What's in the little red box on some jump-start leads? (Guess first.)
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- เผยแพร่เมื่อ 29 ก.ย. 2024
- With the increasing popularity of the mini lithium jump starters for cars, there seem to be some standard components appearing. One of them is this set of plug-in leads with that mysterious little box on one of them. So here's what's inside.
I've not taken a look at a jump starters yet as I don't have a load high enough to test them to their often dubious specifications.
Note that there were two types of package in the unit, one with a rating of 40V and one 45V.
Jerry Korner has done some tests though, so here's a link to one of his test videos. • Video
It appears that there has been a recall on some of these leads due to the exact scenario I described of overcranking and causing the diodes to fail short circuit, followed by rapid failure of the lithium pack. www.cyntur.com/...
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
www.bigclive.co...
Many years ago I tried to get into the local nightclub on a saturday night, but the guy on the door wouldn't let me in because I wasn't wearing a tie. So I went back to my car and wrapped my jumper leads around my neck, and tried my luck again. The guy on the door said "o.k, you can come in, but don't start anything"
Boooo
Ok that's actually funny.
thanks for sharing. :)
was it dead inside?
Hehe
Pint of electrolyte please.
Maybe the diode pack is there to protect the lithium battery pack from the alternator's output voltage once the engine starts?
Yeah that makes sense it was that simple
Yeah I thought the same thing to be fair 👍
Geeze thanks for spoiling it!
But the alternator charge controler limits the output voltage 🤔
If the clamps are used incorrectly, connections reversed, the jumper will not work.
That's a fairly typical drop for a big schottky at low currents, it doesn't stay that low under load though.
I'd guess it might go quite high at the real life starting currents. Oh, remember your little pyrophoric incident? I've just had one that I also caught on video.
I have one of these kits. Mine is rated for max current of 400A. And it will only let you try to start for 3-5 seconds before it times out, so you can't just hold the key on and continue to draw. And it really has been enough to start my work F-150 on multiple occasions.
Even before lithium jump packs there were some supposedly "EFI Safe" jumper leads had a similar box on them, supposedly because ordinary jumper leads would fry the electrical systems of EFI cars, but everyone just uses ordinary leads on EFI cars & nobody has fried one.
Wouldn't be long until those cars stopped working thanks to Y2K though. I hope they had their Y2K-compliant jumper cables ready.
I know extremely little about electronics. My guess was immediately (as in, before clicking on to the video): "I bet it's a bridge rectifier". It seems anything that isn't a capacitor or a microchip is almost surely a bridge rectifier...
Sometimes I watch your videos just to hear you say "So let's take a look inside.. oh interesting.. so here's the bridge rectifier...."
I should make a drinking game out of it.
Diodes are there to protect the safety circuitry and cells of the rechargeable pack from pulsations in the 14 to 17v range from cheap voltage regulators and alternation generation. Automotive systems can swing VERY wide of 12v since they're technically 14v systems.
I have the Tacklife lithium jump pack, but I paid like $80 for it. So decent money. NEVER used it for myself. BUT weirdly get asked a lot to jump other people's cars. Hasn't failed me yet and the handful of times I've done it, the battery BARELY goes down as well, while working perfectly each time. SO... the circuitry seems pretty alright.
Could it also be a safety feature so if you connect the leads backwards they won't just go pop and melt?
thx for the vid, and yeah for ridicalus 2.5GBP it doesnt look like an bad deal, hence 10awg silicone wires and clamps, and partically not if you can use it as a emergency jump starter for us there got a bunch of high C rated lipo packs for RC..(assume 3cells is obvius hence 12v, but how will the car-cirquit and battery handle fx 4/5/6s and the higher voltage if one only had lipo cells higher then 3cell, or are there an limiter there will protect fragile cirquitparts from higher voltage in most cars.
anyway thx for the notice, I also took the plunge on one of these shipped for 2.58GBP, intersting video +1.
Solder, what could possibly go wrong in a very high current application?
Would love to see someone pass 2 kA through those leads. YT sez Jerry's video is unavailable.
The boss of who's manufacturing these should be told to hold these while his "1000A" clamps are at the test. He should show us how it's done and i'd like to see his frying face when he's holding them
I'm so disappointed that the spudger worked. I wanted to see you wielding the hammer of knowledge!
Yay I guessed right! I was told once that car jumper leads should have diodes to protect modern car computer circuits
Guessing first that its a fuse, or a bimetallic switch, that'll open if its too warm from overheating.
