
One thing I would very much like to know, after having built both DIY power banks, power walls and e-bike packs from completely free and recycled cells, which have a higher need for a good and reliable BMS, is how do you discern the good quality BMS:es from the bad ones and how would you go about sourcing affordable quality BMS:es? I've used recommended BMS ciruits from EBay that have been tested, but are still Chinese mass produced things with a varying quality. One does not want to take risks with Li-ion cells or batteries, they can easily turn into great balls of fire which are very difficult to put out and can take your whole house down with you! Where does one find good quality BMS:es in the mid range, that are more reliable and perform better than the average Chinese junk and are still fuctional, reliable and more reasonably priced than the Batriums?
I am working on a very similar battery pack design for my electric bike that I have made. But I have to say, you will want a battery pack more then 5ah. At the moment i am using 4, 12v-18ah lead acid batteries in series to power it, and those get the job done, but I am collecting 18650 cells, and from the research I've done, I wouldn't go under 12ah at least.
Be careful with those chiese lab bench power supply's, sometimes the voltages becomes wrong after use--Then your circuit suddenly fries and you don't know why. When you check power supply voltage, the display says 4.2v and its actually 6v. It's pretty cool.
Good video. I am currently running a 24v 250w setup on my bike. It's powered by two 20ah 12v SLA batteries. Only cost $80. I plan on upgrading to lithium ion when prices get lower.
I would disagree on the DIY=BUY statement here. When you buy components - you have control of what \how are you assembly your battery. When you buy ready product from 3rd party you can end up with bad quality battery(elements/bms etc) & waste of time & money.
I am enjoying this project. I assume it would be preferable to solder the BMS leads to the appropriate nickel strips before spot welding them to the battery, in order to avoid heating the batteries.
amazing video. i was just drawing up plans to do this myself and only afterwards did i find this incredible video. in my case i did a comparison of the diy battery bank to the retail value for my ebike and it saves me nearly $750USD. jeez louisee
Samuel Sparks also, the way to use these is not continuously at full power. You use it as a pedal assist. The current draw is much less and you get hours of use, while still dramatically reducing the difficulty of pedaling.
@Curl Beers That depends mainly on the speed controller, some carry regenerative braking, though regenerative coasting isn't something they normally do.
Sir, why don't you make a video on " how to design schematics and custom PCB using easyEDA ". I know you've already made a video on easyEDA but it doesn't help at all in working on it. I'm really not able to understand which tool is why and which tool is where and tool I need ... What its name..?? Please it will be really helpful. Thank you.. Respect🙏 and appreciation👏 from India🇮🇳🇮🇳.
I bought 14*6-cell lithium-ion laptop battery with some Samsung 2200mah 18650 cells, created a 13p6s 48v 13.2ah battery pack for my bike with some left, its worth mentioning that I used solder instead of welding and used hot glue instead of those spacers....but anyways my bike runs great, fast, for a long time. The best thing is that it cost me only 60% compared to a similar ready-made battery pack, plus a lot of fun.....
Boah Alter! This is BS You bought a 3d printer when I got my first 3d printer, I thought it's all a coincidence. Then I start panning an e-bike. I start planning my battery pack and sketching up the pack on CAD. And then you stat making it too! Stop it! Hahaha All jokes aside, love the video and the coincidence. Might as well show you what I did to get around the task. I build a sport welder from a scrap PSU transformer haha And 3d printer. My battery pack
Why did you did the parallel connection before the series ? Most of the current will flow trough the series connection , while only a small current goes through the parallel connection (just enough current to keep both cells at equal voltage )
I don't think it's the case. Suppose one of the cells shorts, then the other (in the pair) will provide all the current to that one regardless if there is a load or not. May be you meant a fuse between each pair¿?. If it is like that well...that was my point...
Would love a video showing how to make a battery pack with bms.... Charge system AND a mains power system when battery is charging. SO for something like a bluetooth boombox that can still operate under mains voltage while the battery pack inside is charging etc
great video, for reference it is MUCH cheaper to do this even with these batteries for packs bigger than this. I am building a 6x8 battery pack and equivalent batteries are at least 600 dollars more.
Hi great Scott! This was a great video, you are a genius! There is one thing I really want to point out to you for your own good. I have made many ebikes, I purchased a hub motor for the front just like you. When I put it on my bike the hub motor the second I put power to it on the ground the mounting taps broke on the forks. I don’t know what it is but the magnesium alloy is very brittle to the motors torque. I really hope you see this because I have broken 3 forks like that and had to get steel ones. I think it’s a huge safety hazard and don’t want it to happen to you!!!
