Parallel connecting Lifepo4 batteries of different brands and sizes! Extreme Parallel Part 1!
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- เผยแพร่เมื่อ 6 ก.พ. 2023
- I've wanted to do something like this for a while now. I have a few different 12v Lifepo4 batteries and I hate the fact that I'm not using them as they are intended! I've decided to see if I can connect them in parallel and be able to use them as a backup source of power for cloudy days!
I also wanted the batteries to all have their own fuse so I decided to use a 100A fuse block instead of a bus bar.
-=Items in this video:=-
UNOWIX LiFePO4 Deep Cycle Lithium Battery
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Official UNOWIX website:
unowix.com/unowix-defender-x1...
Ampere Time 12V 50Ah Lithium LiFePO4 Battery, Ideal Replacement for 12V 100Ah AGM SLA Battery
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Li Time Official Website: www.litime.com/?ref=f-naaMXh7...
SFK-275HP 12V 275AH HIGH POWER LITHIUM IRON PHOSPHATE BATTERY
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Use coupon Code "OGB" at checkout and get the Heated Battery Bag for Free! This is only for the 275ah battery. Also, Free Shipping on this Prebuilt Battery!
12-Way Fuse Block, Waterproof Boat Fuse Panel 12-24V Marine Fuse Block with LED Warning Indicator Damp-Proof Cover - 12 Circuits with Negative Bus Fuse 12V Box for Vehicle Car Boat Auto
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BNTECHGO 12 Gauge Silicone Wire 10 ft red and 10 ft Black Flexible 12 AWG Stranded Copper Wire
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#12vbattery #parallelconnection #lifepo4
Yes, it works quite well and won't hurt the batteries. Since they are paralleled, the voltages will even-out once the current tails off. The SOCs will not even out (more on that later), but the voltages will. You do have to take a few precautions however:
* First, you have to limit charge and discharge current to what the worst battery in the bunch can handle (which will typically be the battery with the lowest number of amp-hours). The reason being that it is possible, even likely, that situations will arise where most of the BMSs will disconnect on low-voltage or on high-voltage and potentially leave just one battery active. If it happens to be the worst battery of the bunch, it must still be able to handle whatever you throw at it.
* And second, you have to be cognizant of the paralleling limit, which is a short-circuit feed-in limit basically. It is typically 4 batteries of the same Ah rating... which means that poor 50Ah battery is way over the limit (150Ah of other batteries).
The solution to the paralleling limit is to simply add proper fusing. You kinda did that, though not in the usual way and for different reasons. But that is the solution. LiFepO4 batteries of the same voltage (same # of cells in series internally) can be paralleled more or less infinitely as long as proper fusing is done to protect the wiring and for battery safety (the paralleling limit in manufacturer specs).
--
Also note that the SOCs for LiFePO4 batteries connected in parallel will never balance out on their own due to the flatness of the discharge curve. But once you've cycled the whole mess a few times, the SOCs WILL be in lock-step, albeit offset from each other by up to around +/- 10% (due to differences in the internal resistance of the cells). And because of that, the current sharing will NOT be absolutely bang-on. But it will work as expected on average.
So as long as you do not count on 100% perfect current sharing, it works surprisingly well.
Thank you for the great information!
you should always connect batteries with positive terminal first, then negative
I was never sure. Thank you for the information and the comment.
Your thinking outside the box, way to go.. !! many of us have the same scenario with different amp hour 12 volts.. looking forwards to part 2
Thanks! I'm just trying to get the most out of what I have. Thanks for the comment!
That was very interesting. The batteries seemed to even out without any of them getting too high. Can't wait to see what happens next.
I find it all quite amazing! Thanks for the comment!
Interesting test with the different batteries and including the 50ah battery. I will be back for part 2.
It will be coming out tomorrow! Thanks for the comment.
This video is amazing, so clear and concise! Ive learnt so much, thank you!
I'm glad you found it helpful! Thanks for the comment.
Great video. Id love to see more videos like this
Thank you for doing something I always wanted to
You are so welcome! Thanks for the comment.
The experiments you are doing are cool.
Thanks! I'm just trying new things out with the equipment I have. I don't like having these batteries just sitting around, not getting used. Thanks for the comment!