What's in the BOX!!!??? any SE7EN fans? lol
my guess - magnet? to reduce noise?
you mean like a ferrite choke, eh? Not magnets but ferrimagnetics.
ye exactly , im not electrician but u know what i meant.
the forward voltage is low because you have many diodes in parallel. Forward voltage changes as you add more diodes. I'm not sure if it is supposed to go down or up offhand, though what you saw would suggest that it drops.
Justin DiPlacido Yeah, the usual ~0.6V divided by the 4 diodes= ~0.15V.
Andrew Delashaw It's not resistors, the current / voltage relationship is not at all linear.
John Francis Doe
your right John. Its still going to be around 0.6 Volts.
no it will not, the diodes will share the current, and the forward voltage of the combination will then be lower as each diode operating at a much lower current. he's just saying you can't divide the .6V by 4 diodes to get .1V
Justin DiPlacido
Hi Justin. As the diodes are in parallel they will have the same voltage across them. I cant see how they are conducting if the voltage is less than 0.6 volts, can you explain please. Thanks
Like the new channel logo Clive.
im guessing its a diode.. to keeps voltagefromgoingback to pack.
possibly for reverse polarity protection
What they ^^^ said 👍
@@Noughtta But when connecting the charger with the polarity wrong, it's in series with the battery, so the diode would be forward biased, anyways.
is that a joke? 🤦♂️
Zener action?
My guess is: “I watch this channel because it’s relaxing but I don’t actually know how electricity works”
Secret: Neither do the professionals. Tesla did though.
@@Songwriter376 In what way did he "understand" electricity? I keep hearing this about Tesla but all I get is some confusing conspiracy replies. I'd be grateful if you could explain it.
@@ScooterZn There are many sources on youtube about him. If you are a reader I suggest the book TESLA, MAN OUT OF TIME as it gives one of the best bios about him. Engineers still do not understand magnetism or how it works but they do know how to use it to generate power. Likewise, they do not understand what electricity is but know how to use it. Tesla, who is the father of most things we use today like electric light, motors etc etc, could understand somehow just exactly how to make an electric motor by understanding the properties of electromagnetic eminations from coils of wire arranged in such a way as to make the motor turn. All wothout notes or drawings. Did it in his mind!!!
There are others out there like Stubblefield, Moray etc who made great research and discoveries with explanations as to how a magnetic field really works and how it actually manifests into our dimension but some of those books are tough reads.
Don’t pay attention to any crazy theories out there but read a book about his life and discoveries. Many still poo pooh him because he challenged the accepted authorities of his time on how things work. Hope you do investigate and read about this very under rated and genius of a man man who’s discoveries and many inventions shaped the modern world into what it is today. Zoid.
Most electricians are bluffers
Something to do with marbles in a tube and angry pixies in the wall, don’t think you need to know much more than that to be a sparky! Oh, and don’t let the smoke out!
Not only does this protect the li-po (or li-ion) in the power bank against reverse polarity, this also has a significant use in "standard operation". As soon as you fire up your car's engine, the alternator kicks in, delivering around 14V towards battery terminals. Both the alternator and the power bank might not like it (I would expect a significant current going into the li-po), that's why they are so consistent on reminding you in the manual to disconnect the device as soon as the engine starts.
90msg90 Reverse polarity clamping will pass right through those diodes, as the leftover voltage in the car will act like a hugely flat battery drawing a lot of amps until something fails, probably violently. I'll be like shorting a 24V extra beefy battery.
Still, the argument remains valid. Those jump start packs re usually 3S packs, which means they have a maximum voltage of 12.6V when fully charged. High amperage 30-40A at around 14-15V that a car alternator is happy to churn out will make your pack go thermonuclear in a matter of seconds. Diodes prevent that.
90msg90
That happened to me a few years ago, bought a cheap jump start thing on ebay, decided to try it out and intentionally drained my battery
Well i hooked it up, turned it on and started the car, worked very well, but my 100A alternator disinigrated the jump starter before i could even exit the car, i guess there was no diodes in that thing lol
If one wanted to design a LiPo jump start pack with safety foremost in mind, rather than cost, it would be a simple matter to add a voltage sensitive relay to the package, which would detect when the voltage on the car got higher than the voltage in the pack (i.e. when the alternator kicked in). That said, these things are churned out of factories by the tens of thousands in China, and a VSR would add substantial cost to a production run.