Most good quality battery packs are 10 to 14Ah so your 5Ah one wouldn't last long. Also $250 to $300 for a battery pack is very cheap. A 36V Bosch battery pack (which uses Samsung cells) of 500Wh (13.88Ah) costs around £700 ($887.94) in the UK. Also using a lithium battery pack/charger without BMS is a quick way to burn down your house!
Yeh becareful on what BMS to Cheap ones am crap ...get wireless one to ur fone so can monitor battery and BMS Some BMS only balance when batteries fully charged and at 20ma cud take forever
@@slicktmi Battery Management System. It's basically a circuit that regulates current and voltage between the cells of a battery during use, and when charging. Most individual cells don't have these, so you have to get one for your battery pack, if you make a DIY one. That said there are some cells that do have a simple BMS included, but they usually aren't appropriate for making into E-bike battery packs.
It would be better to go with 14s2p instead of 13s2p. The extra 2 will give you better cell life as you wouldn't need to charge to 4.2V, but 4.1V instead. That will drastically increase the life expectancy of the cells by 100's, if not 1000's, of cycles. 13s @ 4.2 / 3.7 / 3.0 = 54.6 / 48.1 / 39.0V 14s @ 4.1 / 3.7 / 3.0 = 57.4 / 51.8 / 42.0V This will give you much better performance of your motor as well.
Pretty sure the BMS he was using is not capable of charging the cells part way due to the way it balances batteries. So it wouldn't help. Plus 13s BMS systems are more common than 14s ones. Of course using a difference method of charging where you could charge to a specific voltage would extend the life of the whole pack.
Was wondering, if you had a BMS with and separate charge and discharge negative contacts could you not just join them both together? Would save having a separate connector.
THE best “how to set up” battery pack video out there! I spent years clarifying and watching other ppl do it! You won’t BELIEVE how many ppl don’t tell you the orientations the batteries or the voltage. They just say “oh spot weld or soldier”
Thank you GreatScott
What's the answer for the battery orientation?
That feeling you get when you made something, and it works is "priceless".
i simply aded a switch cables battery clamps and a fuse with a converter .. i even learned that the one side of the converter has different stats when work.. melted some fuses . ruined some solders ... was epic ..
.. when i was 8 . 26years ago my grandpa used to let me play with pcbs and even solder ,, burns and fumes didnt stop me!!!! hope my motivation returns !
I think it's actually priceless, because the feeling is completely separate from the cost. Which is not what quotations adds to the sentence... for anyone that needs to hear that.
@@nicewhenearnedrudemostlyel489 You are correct, I have no Idea why I added quotations. 😅
I began refurbishing ebike batteries a while ago and figured it can be quite a profitable business. That welder you got, appears quite nice and works a lot better than many readymade ones that are available for cheap.
The other benefit of building over buying is that you know you're getting genuine cells. As long as you buy from a reputable place anyway.
Yea however you have to calculate that he also has to protect those cells in enclosure, to protect it from rain, rust, from shorting and whatnot.. :/
@@samihyppia8472 paa÷
!
9999g ki logzgy5 hg
I will never buy a cheaper pre made e bike battery they are all horrible I don’t care what anyone says. Ride a eBay bought bike battery daily from 100-20% charge and it will be completely shot in months! After that mistake I bought all the tools and started making my own, 13s 8.8 ah battery cost $350 including the tools spot welder soldering gun etc but I’m using very good high drain cells. Most store bought batteries can’t handle a lot of current either, my pack can handle 90 amps continuous discharge and 20 amp charge rate. Not to mention you can use 21700 cells and get better watt hour to size/cost ratio. In the long run it’s beneficial because you have the tools and ability to make any battery whenever you need to fit any device. Have a lot of lifepo4 ups upgrades in the future.
At least with a DIY pack build you know that you have good quality cells. Not some cheap un-named brand with no capacity.
Can make sure you buy a pack that names the cells it uses?
and made out of bad Chineseium materials
at that point why don't you just use a gas engine to drive the wheel? lol
I've got a lead-acid battery.
Genset trailers are a thing. I was thinking about getting a little hobby gasser and an alternator, myself.
DIY is always the winner, learning and gaining experience, anyone can buy
I just use 2 multistar 6s 16000mah lipo packs in series. 12s rather than your 13, but that works fine with my bafang 750w midrive. It gives 35mph top speed, and in general use (at effort level 4 and me cycling) I get 35 miles range with that 16ah. Also extremely light - as both packs (giving me 12s 16ah) weight only 4kg. And the 2 packs cost me 120 pounds total. I already had a 10amp 6s charger for lipos. There's no protection from overdischarging of course, but the bike cuts off itself when too low. And the charger balances the cells. I've been using the same pack now for nearly 2 years, and have done around 1000 miles on them and they are still at full capacity.