Putting a lot of time and effort into this video, great job 👍
This is just the start. It seriously gets SUPER time consuming with testing and editing the videos coming up next! :-)
@@OffGridBasement See your videos are better than mine 😋
This is how I am running my heating pad for my battery box. It runs off a 400 watt inverter with 3 different 12v in parallel with a 100 watt panel. And a cheap pwm charge controller. I am using a seedling mat that only draws 33 watts when on. Keeps my 9 lithium iron phosphate toasty warm. But I am using 2 agm and 1 deep cycle battery works great so far
That is quite the mixture of batteries! It's really good to see you making the most of what you have available. No batteries should go to waste! Thanks for the comment.
This is FUN. 👍
It is, isn't it?!
This is the practical test I can understand!!
Solar-People telling me I need 2/0 cable to connect my 2-100Ah LIFEPO batteries(same size), in parallel. When I'm using them in my cargo-conversion trailer, and maximum draw will be 30A, for lights and a small inverter. I'm not running large appliances, etc. And the maximum charge will probably be 60A (from an AC charger), and that would be if the batteries are dead.
I can do wire size math, NP. And NP upsizing a bit. But 2/0 seems like overkill to me. IMO
All that to say, this test is going to be very telling, thanks for doing it!
I believe that is overkill. If they're 100ah batteries, the most you will pull is 200amps or 2560w. That is where they are getting the 2/0 cable from. I think it can handle 250 amps. Personally I would use 2 awg cable and a 150 Amp fuse at the most. 6 awg cable to handle 75 amps. You could use that and a 100 fuse between the battery bank and the inverter / bus bar. If you are going to use smaller cable, make sure to use a fuse. Good luck!
@@OffGridBasement I always fuse/breaker.
I use a main fuse, then breakers to branch circuit, then car fuses to each small circuit. Basically, I breaker or fuse at every wire size changes.
Thanks for the videos, I understand electric and DC above average. Been soldering and messing with electricity and circuits for over 50 year. However, the delicateness (for lack of a better word) of Lithium with Solar is a new genre for me.
Thanks again!
8/0 is all you need for that if your runs are short. Look up a wire gauge chart to be sure. Don’t listen to idiots…including me. Easy to look up what you need. 2/0 is so expensive.
Cool experiment.
Thank you.
Cool test
Thanks!
Thanks for sharing! I know it's pretty cool to see how the different size batteries all tend to balance out together.
Before I started documenting my solar setup, my original 12v system consisted of 2 different batteries, one was 280Ah, the other was 200Ah (and actually the 200Ah was in a 2P configuration of separate 100Ah packs). I played around a little bit watching how the 2 different packs charged and discharged.
Now I'm working on converting my old 12v system into a portable power station. To start it'll only be the 280Ah battery, but I wana make it expandable so I can add the 200Ah battery down the road.
That is a great use of old, unused batteries. They're going to last for years so you might as well get some use out of the extra capacity!
great test, best regards
Thank you very much!
thank you sir, that was educational...
Glad it was helpful! Thanks for the comment.
Thank you
You're welcome. Thanks for the comment.
I was told by LiTime battery not to use mismatched batteries and to use the same batteries manufactured within a 90 day period.
So this video will be interesting, thanks!
It is definitely recommended to build a bank with all the same batteries. That way you have the same resistance and BMS settings. This just proves it can be done, not that it's the best way to set up your bank. Thanks for the comment and info!
@@OffGridBasement But I love and appreciate your videos! Keep them coming sir!
What is the yellow multi-meter with the clamp-on current testing feature you're using in this video? It appears to be quite accurate. Thanks.
It's a clamp on Multimeter from IDEAL. I bought it at my local Lowes. Thanks for the comment.
Cool, in my lead acid setup with many different amp hours on each battery i find in parellel you get the lowest voltage of the bunch, so im guessing charging those 3 should only get them to 13.48, the lowest charge thats sticks on one battery. So you loose some voltage headroom but make up for it with capacity. I got situation where one of my batteries only "sticks" at 12.4, the others go upto 13.2 so it drags the rest down, but i get double the capcity so makes up for it. The ideal soltuion is to turn on the 12.4 battery when the others get down to 12.4, so it really doesnt drag them down. So maybe a dynamic switching system, turning the batteries on as they get close to their ideal voltage coupled with charging them seperatley so they can reach their max voltage. This would get the most out of a parrell system with miss matched voltages, but simply adding capacity in a parralel situation can more then make up for any voltage loss. Anyway, looking forward to the results because im also curiouse to where the amps go when they're parallel charging.