Use your power supply and put a load of 5A over the diode-module. Then measure the voltage-drop, this will give you a more useful measurement.
In case anyone was let down by jumper cables they sell at gas stations and supermarkets (those that have far more insulation than actual copper), here is a recipe for cheap yet indestructible jumper cables:
- buy 4 welder ground clamps. Those are very robust and are usually rated for 300A+
- buy 4 lug connectors
- buy 6 meters of 25mm^2 welder ground cable (or thicker). You will make two 3m cables out of this, buy more if you need longer. This type of cable is very soft even in low temperatures.
- split cable in half, crimp or solder lug connectors onto cable, connect to clamps
- congratulations, you have jumper cables that can start a diesel truck.
MasterBata in a pinch you can run smaller wires in parallel with any type of clamp(even hose clamps) to hold the wire on the terminals
@@SLAutoRepair In the days of chrome plated bumpers, two cheap cables in parallel to the positive terminals and the bumpers touching for the ground connection.
My friends managed to jumpstart a car with a couple of the aluminium foil trays you put under barbecues
I have what is basically a bug-out box. Rechargeable, comes with a light, usb inputs, 12v car jack, standard us power socket, air compressor (although a kinda weak one, works for when your tire either just loses pressure over time, or if you've got a small hole) and the thing weighs about 40 pounds, so it's got the oomph at least, unlike these wimpy starter packs.
@@thegeneralissimo470 - I have one of those too. Also includes a work light. What's your point?
Hey Clive, i just wanted to say thank you for making these excellent videos. I've learned a lot i wouldn't have otherwise, and been entertained the whole way. I recently got an electronics kit for my birthday and i'm having s great time experimenting with it, as well as trying some soldering tricks i've learned from you. Thank you
3:40 what a beautiful soldering job
ikr XD
Yeah, that's what I thought!
At this point it's more like welding
could of just poured liquid solder at this point
Pretty good for 6 year old children i thought lol
damn, I always thought it was just one of those massive car fuses.
Not a bad price for the clips alone either.
It is probably worth buying for the clips.
could probably use the diodes for a solar charger, that was a pretty good FV.
totally. my nipples are hard in anticipation just looking at them!
Depending on how soft the jaws are they could be quite useful beyond anything electrical as well. They look a lot more robust than the standard chinese plastic spring clamps that are found all over.
Would make an excellent set of charge leads. Already has what looks like an ec5 on the end, and those clamps are better than the tiny alligator clips that come with a typical hobby battery charger. I use mine to top up my car battery, an imax b6ac. It has a setting for the lead acid battery and outputs only up to 5A, the lead would handle it fine.
BTW, I knew it would contain a diode in that box before the vid started. :) Really, what else would it be?
I'm guessing wire straight through! (That would be hilarious)
EDIT: I was wrong, but hey, Clive suggested it as well :D
As a seller of lithium jump packs, I can tell you so many are crap. there are some good quality units such as the NOCO, but anything that uses this cable are rubbish, the clamps break at the hinges, the cables melt in the connector and at the teeth as all the current travels in through 1 side, also most of the cables are aluminium. the diodes serve 2 purposes, firstly they stop reverse connection, for about 5 seconds until they explode. they also stop the pack from being reversed charged from the alternator, as there are only 3 Li-Po pouches inside the 14v from the alternator is to high. the other problem is after cranking for a few seconds the diodes fail. now all these failures are assuming the li-po pouches dont explode first. most of the packs that use these leads wont start more than a 4 cylinder. or charge a phone. i should do a teardown, i have several different types of packs sitting around.
Good i have a 4cyl
I have a 3 cylinder.
When I was like, 11-12 I had a huge interest in electronics and tech, learning what components did, and all that jazz. I have no idea why my interest petered out, but it did. Now this channel shows up and has kinda resparked my interest a bit, while also being very relaxing and entertaining to watch!
I'm sure that the spark gap between the two diode rails is Electroboom-level testworthy!
*Arcing intensifies*
@@danwic Excelsior!
In this case, the diodes are used to prevent the alternator from shoving tons of current into the lithium battery when the vehicle starts, nothing more. It does NOT provide reverse polarity protection. If you hook the booster pack up backwards, things will get quite exciting quite quickly, guaranteed, unless the jump pack has some sort of protection internally.
I've had bad luck with these lithium jump start packs. For one thing, their performance drops dramatically when cold, which ironically is also when you're most likely to need it.