Your camera work is stellar. I wish more people on YT were this good.
are you in love?
I guess I'll just buy.. It gets complicated after 00:01
Agreed lmao. Started off simple enough.
😂
@@lobsterbaby5302 🤣
nooo lol. watch some more vids. quite easy, really
There's better videos that make it easier to understand. But currently a diy battery is almost just as expensive to make as it is to buy
I really admires that passionate way to explain and recreate experiments like this one.
Keep going in that way mate!
Very nice as always. Do you have plans for an aluminum case for the battery pack?
Not an aluminum case, but something else. Will be in the next part.
I imagine he'll 3d print something.
GreatScott! May be a 3D printed battery case.
I would suggest a flame retardant filament if you 3d print something though, just in case. some of the other filaments are flamable.
Electronoobs i always watch you videos
Big benefit to DIY is knowing your pack is solid. Buying cheap modules can have poor results. Definitely a good idea to crack open what you bought if you can to see how good of a job they did inside.
I think the pro with making your own pack would be making it a larger capacity to the normal ones you buy off shelf. This pack is pretty small as it is. Good start though. Also picking up second hand cells is a good way of cutting costs, although adds risk of unreliability.
I steal the batterys from e scooters, i am rebuilding three batteries into one for my ebike. Yes this is stupid, yes it will work.
@@kevinhorstmann1435 No problem using used cells as long as you check them properly :) I bought a 8 channel tester/charger that tells me exact capacity of each cell
Great video. I wish it had been out a bit earlier because I made my own replacement battery Pack a few weeks ago. I also ordered the cells at accuteile. I soldered the nickel tape to the cells which is a pain in the ... .
Theres one thing you might want to know: I realized the range at which the BMS turned off because of overdischarge was quite low. So I tried to get my head around it and realized that it might be due to short negative voltage peaks at the start of high power consumption (i.e accelerating). So I soldered a 1000uF support capacitor parallel to the output of the batterypack (i.e. the BMS). Et Voila: Range nearly doubled.
I also created a range extender from the old cells which were ok according to capacity but just developed a higher inner resistance. I still try to figure out a good way to parallel the two packs safely. What I do right now is charge them both and then just connect them via a 10A fuse (which by the way blew twice already).
Keep up the great work. I like the accent. I have the same (-;
I believe you should not connect in parallel two packs that are not the same (not same age in your case). When I want to balance batteries in parallel I connect them through a resistor initially, after a while I put smaller value resistor, you repeat that until you cannot see voltage across the resistor anymore which means no current so they are balanced.
Very nice!
Finally a FIY or BUY video that really makes sense - most of the other ones only show what was the best alternative for you (the same doesn't apply to everyone - it depends on your knowledge and budget).
As a Old Ebike rat i was ready to pounce, but this was very well done. Just as a tip typical city traffic load is about 3Amps. max draw usually around 20-25 amp when full throttling from a stop. To extend battery life and range dramatically slowly accelerate Especially in city traffic there is often little need for going maximum velocity. I personally prefer Lead acids on my main workhorse though. I have a Li Ion as a backup. Never use below 12Ah you wont get far.
How would you compare this kind of pack to one based on RC lithium-polymer battery packs? I'm going to be working on an electric scooter project soon, and I was aiming for li-po batteries primarily because of their cost and relative ease of use.
lithium-polymer will be almost the same as far as the math goes compared to lithium ion. If you used packs you would probably want to use 3x 11.1v packs and 1x 14.8v pack in series to get to 13s.
Lipo isn't widely spread despite it's large current advantage in evs cause it has less charging cycles of longevity and is more volatile. Both li-ion and lifepo4 can supply enough current at any reasonable capacity, and lifepo4 has much larger range of operating temperatures.
Do not use lipo is a bomb waiting to set your house on fire. save a few bucks loose your house gg. Use lifepo4 only.
LFP is the safest chemistry but needs a larger volume. Lithium polymer has the best energy capacity so is fine for small gadgets. It is too sensitive for heavy duty power especially with vibration in a bike or scooter. Not safe. Don’t go there.
@@ahah1785 you're fake news!
I like how you make the ads interesting. I have no idea about PCB design but I like hearing random little facts. Clever.
You will find 1kw enjoyable for a brief moment. Then you want more. You will probably build an 5-10kw bike and enjoy it for a moment too. Then you will move into the heavier stuff and beat all the 450cc on the street while realising that you have spent 100x more money on the EV wave than the original budget. But in the end of the day it will all be worth it!
true AF!