I believe you are correct about getting the voltage of the lowest battery. Thanks for all the good info!
Curious now…..I have battery bank size issues with mine. I’m afraid I have boxed myself into a corner with my battery bank. I have 4 100 li time batteries in parallel. I need more capacity. So really interested in how this turns out. Any ideas for adding more than 4 in parallel?
I know the documentation states that it maxes out at 4 in parallel. What about if you have 2 sets of 4 in parallel? They are technically all still in parallel, but they would be on completely different wiring all the way to the bus bar. Just a thought. Thanks for the comment and question!
Do AGM batteries need to be equalized? I have have heard both yes and no. So I dont know
I thought that was only for flooded batteries, but i can't be positive. Thanks for the comment.
Hi .This experiment is valid if you use different type of batteries like Lead acid and Lifepo4? Thanks
I personally don't recommend combining batteries of different chemistry. Thanks for the comment.
can i ask. i have two different set of batteries 12v.
12v 16ah gel type
12v 25ah lead acid
but one output is it okay to use them directly im not gonna parallel them but connect them in one output
You really shouldn't connect two different chemistries together. Know that, the most important thing is to get the voltage of each battery to be as close as possible to each other before connecting in series. Matching at the highest charge level possible. Hope this helps.
@@OffGridBasement how about connect then in parallel?
I think these batteries can go as high as 14.5 volts, so they still had some space to be filled. So one having more pressure than other might push it's excess into another. Sotheby's way I understood, basically voltage is like the depth of water ,capacity is the amount of water. You can have ocean of water, but a pipe sticking 20 feet down will have the same pressure as the water reservoir having 20 feet pipe submerged under water. And if we drain water through these pipes it will take couple days to drain water reservoir, but thousands of years to drain ocean. Or if the level of the sea is 10 feet ,but a pool of water 100 feet it will have 10 times more pressure, even though it's only the size of a pool.
I believe that is a great analogy! Thank you for the info and the comment.
I have two 100Ah batteries. However, one is 12V and the other is 12.8V. Is this is a problem if I want to wire them in parallel?
I figure as long as they are the same chemistry you should be fine. Do you know what the max charge voltage of the 12v battery is? it might be 13.2 while the other is 13.8. Just keep that in mind.
I have 16 eg4 48v 100ah batteries, but i need more storage. I want to buy a 1740ah Industrial flooded lead acid battery. ( forklift battery) is it possible to use these together? These are for a off grid solar system
I don't recommend that. The charging profiles are different and I believe the internal resistance is different as well.
Can you show me where on the fuse board the cables go as it confuses me as they run in parallel so could you number them like 123 etc on the fuse board please
It really doesn't matter where you put them on the fuse block since they are all running in parallel. Just make sure to wire all positives to the positive section of the fuse block and all the negatives to the negative section.
@@OffGridBasement thank you I couldn't get my head around it as to all running parallel thank you once again did you know you can charge them up with a ev power point
What about connecting that 350ah bank of that parallel,to another of that kind and make it in series to make a 24v system?
Wow. You're talking about REALLY mixing things up. I'm not sure. As long as each 12v bank in the series totals the same AmpHour capacity, then it should be ok. I would need to test that to make sure. Thanks for the comment and the idea!
I had a jump box to start cars. When the lead battery went bad I replaced it with 4 lithium batteries from other jump boxes that quit working but the battery was good. The batteries were smaller than what you have but the wires was much bigger at 0 gauge. I used the trickle charger to keep it charged. Worked great for years until a friend jumped a car backwards and the battery pack caught fire.
Oh man! Glad to see something like this worked for years. Thanks for the comment and info.
😮
I was told hooking up different amprae batteries together can be done but you have to make sure you start off with all the battery voltages are the same. I have two sized Valence batteries and the manufacture warns against using two different size batteries hooked together. Maybe because the BMS will shut down if it noticed the batteries are way out of balance?