I much prefer ultracapacitors for jump starting. You get WAY more amps and they are not affected by low temperatures nearly as much.
Yep, these cables can't help with reverse hookups. It will cause the positive terminal to look like -12v to the charger, so it will dump everything it can into the battery attempting to reverse charge it. That would go very very bad. It needs some brains to detect a negative voltage scenario, letting it know the cables are backwards. That's actually easy to implement... but don't expect the feature!
I have two ultracap jump packs, mainly cause I think they're so cool, and also because they don't have a limited lifespan like the lithium packs do. Although ask me again in 10 years to see if the ultracaps are still ultra.
Those jump starters are simply 3S lipos batteries (and b-grade noname ones at that). I made one just using a battery I already had for my quadcopter (4000mah 40C), some heavy gauge wire and some good quality clamps. The only problem with them is that when the car turns over and starts you must I immediately disconnect the LiPo from the car as the voltage from the alternator (>14V sometimes) can damage the LiPo. And that's why they now put diodes in series with them.
For a dummy load, run a number of car headlight bulbs in parallel. You can even switch them in one by one to see what happens (and avoid most of the current spike caused by cold filaments).
Fascinating video, very well explained. If only I knew what the hell it all meant!
It's a start of a rabbit hole he goes deeper and deeper he explains it clearly enough but you still need the understanding of it all
😂
Just finished watching Project Farm videos on the jump starters shootout. Great info from Him without any bs
Well i guessed "a diode"
so im right and wrong all together? :D
I guessed diode! What's the prize?
A balloon full of Magic Smoke.
But was it an np or a pn junction?
2000 Amps DC on 10 AWG stranded wire , copper plated AC/CU plated. 400 Amps would fry it to a crackling crunch. It may hold before bursting into flames but someone would get the shit burned out of them. I'd like to see it at 2000 amps or even 1000. Yes they are relying on it being a short period. New car starters are tiny compared to ones from the 1970s. That said I have a jump starter pack with a lead acid battery, made by a major company that has worked spectacularly for years. FYI made by Schumacher but only claims 650 amps. It starts my tractor, my truck and the wife's Toyota Camry. It has saved us lots of time. hassle and money...The original cost was about 50 dollars. I will be changing the battery in it this year.
Stupid question...The numbers on each of the diodes is different. Does that mean they are differently rated? I dont suspect its just a different manufacturers number as they dont tend to do this...confused mechanical brain here.
The top rows are some datecodes or fab-codes or something; the part numbers are on the bottom row. I see two SBL2040CT and two SBL2045CT - the only difference between those is the reverse voltage rating (40v vs 45v), but that shouldn't affect anything in practice, in this usage scenario.
cant find those diodes on ebay for cheap. is there an alternative diode that could be used ? was thinking in making a board of 5 of these to add to my car charger for reverse polarity protection ?
The changing number quite likely are datecodes when they were produced. With the numbers all over the place it tells you they used "leftovers" and not new stock from a reel (the dates also look like the parts are from 2001/2002).
In a proper design you would never do that, because you must not put diodes in parallel without precautions (this is true for LEDs as well). Diodes from different batches will have slightly different characteristics even if it's the same part number. And mixing different part numbers like they did (2040CT and 2045CT) is a big nono as well. The problem is, if the diode aren't almost exactly the same (not just the type, but in measured electrical characteristics) and thermally coupled to each other (at least they are on the same piece of board, so that's a bonus), there's always one that conducts slightly more current than the others at the same voltage. More current means more heat for that diode and diodes conduct better when they are hotter! So the diode takes even more current, heating up more and more. Depending on how much you overload it, it might die immediately or after repeated use. Now that that diode is dead, it's time for the second best conducting to take it's turn, except now the current will be devided between on less diode, so more current for all of them and die even faster. That's also a good way to kill LEDs if you skimp on limiting the current of each strand of LEDs individually.
+Mix Bag, here's a link to options available from Mouser (Schottky diodes, 20A and above, 40v and above, sorted by price).
www.mouser.co.uk/Semiconductors/Discrete-Semiconductors/Diodes-Rectifiers/Schottky-Diodes-Rectifiers/_/N-ax1mj?Rl=ax1mjZgjdhqdZ1yuoc7iZ1ypakakSGTax1mjZgjdhq5Z1yuoc6sZ1ypakalS1ya6ncwZ1yuo4zqGT&Ns=Pricing%7C0
+Mix Bag Check how the diodes are oriented. These diodes are not reverse polarity protection (no point in having that with power sources on both ends anyway). They are back feed protection.
small thermonuclear fusion reactor
Nah...the box would have to be yellow then.