We need solid state batteries Tesla gonna start using if they not already
We get the shit overstock or crap batches
they pay bulk prices and get all good stuff shit bags 😂😂
lol. scale that down to 350watt entry level motors and believe me, more than 48v 1500W is scary fast on a bike
Just use a gas bike...
@@mtuz8356 thats not really flying tho...
The difference between DIY or BOUGHT battery packs is that by buying a ready made pack the cells are most likely the cheapest cells with the lowest amount of mAh & discharge rates, the BMS is one of the cheapest & light duty BMS's you could buy.
If you are using a 13s Battery @ 54.6v @ 10amps 546w or 20amps 1092w or 30amps 1638w or 40amps 2184w electric motor then you will be draining such a high current from the battery pack that without knowing specifications of the battery pack it may not provide the power you really need. Plus most importantly lets say you only have a 1500w motor that requires 30amps continuous, if your battery can only supply 30amps maximum then your battery pack will overheat very quickly. To get around this you would need a battery pack that offers more amps maximum so that you are not putting much strain on the batteries.
This is why most people who buy DIY rear wheels with much higher watts than standard will design their own DIY battery packs & specialty BMS with more features & greater control.
this is great, i never understood how to use a BMS until i saw this, i'm using the same one as you
He explained it so well and in only a few words.
Great communicator.
By far the best diy battery pack video on TH-cam
This is by far the best concise video on DIY battery packs. Well done.
Is it on purpose @7:17, it's not complete yet cuz in regards to the right diagram which is in the sketch he showed @4:00 is supposed to be 3 of that 26 battery package he just created and so if I'll clarify you need 78 batteries in order to get a "48v 20ah 1000 watt battery pack"😉
@@johnson12379where did he say he wants 20Ah? He just need 20A, 5Ah.
this could not have come at a more perfect time. The same concepts here for a batter pack could be taken to more than just an e bike and i have been looking for a good explanation that really broke the process down for using li-ion cells.
You can't trust the cells you get on ebay but, labour cost is a major disadvantage (unless you class it as a hobby then its worthwhile)
One point on the BMS, what's the balancing current? it's probably not very high.. so I'm wondering if there was a more severe voltage difference in the cells would the little passive balancing circuit cope with the charging current?
Skruffles Balancing current for most BMS is typically under 50mA
Yeah that's what I thought, even at 100mA I'd be a bit wary of some cells overcharging when series charging the pack.. I suppose some manual checks every now and then would suffice
Germany batteries
DIY is the winner really. Simply because you know it has real Samsung cells inside and you know put a good quality BMS in there.
I think the most important is the connection to the rest of the controllers of the bike. Most of the time, the BMS of the battery needs to talk to the controller unit of the bike. Then p.ex. the display of the bike can show the state of charge (SOC).
I have a ebike in pas 1 I get 2amps in pas 5 still 2amps Do you think the sensor as a problem or the converter has a problem
To be fair, if you used the same cells that those battery packs have, it would probably turn out much cheaper. You can't know what cells those have, could be some cheap Chinese ones.
Which means that the pre-made battery pack would be much more expensive in the long run.
Buy cheap cells from trustworthy sellers on ebay - $1 pr cell at its cheapest
Have you actually done measurements on what is their real mAh? Do you know how long/how many cycles it will last? No. With a good brand one you can pretty much know it won't give out after 10 cycles. Chinese stuff has way less quality control and even same batch batteries can have varying capacity or life.
Newjorciks tru but just like the chinese knife market, it has gone into a new world... Much better than before.. Tbh its safe to buy almost any 18650's.. just not the 9800mAh cells lll
All of it is from China. There is quality Chinese made products. And cheaply made products. simple as that I dislike when people say "cheap eBay crap" or "cheap Chinese stuff" What did you expect for little $
Great video! Make it easy for beginners to understand.thanks for sharing!
You want to match battery pairs by their internal resistance, not their out-of-the-box charge voltage.
TheVexCortex i didn’t know this, I also have never tried to measure a batteries resistance.
Do you just measure it like a normal resistor?
You need a special meter to measure it, if you hook it up to a multimeter, you will probably kill your multimeter. Mine is built in to my charger: www.amazon.com/Version-Digital-Battery-Discharger-Temperature/dp/B00ZGZZ40K/ref=sr_1_32?ie=UTF8&qid=1526094888&sr=8-32&keywords=lithium+charger
www.walmart.com/ip/Tenergy-5-in-1-Intelligent-Cell-Meter-Capacity-Checker-Battery-Balancer-Battery-Discharger-Internal-Resistance-Tester-ESC-Servo-PPM-Tester/179864013?wmlspartner=wlpa&selectedSellerId=2240&adid=22222222227056692896&wl0=&wl1=g&wl2=c&wl3=233956535514&wl4=pla-384625138979&wl5=9022129&wl6=&wl7=&wl8=&wl9=pla&wl10=113146105&wl11=online&wl12=179864013&wl13=&veh=sem should do the job though.