I don't think the BMS would care about them being out of balance. One thing I know it cares about is the amount of amps being pushed or pull to/from the battery. If the voltages are way off then the amount of amps being transferred between the batteries could be too much for the bms.
I really think companies are just trying to keep you buying their batteries. There is something to be said about all of the batteries in the bank having the same BMS. That is something you should really keep in mind. You don't want one battery shutting off @ 11v and another shutting off @ 10.5v.
@@OffGridBasement " You don't want one battery shutting off @ 11v and another shutting off @ 10.5v." this is exactly my point
Do you have a video of the 3 difference ah battery connected and complete system and running, i'd like to see and learn from it? i have the same idea about the battery and i found your video it so helpful thank you keep doing it with your brain storm.
Unfortunately I don't have a complete system with this setup. This was a demonstration. Thanks for the comment.
Unfortunately you found out that different chargers due to programming, electrical components and what not will consider a "full" battery something different.. Even two identical chargers from the same company will have fully charged them differently.
Batteries of the same chemistry and different capacity can be used together safe-ish as long as you consider a few things.. Ideally I would keep my max current usage to the capability of the smallest battery in the group. LifePo4 batteries like you have should all have a BMS so that kind of eliminates that problem.. If everything goes wrong, the BMS should protect the battery.. And since you have the fuses rated for the wiring, then that eliminates the problem of overheating your wires.. So go for it! :)
Thanks for the info!
I'm surprised that the current was only 3A with such high voltage difference. I'm about to connect my two batteries and sitting here wondering whether them being within 0.01V is close enough :)
Ha! I think you would be just fine! Thanks for the comment.
Would have been good to see if there was in rush current when first connection was made
Thanks for the comment. The in rush current would depend on the SoC of each battery.
I would bet any negative effects would be less when using a 24 volt system. Wire gauge, connection tightness and conducter quality is very important for non resistive connections @ 12 volts. The wires you are using are too long and too small in gauge for a high cap 12v system IMO. Everything would be OK @ 24v. Most solar MPPT charge controllers support 24v and one can buy cheep 24 v inverters and 12v down converters. The advantage is much more affordable ( smaller gauge ) wires. This philosophy saved me a lot of money as I hooked my solar panels in 100v ( series) arrays so I could run just 10 Guage conductors to them. Seriously, anyone hooking up a battery bank ( that doesn't go in parallel with a 12 volt car battery) NEEDs to absolutely go 24 volt ! It's more expensive to go 36v or 48v.....
Yes. The wires are small because the fuse block can only handle 100amps. I went into this knowing it would only be used for small loads.
Connecting different ah batteries in series is not efficient. If you connect a 50ah and a 100ah battery in series you are only getting a 24v 50ah battery bank. You would only get the capacity of the lowest ah battery.
I want to see the charging stuff too
That video will be coming out tomorrow! Thanks for the comment.
@17:17 FREE ENERGY MACHINE! Or not lol...
Haha! I wish! Thanks for the comment.
12 gauge wire is enough if the system will not run a high load like 500 watts appliances
I have a 240ah and 60ah lifepo4 pack and i want it to connect in parallel
Maybe it is safe to parallel connect a different size of lifepo4 battery pack with individual bms
I believe there is no problem. There will be some balancing issues when you get to the top or bottom of the SoC of the bank.
@ 12:18... lol... live wires,, just, swingin' in the wind (hanging off the workbench)
Hahaha! Dumb... I don't recommend doing that! Thanks for the keen eye and the comment!
@@OffGridBasement i was nervous.
Do lead acid and lithium to make 48v
Myself, I wouldn't be mixing different brand batteries together, not sure if it would cause
a negative effect to the batteries. But, I'm no expert.
My reason for the concern is I wanted to build a large Series/Parallel LiFePO4 battery bank,
but Redodo recommends you purchase all your batteries from them, within 3 months of each other to be in the same battery bank, 6 months for Chinns Batteries.
So, maybe it's something to do with changes they make to the batteries over time.
It's alot of money to shell out in such a short time to get that big battery bank of 16
batteries I was hoping for.