In that package it is unlikely that they are NOT Schottky diodes.
fuse is too obvious so I am going with half added diode attempt to stop the car charging the battery or reverse polarity protection (but being from China the diode will be grossly under rated. )
MMM. that was actually reasonably decent spec. not bad.
This is a Big Clive video, so I'm just going to shout things like "Bridge Rectifier". Even though a Bridge Rectifier wouldn't be in a cable designed for DC.
Feeding DC into a bridge rectifier is a handy technique to make the device operate normally on AC or DC irrespective of the polarity.
Eg. anything electronic that is connected to a telephone line will use this technique.
FULL BRIDGE RECTIFIER
There's enough diodes for one, tho.
no it would be a capacitive dropper
Irony: ends up being filled with half bridges...
I know this is a old video, but i have one of these that i fried trying to start my car. It is constructed in the same way, but the tin is a low meltpoint metal like rose metal making it effectivly work as a fuse. What happend to mine was that the main lead melted and fell of. The diodes are probably there in case of someone reversing polarity on the terminals.
No magic smoke? I'm disappointed
There will be lots of unexpected smoke and flames in the next video.
Not unexpected anymore :(
Clive did you get a new microphone?
I shall be very upset now if there isn't.
connect the lead across a big battery 800+ cca and then there will be magic smoke
Well you showed what's inside but you failed to say what it does. I had to figure it out by myself (and have it confirmed by other commenters): reverse polarity protection and overcurrent protection once the alternator kicks in. You should have said so yourself in the video. Come on, don't expect us to think for ourselves. We're watching youtube videos, that's one of the laziest things conceivable.
He says half of that right at the end of the video - but yeah it could've been more clear and better explained.
Is it a little elf on a hamster wheel to generate enough energy to jumpstart the batter?
Liam Wiltshire guessing after watching the video isn't fair
Of course not, don't be ridiculous.
It's obviously a gnome in there.
Behave it's like a hamster turning the London eye lmfao
The Tyttuutface if you connect it to a step up transformer connection to a battery
@@the486kgman2 Transformer, more that meets the eye. Transformer, little elf on a hamster wheel...
i believe the block in the wire is a lossless diode made of mosfets to prevent the car from charging the jump starter
Diode for reverse protection in cans you hook them up to a battery backwards. Should have lights also but not always, usually will have a red and green LED to show when they hooked up correctly or reverse polarity.
„What"s in the box miss fox” - love Ya! ;)
3:40 those are schottky barrier rectifiers (SBL2040CT= 250 amps max) SBL2045 = up to 150 amps. both 40-45 peak reverse volts, to protect alternator.
The 'magic' red box seems straightforward to me. You basically have 8 diodes in parallel to handle the large current draw and prevent reverse polarity hookup and voltage back flow from the 13v-14v alternator when the car starts. The low voltage drop is due to there being 8 diodes in parallel where each silicon diode would drop around .7V. I don't see any confusion about this setup.
Also, you mentioned that it could draw 400 amps. I'm sure those (10 ga.?) wires would melt at 400 amps. Put a clamp meter on it to see what it's really drawing when you start the car. I may do my own such test as soon as I get a DC clamp meter.
Yeah, Clive, PLEASE blow up your car in video for us all! Please?
The low gauge wire can support 400 amps for a short period of time like jump starting requires.
I think you have just found the ideal solution to connecting several 12v batteries to a small bank of solar
panels but where each battery can power its own circuit and not another circuit from another battery.
I think i explained that properly? eg. 4x 12v batteries . 100w panel connected to all 4 through these
cables. Then each battery connects to an LED lamp.
Thanks
fuse,,cant,think about something else
dammit.
I saw one with capacitors ...want to buy....but the price ..damn
380 euros
they indeed act as quasi fuses, however the main reason for these diodes is so after the car starts, the car's alternator doesn't cram 40-50A into the liPO pack.
Erik Bruijn and ui
mondayfool Yeahhh ...if I didn't answer so quick I could have known however tose with caps don't have them you can charge them via the leads in seconds
start booster? wouldn't it be easier to service your car battery once every five years?