Measure voltage drop in a resistor and do the math.
I admire your honesty regarding the cost.
Great scott, Hi
Thank you so much, with the help of your videos i can deeply understand power electronics
In my opinion ,
Without skilled hands education is useless
Without kind heart education is dangerous
Thanking almighty that you have both
After watching your videos i feel that my skills are improving.
Thank you again :) :)
Thx for al the videos ! I followed this build and now I can cruise on my fast bike in the Netherland!
I really appreciate your effort in these videos.
Just one thing and this’ll be complete!, I’d really like to see a HOMEMADE MOTOR!
Thanks!
It is on my to do list
@greatscott please post a link to the spot welder you got too, i get inspired by your videos and i am the the progress of making my own electric bike kit!
Edit: i meant the one they sent you, not the diy one.
He has posted it in the description:
" The spot welder that I used in the video: www.keenlab.de/index.php/port... www.keenlab.de/index.php/prod... "
The link is: www.keenlab.de/index.php/portfolio-item/kweld/
Satwik Satpathy When i got here it was NOT there, thank you.
th-cam.com/video/NFvMC3l3fGY/w-d-xo.html
For the similar price, but knowing that quality cells have been used, I think build should be the winner of this one. Great video again.
I make a 24v 15ah battery pack.The best 18650
(....) mah and how many batteries are needed? Please say if any kind of BMS will take place
I would say diy is still a winner. With those eBay packs.. they for sure don’t use too quality cells like you did for your diy. Nice build.. diy all the way!
Would getting 21700 batteries be more beneficial?
Tigoo yes
FYI that controller will be using a resistor pair to set the LVM cut off its really simple to change the LVM by swapping out the resistors.
Why you stopped posting links to aliexpress?
Was not worth it
GreatScott! Wait why, because aliexpress products are unreliable?
no, likely because spending the time to hunt the product down on multiple websites is time consuming
real mvp
iwantitpaintedblack looks like someone else can do it for you ^. ^
If you build your own you also have the ability to fix it when it breaks saving more cash and like you said you’re setup to build more or play with them I made a 36v now taking it apart and it’s gonna be 48v once bms arrives.
What is the advantage of connecting the battery holders in series as opposed to parallel? How does this affect current and voltage?
thats simple. If you connect them in parallel you'll be able to draw a higher current (rated current of the cell)x(number of cells) and the voltage will be the same as a single cell (so 3.0-4.2 volts), and if you connect them in series you'll get a higher voltage (voltage of one cell)x(number of cells).
Since his device only works at over 40 volts you'll have to connect at least 10 in series to get a suitable voltage.
If you wanted to build a spotwelder with them(like the K-weld he showed) for example, you'd connect them in parallel instead.
You can also combine that like he did. so that means you have groups of 2 cells in parallel, which gives you double the maximum current, and then put those groups in series, which gives you a higher voltage.
Thats the electronics basics. Like, first lesson basics.
I did not know that the configuration of the battery spacers was so important!
The spacers? i thought you were talking about the nickel strips lol.
I guess the spacers are connected in both parallel and series.
What is the difference? How do those spacers affect voltage and current?
Are you sure....
I would do the series connections first because they handle a lot of current. The parallel connections handle very little current except at the ends and can be done with 18AWG or smaller. Also look up Rinoa Super-Genius because she has assembled several bicycle battery packs.
DIY BMS or BUY? 😁
I have it on my to do list but that will take a while.
This please! I actually really want to make my own BMS so I can do regenerative breaking and have different voltage outputs for different things. (lights, traction motor controller, etc.)
@@WarrenGarabrandt me too
@@greatscottlab Can you show how to do BMS for lead acid batteries? I know most people just slightly overcharge the highest cells so that lower cells can get a charge, but that damages sealed batteries like gel cells.
buy
All hail the greatscott by far the best electronics youtuber with the most soothing voice I ever heard. Can you please read me bed time stories
6:55 I guess those conections were serious
By far the best explanation and video work Ive ever seen on E bike battery creation and function coupled to an unbiased conclusion of price, very business like, very professional, thank you.
I like the video. Just in case you didn't know, I thought I would make you aware of some separate options for cheaper batteries.
A popular option in the hobbyist community is to buy lots new laptop batteries and disassemble them for cells. The cheapest option I'm aware of is going for used cells from dead laptop batteries.