So, in 3 months I was able to get four 200Ah Lossigy batteries for my system.
Maybe, someone could shed some light on this issue why I shouldn't build
a larger battery bank over 12-18 months.
I believe the reason they say that is so the resistance is the same across all the batteries and that the BMS have all the same settings. If it's your main setup I wouldn't mix and match batteries. I think you can get away with waiting just don't connect old batteries in series with new ones. Series connect batteries of the same age and parallel connect them together.
@@OffGridBasement OK, good info about the BMS. Just got a reply back a reply from Lossigy,
They recommend up to 6 months. "12 months is a little long, and the capacity of batteries will vary". I guess it's got to do
with the aging process of a battery and keeping them close to the same manufacturing date. Something to keep in mind, Thanks.
You wont be able to draw 20amps a channel on that auto fused distrabution board it will get very hot- the spring contacts just wont handle it
I don't plan on drawing that much per channel. 10a per channel is the most I was planning. Thanks for the info.
DC power exits the battery at the negative and not the positive..
Thank you for the info and comment.
I'm thinking it should stay roughly the same.....or revert to roughly the pre-balance state of charge!!!!
As I'm watching 7 months later, I'll find out in a few minutes :)
give myself an uppercut
Thanks for the comment.
Cheap fuses will arc if there is a short you will have s mess! It’s not about how many amps you Wanna draw! It’s how much potential energy the system contains, fuses protect wire not devices right .
That is true. if the inverter I connect to it ever has an issue and shorts out, there might be a lot more issues then a burned up inverter. Thanks for the info.
Hello,
Nice video.
I have a technical question, I'm sure you know the right answer, I don't.
You have 3 different batteries and 3 different BMS's.
In parallel you add the Amp's together.
50 + 100 + 275 = 425 Ah.
I don't know the different BMS capacity you have in the batteries.
Can you add the Amp's of the BMS's together too?
BMS 1 + 2 + 3 = X
Regards.
Willy
😊
Yes, correct. If you have a 50, 100 and 100 amp BMS then you add them together for full input/output. This example would be 250 max continuous draw.
@@OffGridBasement
Thank you very much for your service. Willy.
When you introduced the inverter, you lost me....
Are you trying to speed load, you know that is counter productive right? Don't get me wrong, I've did my experimentation as well, but I didn't make a video about it.
The inverter was just to show the amount of amp draw you can do from this type of setup. The fuse block is only rated @ 100amps so you don't have to use a very big inverter.
I'm not sure what you mean by speed load. I'm just showing that you can use different size batteries at the same time in parallel.
if this I all you need? Why do the so called " experts " preach USE a battery balancer??? I dont have this answer. I just got started with LFP4 two 12v 100ah and now they shot the price up on the brand I have so I want to get a different brand, Where is part 2 of this???
If your batteries are wired in parallel you don't need a battery balancer. The balancer would be for individual cells wired in series. Batteries or cells in series don't keep the same voltage.
Here is a link to part 2: th-cam.com/video/e_UkBStWkhY/w-d-xo.html
very bad idea to use different batterys with different amps together ....
Can you explain why it's a bad idea? The reason I'm doing these tests to find that out.
More detail would sure be helpful here. The way I see it, with same chemistry and BMS on each, the output/USE of the batteries is not likely to be problematic. The charging (from a charger or solar controller) might be - on the charging side, we have to realize that the chargers are smarter than they used to be - they make decisions on bulk charging versus float and trickle based on the OVERALL voltage they see at their leads. This winds up being an average in your case and may make the charger do a less than optimal job. Is it harmful? I'm not sure. But I think (I'm NOT the expert here and am seeking the truth as well) that you don't get what you truly want, optimally. But if you wind up in a safe situation that gets you 90% of optimal, then GREAT. I'll have some similar needs in the coming year for mixed LiFePO4 batteries and am quite interested in your findings. And I'd love to hear from @stefan why it's a bad idea.
@@bobwolff68 I'm going to experimenting with this idea for a couple more videos. I just don't like this idea of not using the storage capacity. I'm going to incur big losses in conversation, but I'm interested in what those will be.
@@OffGridBasement I'd be happy to keep in touch on the topic and drive it to a conclusion with ya.