I've got one of these clips that started to melt that box covering the diodes when starting an old truck with a carburetor, meaning it took awhile, but it never failed! This explains the heat! And we need to see a vid on how much amps these things can take, push it to the max! Love your vids by the way
I guessed correctly, perhaps I am learning something from watching all these electronics videos after all LOL
If you connect your jump starter to a battery that is fully charged and your jump starter didn't get recharged after you used it last then current would flow from the highly charged battery to the depleted one. In the case of a lithium battery that might mean it would get more amps than it could handle without damage.
Another scenario might be where you drain your jump start battery and just as that happens the car starts and throws power back to the jump start battery faster than it could take it.
MHO
You can always count on Big Clive to tackle the big mysteries of life.
Actually, schottky (and normal) diodes increase forward voltage drop with current, so on multimeter it can show 0.1V, but in operation, during jump starting the current be around 400-600A.
That would be 60-85A per diode (there are 8 diodes), and the voltage drop would be above 1.1V (the datasheet shows 1.1V drop at 40A instantaneous current and then the chart ends :P ).
At this range of current - schottky and normal diodes behave quite similarily, there wouldn't be noticeable differences in heat generated by schottky and normal diodes in this application.
For a drop of 1.1V at 85A - each of the 8 diodes would generate 93.5W of heat per diode (750W for all 8 diodes). Possibly much more, because the chart doesn't show forward drop at such high currents. Also, I think the datasheet I saw shows voltage/current chart per package (two diodes) not per diode - that would mean that the heat will be even higher :P.
I would say, that after fairly short usage this plastic little box would melt away, far sooner than any isolation on the cables.
You may consider it a fuse of sorts :P. A kind of fuse that leaves your hands burned if you use the jump starter too much :P.
Reverse Polarity protection incase an idiot like tries using them.
Thats what i thought backyardbasher, diodes are ment for one way. Eden's Aquaponics why is polarity protection impossible?
There's no point of reverse polarity protection when there is power sources on both ends. It is backfeed protection.
Yes this is how most reverse polarity protection is implemented. I think Dave Jones did a video on this.
And what happens when you are jumping a battery and connect it up wrong? You know connecting the the red to negative - and the black to positive +. This is also called reverse polarity, it is also called a dead short. These diodes are a one way check valve type of device for electricity keeps idiots from burning out the electric systems in the car.
Take a look again. The way the diodes are mounted they *conduct* from car the battery when the cable is connected with the wrong polarity. Guess why? Because it's not a reverse polarity protection.
It’s a cigarette lighter, older cables sometimes have that, the ones with the fold out ashtray on the negative side are very rare.
A device to prevent reversing the polarity of the neutron flow!
Input Voltage 24v is work output 24v or not work
I love watching your videos, almost as much as do pretending to understand what in hell you're saying!!
I am pretending i understand that.
try using a salt water load, tub of salt water and one of the electrodes v, (arrow) shaped move up and down to allow adjustment of load,
spodula the Vampire Yes I saw that method used to control the speed of a Big Wheel at a fun fair years ago.
4 schotty diods solderd to a braslike connector.... just guessing
sure....
for anybody wondering, its not for reverse polarity protection, its because the full charge voltage of the pack inside is 12.6v, thats fine for starting the car but once it does start the alternator brings the battery voltage up to 14.4.or even as high as 14.7, if this was reverse fed into the lithium pack it would destroy the cells, likely in an explosive manner.
Guess: Diode.
DING DING DING! booya! I figured it'd be to protect cheap lithium booster packs from polarity issues
It's a miniature flux capacitor. Those Chinese are clever bastards.
There's a hot girl in there :D
can't think about something else :D
I would love to see one of these jump start packs explained. how the hell do they get enough power to jump start a car? I went out to a totally flat petrol engines fiat doblo... no lights on the dash flat as a pancake. customer comes out with one connects it up and boom off she goes couldn't believe it had enough power to start it and didn't even seem to struggle!!!! I bet a normal small car battery would have taken a while to get it going. I usually use leads off my twin battery Toyota Hilux. keep up the great work Clive your videos are superb and make me more interested in electronics every time I watch!! :-)
The secret is in the very high current capability of the lithium cells optimised for sport applications. That's also what makes them quite scary, as they tend to fail violently if damaged or overloaded.
Li-po-ion cells can have crazy high current limits, and since it only needs that current for
It's that "fail violently" part, why I don't use them in automotive applications, even for jump-starting. Bound starters or dead shorts can draw as much current as you can feed them, and I don't feel like putting out another car fire, thanks. ;)
Yeah to be honest I like jump leads because if the discharged battery will take a charge you can give it a charge for a while to lower the massive draw and not melt something. I've used quite a few of the classic style jump packs but they can be hit and miss. that and I'm too tight to buy one...