Used cells are a bit tricky as they must undergoe some tests to verify their capacity and condition. Afterwards you organize them Into a pack with similar cell capacitys.
This is the option I went with for my personal battery, I ended up with a 14s 12p battery, it runs about 27ah. It cost me less than 100$, but a fair bit of time.
I'm excited to see how your project turns out!
I advise soldering onto the nickel strips before you spot weld them onto the batteries, that way your batteries are not drawing any of the 330°C to 350°C from the soldering iron which can damage the chemistry of your unprotected cells.
DIY is a clear winner if you allready have the 18650 cells
Do you have 30 (or 60 in bigger packs) batteries just lying around? I have some from old laptop batteries, but I can't use them together of course..
Yes you can, most are just a pack of 4 to 8 18650, I take "dead" (usually the managing circuit fails or a cell over discharges) laptop batteries and use them for diy power banks or other proyects.
Since some of the cell may have different parameters after being in "dead" battery, you should check their capacity and ESR first. You can of course use them to create something like a powerbank, but If you would use other types from more batteries, it would be very bad. Also you would need 30, or 60 the same cells with same parameters to create something like this battery. You can not just solder any cell to each other.
Adam Grufík if they are diffrent parameters then you use bms or try to manage get same capacity bunch for one group of cells
Of course, but when you can haul them almost by the literal ton out of tech repair shops you are bound to pile a nice amount of batteries with the same parameters. At least 7 out of 10 will be ready to use, 1 will need some restoring and the other 2 will be dead
Hi, I am a highschool student and for a fun project I decided to build an electric pit bike, as well as building a custom battery to fit the spacing required. I custom built a 52v 28.8ah (14s12p) battery with samsung cells and before I put the bms (50a 14s Daly BMS) on, I tested the pack with a voltmeter and it read around 58.6 volts, which was perfect. However, when I soldered the bms wires on, and put on the connector, it read 14.5 volts. That was around a month ago, and now when I test it the voltmeter reads around 9.5 volts. I checked all of the bms wires and they were fine, so I don’t understand how I am getting that voltage. I saw online that sometimes a BMS can be “asleep” and that you can wake it up by charging, so I tried that and it didn’t even charge. I am now feeling very frustrated and defeated, because everything went so well until the BMS part. Everything in terms of the nickel strips and batteries is good, but it is just something with the BMS. I wasn’t able to get a very good solder on the main positive wire, so that could be the issue. This is all for an electric pit bike project that I’m doing, and I just feel very defeated now, which is why I’m seeking external help. Sorry for the very long email, but this is just the problem that I am facing. Do you know a possible fix or any way I can contact you for you to provide further help. Thanks in advance.
5:37 Did he just call the ribbon the N-word? :O
5:40
NO! He said, "Nickel ribbon"
I really like diy version cause its not only fun to make but also we can know exactly whats going on and always we can repair it ourselves.
5:40 "The n***a ribbon"
He's fucked up the pronounciation so many times, it's hilarious.
German / Swedish word
his pronunciation is therefore accurate
nickel (n.)
"whitish metal element, 1755, the name was coined in 1754 by Swedish mineralogist Axel von Cronstedt (1722-1765) from shortening of Swedish kopparnickel "copper-colored ore" (from which it was first obtained), a half-translation of German Kupfernickel, literally "copper demon," from Kupfer (see copper) + Nickel "demon, goblin, rascal" (a pet form of masc. proper name Nikolaus (compare English Old Nick "the devil;" see Nicholas). According to OED, the ore was so called by miners because it looked like copper but yielded none."
cANcELleD
Other thing to have in mind it's the cell itself, you bought a good one but the pre made pack do the same?
In my opinion DIY for the win, and now you can make more packs for the bike or another projects
I'd of doubled that pack it wouldn't last long on a 500w hub
I've made a couple of multipurpose battery packs and working on one for my bike now.
This answered the questions I asked before.
I bought a 36 Volt 11Ah for less than $300 also.
My motors are 36v or 48v. I had a 36v only that stopped working. Haven't gotten around to see why with others operating and available.
I want to increase the Ah and voltage without burning out the motor.
you should have a look at the high capacity rc batteries on hobbyking, you get alot more bang for your buck there, ebike specific batteries are ridiculously expensive
Depends what you're going for. Hobbyking Multistar cells weigh 40% more for the same capacity compared to 35E's, and many new 18650's do cost less.
Well, currently on Hobbyking: 10s 10A lipo pack (20C discharge, 2C charge) - 40 EUr, incl. shippment to Europe. I think it is a quite good deal.
Tibor Kiss Hey, could you put a link to that battery, I can't find :(
Or you know bike/car batteries could be used too, with some circuitry together
Eduardo Avila unless you're talking about ebike/car batteries then no, not really. It's very possible but lead acid batteries are very heavy for the amount of charge they contain and they don't like full charge discharge cycles. A typical car battery wouldn't last more than 40 full discharge cycles, yes leisure batteries are better but still nothing in comparison to lithium
One thing I would very much like to know, after having built both DIY power banks, power walls and e-bike packs from completely free and recycled cells, which have a higher need for a good and reliable BMS, is how do you discern the good quality BMS:es from the bad ones and how would you go about sourcing affordable quality BMS:es? I've used recommended BMS ciruits from EBay that have been tested, but are still Chinese mass produced things with a varying quality. One does not want to take risks with Li-ion cells or batteries, they can easily turn into great balls of fire which are very difficult to put out and can take your whole house down with you!
Where does one find good quality BMS:es in the mid range, that are more reliable and perform better than the average Chinese junk and are still fuctional, reliable and more reasonably priced than the Batriums?
Isn't LFP better
Safer but lower energy density
I am working on a very similar battery pack design for my electric bike that I have made. But I have to say, you will want a battery pack more then 5ah. At the moment i am using 4, 12v-18ah lead acid batteries in series to power it, and those get the job done, but I am collecting 18650 cells, and from the research I've done, I wouldn't go under 12ah at least.
Be careful with those chiese lab bench power supply's, sometimes the voltages becomes wrong after use--Then your circuit suddenly fries and you don't know why. When you check power supply voltage, the display says 4.2v and its actually 6v. It's pretty cool.
Am I the only one impressed by this guy's clean handwriting style?
5:40 so sounds wrong...
ni**a ribbon
Glad someone else heard it too lmao
Good video. I am currently running a 24v 250w setup on my bike. It's powered by two 20ah 12v SLA batteries. Only cost $80. I plan on upgrading to lithium ion when prices get lower.
10:05 holy shit look at that spark!🤷🏻♂️🤣😁😎
PCB for only $2 is deceiving. shipping is minimum $10
The "serious" connections are very important. BTW, make sure to not spot weld in the center of the battery contract, stay to the outside a bit
add a 3d printed enclosure for the kweld
I just xant believe that he is just 1.1 mil subs he deserves more
I would disagree on the DIY=BUY statement here. When you buy components - you have control of what \how are you assembly your battery. When you buy ready product from 3rd party you can end up with bad quality battery(elements/bms etc) & waste of time & money.
I am enjoying this project. I assume it would be preferable to solder the BMS leads to the appropriate nickel strips before spot welding them to the battery, in order to avoid heating the batteries.
5:41
the *what*
amazing video. i was just drawing up plans to do this myself and only afterwards did i find this incredible video. in my case i did a comparison of the diy battery bank to the retail value for my ebike and it saves me nearly $750USD. jeez louisee
But with only 5Ah and drawing 10Amps you will only have 30 minutes of charge...
True. But that is why I will do testing in part 3.
Samuel Sparks also, the way to use these is not continuously at full power. You use it as a pedal assist. The current draw is much less and you get hours of use, while still dramatically reducing the difficulty of pedaling.
Can it charge when coasting? Like some Hybrid cars do?
30 minutes of full power, usually you don't drive around like that.
@Curl Beers
That depends mainly on the speed controller, some carry regenerative braking, though regenerative coasting isn't something they normally do.
I like how you give as school lessons thx and God bless you my brother 🙏
Awesome video, very, very instructive! Thanks a lot!
No problem ;-)
Gotta tell you that today i made an 80$ order + some LCSC smd things, thank you for the continuous quality reviews! gotta check it out for myself!
Sir, why don't you make a video on " how to design schematics and custom PCB using easyEDA ".
I know you've already made a video on easyEDA but it doesn't help at all in working on it.
I'm really not able to understand which tool is why and which tool is where and tool I need ... What its name..??
Please it will be really helpful.
Thank you..
Respect🙏 and appreciation👏 from India🇮🇳🇮🇳.
I will make such a video when the time is right.
GreatScott! Will be waiting eagerly..😊
I bought 14*6-cell lithium-ion laptop battery with some Samsung 2200mah 18650 cells, created a 13p6s 48v 13.2ah battery pack for my bike with some left, its worth mentioning that I used solder instead of welding and used hot glue instead of those spacers....but anyways my bike runs great, fast, for a long time. The best thing is that it cost me only 60% compared to a similar ready-made battery pack, plus a lot of fun.....