It makes me laugh when you get people jumping of a 12v battery (not on a vehicle) and wondering why it still won't start. The fully charged battery and 14.5 volts and 100amp from the alternator don't half make a difference
lol and you can leave the leads on to give the alternator chance to start charging. I'm preaching to the choir now. :-)
There is usually so much resistance in the clamp and leads that the load is not as massive as one may think. In addition, by giving it time, you are allowing things to heat up. And then consider that there will be losses in the vehicle battery itself, both charging and discharging. I believe it's best to turn on the jump starter and immediately crank the engine (making sure all possible accessories are turned off first). It can be helpful to have someone tightly squeeze the clamps for better contact.
For some reason I've had a lot of experience jump-starting vehicles. I'm just too nice. The old lead-acid jump starters are such a pain in the ass, with the need to lug them around and recharge monthly. I just love these lithium jump starters. They can go in your pocket and only need charging once or twice a year if not used.
¨What´s in the box?¨
My guess was Gwyneth Paltrow´s head.
A lot of people think the diodes are for reverse voltage protection when putting the cable clamps to the battery backward. The diodes do not offer reverse voltage protection as noted further. If you connect in reverse then first the battery and booster are in series and will be dead shorted across each other the degree depending on the battery state of existing charge. (The high current surge might be enough to cause a diode failure if it failed opened. This would be a quasi fuse protection effect, but not reliable as diodes can fail as shorts as well.) The boost back will try to discharge and recharge the car battery in reverse voltage polarity as the voltage at the boost pack is greater than the car battery. A very harmful effect to lead acid batteries. If it could still crank the engine, then the alternator output voltage if greater than the boost pack would try to reverse charge it. Very bad, but might tolerate a momentary connection. But the alternator would attempt charging the car battery.
In normal operation. The diodes serve simply 2 purposes of isolation: Prevent the car battery and/or alternator from trying to charge the boost pack since the factory likely has there own preferred charging profile and a cc/cv type charger.
So in theory you could delete this feature? I have been through 3 sets of these leads because they keep desoldering themselves when jumping a car. If i deleted and kept the time attached to the car at a minimum it wouldn't actually hurt the box right?
No, in case the LiPo is 3 cells in series it can handle 12,6V max. Once the car starts and the generator is putting out 13-14V, it would destroy the LiPo pack, possibly in a very violent manner.
The diodes prevent this.
In other words it is for reverse polarity protection, but connecting the car battery backwards *isn't* reversing polarity - it's the desired polarity but with an extra current source.
@@nomennudum4592 well two batteries in series increases the voltage, and so normally the amperage can increase as a result, but that's irrelevant here because the two batteries have virtually no load between each other. It's a dead short. Don't think there will be any (usable) voltage left for the vehicle during that situation. You may even present some nice reverse polarity voltage available to the vehicle's system. If that ends up flowing through the system get ready to pop a few components. Don't worry it can only cost hundreds or one thousand dollars to fix.
@@activemanishere I got rid of my diodes and it works great. I keep the time attached to the car minimum.
What's in the box? Gweneth Paltrow's head obviously.
Wouldn't the diodes protect "things" in the event someone inadvertently connects the leads backwards?
dam all that talk about not much.
I bought one of these jump starters recently and, like Clive, the first thing I did was open that little red box to see what was inside.
And I’m extremely glad I bought it! I left my lights on overnight, and was greeted by a flat battery in the morning. The jump starter didn’t work on the first try, so I left it to recharge the car’s battery for 10 minutes and then I was good to go!
4:58 Hey Clive, as you probably have realized by now, the reason for the very low Vf you're measuring is because each diode has a Vf of 0.6V (as you'd expect and as confirmed by the datasheet), however what you're measuring is 8 of them in parallel.
Are...Bart. just think about what you said! They are not resistors so you don't divide the voltage by the number of diodes old chap.
I guessed it! The diode will prevent the Alternator killing the LiPo when the car starts. A care with a 120A alternator would kill the LiPo very quickly with the surge current.
Good info, Clive! Never thought of the issue of higher Alternator voltage (as others are mentioning) needing to be blocked from the jump pack.
I didnt realize i was watching a UK video narrated by Robin Williams lol. Keep up the good work. Yall have a similar voice
Chinese Ebay sellers work on high volume, almost zero profit. Cant figure out postage.