Boah Alter! This is BS
You bought a 3d printer when I got my first 3d printer, I thought it's all a coincidence.
Then I start panning an e-bike.
I start planning my battery pack and sketching up the pack on CAD.
And then you stat making it too!
Stop it! Hahaha
All jokes aside, love the video and the coincidence.
Might as well show you what I did to get around the task.
I build a sport welder from a scrap PSU transformer haha
And 3d printer. My battery pack
Why did you did the parallel connection before the series ? Most of the current will flow trough the series connection , while only a small current goes through the parallel connection (just enough current to keep both cells at equal voltage )
so diy if you feel like it?
Yes
Most of the battery packs you get within a reasonable price is recycled or non brand cells. So I think DIY is a win anyway.
0:12 I have that screwdriver
Is there any safety measure in case one cell of a pair shorts? Thanks!
Add a fuse or connect a thermistor in series with the load.
I don't think it's the case. Suppose one of the cells shorts, then the other (in the pair) will provide all the current to that one regardless if there is a load or not. May be you meant a fuse between each pair¿?. If it is like that well...that was my point...
5:32 "nigga ribbon" :P
even "worse" at 5:40 lol
Lmao had me dying
I was sure I wasn't the only one who heard it 😂😂
Sounded like nickel to me, I guess you just heard what you wanted to hear.
LOL!
Would love a video showing how to make a battery pack with bms.... Charge system AND a mains power system when battery is charging. SO for something like a bluetooth boombox that can still operate under mains voltage while the battery pack inside is charging etc
why didn't u show the bike on the road
Part 3?
Because it’s just a battery pack and wheel right now. It obviously isn’t put into a full bike yet
GreatScott!
yes
Have you ever thought about creating a mild hybrid system for daily drivers?
I have bought 200 li-lon battery for 5 dollars XD in a garage sell
Hamza Ezio Argh... for $20 Can I have 35 cells ? x)
Time to start going to garage sales.
3:02 I always respect people that are able to use fineliner pens, without smudging it around.
I really needed this video. Making a lipo battery pack for a project but was confused about the BMS.
great video, for reference it is MUCH cheaper to do this even with these batteries for packs bigger than this. I am building a 6x8 battery pack and equivalent batteries are at least 600 dollars more.
Hi great Scott! This was a great video, you are a genius! There is one thing I really want to point out to you for your own good. I have made many ebikes, I purchased a hub motor for the front just like you. When I put it on my bike the hub motor the second I put power to it on the ground the mounting taps broke on the forks. I don’t know what it is but the magnesium alloy is very brittle to the motors torque. I really hope you see this because I have broken 3 forks like that and had to get steel ones. I think it’s a huge safety hazard and don’t want it to happen to you!!!
Most good quality battery packs are 10 to 14Ah so your 5Ah one wouldn't last long. Also $250 to $300 for a battery pack is very cheap. A 36V Bosch battery pack (which uses Samsung cells) of 500Wh (13.88Ah) costs around £700 ($887.94) in the UK.
Also using a lithium battery pack/charger without BMS is a quick way to burn down your house!
Put it this way ya only use half the stated capacity cause can't fully drain batteries to 0 volts so he built 2500mah 😂😂😂
Yeh becareful on what BMS to
Cheap ones am crap ...get wireless one to ur fone so can monitor battery and BMS
Some BMS only balance when batteries fully charged and at 20ma cud take forever
@@davey2k12 what's bms
@@slicktmi Battery Management System. It's basically a circuit that regulates current and voltage between the cells of a battery during use, and when charging. Most individual cells don't have these, so you have to get one for your battery pack, if you make a DIY one. That said there are some cells that do have a simple BMS included, but they usually aren't appropriate for making into E-bike battery packs.
Is the welding necessary? Couldn’t you just solder them together? (Newbie question I know)
It would be better to go with 14s2p instead of 13s2p. The extra 2 will give you better cell life as you wouldn't need to charge to 4.2V, but 4.1V instead. That will drastically increase the life expectancy of the cells by 100's, if not 1000's, of cycles.
13s @ 4.2 / 3.7 / 3.0 = 54.6 / 48.1 / 39.0V
14s @ 4.1 / 3.7 / 3.0 = 57.4 / 51.8 / 42.0V
This will give you much better performance of your motor as well.
Pretty sure the BMS he was using is not capable of charging the cells part way due to the way it balances batteries. So it wouldn't help. Plus 13s BMS systems are more common than 14s ones. Of course using a difference method of charging where you could charge to a specific voltage would extend the life of the whole pack.
Was wondering, if you had a BMS with and separate charge and discharge negative contacts could you not just join them both together? Would save having a separate connector.