@bigclivedotcom: there seem to be four different (according to the printing on them) kinds of diodes in the red thingy, you only looked at one of them when reading the type around 3:35+... strange.
I'm guessing diodes inside, most likely SBL2040CT. Im quite sure it must be four of those in parallel soldered direct onto two individual brass plates.
Something many people don't know is. If you connect more than one diode in parallel the effective threshold voltage drop will be lowered. Just like resistance is lowered in a parallel circuit.
.. matching diode characteristics in parallel (Voltage forward (drop) or current sharing ) is "better" if the diodes are matched (one technique is to get match diodes where their breakdown voltage is within 50mV @ some I ).... if not the Vf (shared) won't be the lowest.
Decent quality versions of this (complete sets) are quite effective! even a small 800a unit was able to start my small block v8 2002 dodge dakota naked (no battery just the jumper) I was quite impressed. No magic smoke
The good one will only run so long to prevent you burning them up or worse setting off the lithium pack :-) I only buy ones that charge via USB since the other ones inevitable become paper weights when you use the damned dedicated charger cord :-)
ones with usb charger ports are the best. lithium batteries degrade from lack of use. so being able to use it as a usb power bank means you can exercise the battery a little between times you need to use it which keeps them healthy longer.
I can't wait till they release some LIFEPO4 versions. those should have a much much longer lifespan.
Before the "big reveal", my last guess was "NOTHING" :D But as it turns out, i was wrong...
I'm going out on a limb here not having watched the entire video yet.
Reverse protection. You don't want current flowing back from the boosted battery into the lithium pack once the car starts.
That isn't reverse polarity protection, it's reverse current protection which is a very different thing.
Go back and reread what I said.
"You don't want current flowing back into the lithium cells from the alternator once the car starts:
12voltvids: Since you have now edited your post to remove the word "polarity" there's not much point is there? You do realise that it shows as edited right?
mikerjuk
I corrected the word "boosted" as word substitution changed that on my phones and I didn't catch it till I went back to fix it so that is why it shows edited. I didn't change anything else I had the part about reverse polarity protection in there from the get go, to refer to it charging from the boosted battery. nothing to do with connecting it backwards or dead shorting but it would protect against that too as the diode pack would blow open like a fuse so I stand by my observation and original post which wasn't changed other than correct the word "boosted"
These diodes are very common in cheap ATX PC power supplies, they are used on 3.3v and 5v output rails.
I've used 3 different jumpstarters successfully before. They are all brandless and from china. I'm really interested in how they work. Thanks in advance
I've seen a few of these fail, the wires desolder themselves and the plastic box melts. From continued cranking like you thought.
you really dont need a load greater than say 500a. The lithium cells just arent capable of more than that and any company claiming more is full of it.
ferrite coil to prevent noise
I'm guessing a fuse or some sort of protection thingymabob. (written when the ad was playing)
What's in the boooox?!!
I looked at those lithium jumper packs for over a year before I bought one. I read some reviews, crunched the numbers and then took the plunge. I bought a brand called "Bully," more on that later.
I charged mine and threw it into the back of my car. Not a month later my Volvo V70 had a dead battery. Out came the jumper pack. The car has the battery in the back and a terminal under the hood for "jump starts." That terminal has never done me any good even with another car supplying power. So I hooked the Bully to the batter, positive to positive and negative to negative. Turned the key and it started fine.
Recharged the battery and put it back in the car. Checked it a few months later and the battery was swelling. Oh, oh. Called Bully and I had a new one in a few days.
Last week, I had a dead battery again. Bully to the rescue.
So far, I'm a believer. Just buy a brand name at a reputable store.
I was hoping for a bit more explanation of the circuit in the red box and what it does, but basically its just a set of diodes to stop the current flowing back from the battery to the power pack then?
I had assumed it played some part in the ‘boost’ part of the jump pack, so it was capacitors or similar that wouldn’t pass the current until it had built up enough to “jump” the battery. I’ve measured the output of my jump pack and its about 13v, so it really acts no different to any other battery placed in parallel to your car battery.
You paid less for your replacement from ebay than I did Clive, my jump pack stopped working and when I measured it, the red bit had failed open circuit. Bought a replacement set of leads off eBay, and then your warning about them getting hot came true, first time I tried to use it to jump my dead car the red bit got so hot it melted the solder on one of the red leads and it fell off ! Was quite hard to heat the solder enough to re-solder it back on ….