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Lithium batteries not supported in Series

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Diemjoe

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I seem to be running into the same problem over and over. It started with 2 Big Battery 12v 170Ah batteries that I purchased based on their specs they could be run in series for my MppSolar 2424 hybrid. Had everything hooked up and they went put of balance pretty quickly. Discussed it with them and they said they no longer supported 12v in series.
Then I went and got 4 12v Rich batteries with the specs say they can be 4 in series or parallel. They are working as a bank of 2 24v batteries for the past couple of years. Now it's time to increase everything for the Cabin that I am making progress on.
I am looking at the EG4 6000 xp and two 48v rack batteries with the hope that I can include the 4 Rich in Series for another 48v 100Ah battery. The specs say they can go 4 in Series. Their customer support begs to differ though. They say they do not balance when in series. Ugh.
They recommend that I look onto a balancer. Does anyone have any experience and/or recommendations? Any concerns about mixing batteries?

Thanks

Don
 
Doesn't take much looking on this site to discover stringing 12V in series isn't optimal and actively discouraged. When folks must, the recommendation is to get a balancer.

If you're mixing the same nominal voltage, it can be made to work.

You need to take your 12V and individually charge each to 14.4V for two hours. You should observe NO charge protection events. Then you need to parallel them and hold at 14.4V for 2 hours. THEN you can string them in series. Hopefully, they'll be internally balanced.

Lastly, LFP batteries need to attain "balancing" voltage regularly enough to ensure the BMS can keep the cells top balanced.
 
HA02 balancer (4 batteries) works well for me with 2S2P 12V LiFePO4 batteries. You can find them on Amazon, Aliexpress, etc. Specs say up to 10A balance current... but with my clamp meter, I've never seen more than 0.8A. My understanding is that batteries need to be VERY out of balance to get anywhere near even 3A. I fused each positive lead with a 5A fuse and have never blown one.
My understanding with this balancer is there is no requirement for the 4 batteries to be in parallel or series or connected in any way at all. HA01 exists for 2 batteries, there are also HC02 an HC01 with integrated voltmeters.
 
sunshine_eggo said:
Doesn't take much looking on this site to discover stringing 12V in series isn't optimal and actively discouraged. When folks must, the recommendation is to get a balancer.

If you're mixing the same nominal voltage, it can be made to work.

You need to take your 12V and individually charge each to 14.4V for two hours. You should observe NO charge protection events. Then you need to parallel them and hold at 14.4V for 2 hours. THEN you can string them in series. Hopefully, they'll be internally balanced.

Lastly, LFP batteries need to attain "balancing" voltage regularly enough to ensure the BMS can keep the cells top balanced.
Click to expand...
Thanks for the info.
 
Diemjoe said:
I seem to be running into the same problem over and over. It started with 2 Big Battery 12v 170Ah batteries that I purchased based on their specs they could be run in series for my MppSolar 2424 hybrid. Had everything hooked up and they went put of balance pretty quickly. Discussed it with them and they said they no longer supported 12v in series.
Then I went and got 4 12v Rich batteries with the specs say they can be 4 in series or parallel. They are working as a bank of 2 24v batteries for the past couple of years. Now it's time to increase everything for the Cabin that I am making progress on.
I am looking at the EG4 6000 xp and two 48v rack batteries with the hope that I can include the 4 Rich in Series for another 48v 100Ah battery. The specs say they can go 4 in Series. Their customer support begs to differ though. They say they do not balance when in series. Ugh.
They recommend that I look onto a balancer. Does anyone have any experience and/or recommendations? Any concerns about mixing batteries?

Thanks

Don
Click to expand...

Question - do you by chance run the exact same charge discharge cycle daily?

I.e. have a static load connected and consistent charge? Or are you more random?

I'm looking for real world confirmation of some statistical modeling of battery strings. In the model 2 batteries in a string with a static load and charge cycle go out of sync in as few as a dozen cycles.

Where a more random charge/discharge cycle stays in sync better. The more random the better it works.

But mathmatical models never can be trusted until validated and even then you treat them as suspect.
 
Yes if spending money go direct to 48v as a single battery to match the equipment. For the existing batteries get the balancer shown above or consider putting the 12 volters up for sale to put $$ toward an additional 48 volter.
 
robbob2112 said:
Question - do you by chance run the exact same charge discharge cycle daily?

I.e. have a static load connected and consistent charge? Or are you more random?

I'm looking for real world confirmation of some statistical modeling of battery strings. In the model 2 batteries in a string with a static load and charge cycle go out of sync in as few as a dozen cycles.

Where a more random charge/discharge cycle stays in sync better. The more random the better it works.

But mathmatical models never can be trusted until validated and even then you treat them as suspect.
Click to expand...
Right now I am running a 12v cooler size fridge all the time. And randomly charge cell phone and power tool batteries. I occasionally use an Air fryer. I don't keep a very close watch on the 4x 12v Lithium in 24v serial configuration. Especially checking the balance. Might be a good thing to do though.
 
Diemjoe said:
Right now I am running a 12v cooler size fridge all the time. And randomly charge cell phone and power tool batteries. I occasionally use an Air fryer. I don't keep a very close watch on the 4x 12v Lithium in 24v serial configuration. Especially checking the balance. Might be a good thing to do though.
Click to expand...

So you’re tapping one battery in a string to provide 12v loads?

That in itself is causing the unbalance. A buck converter from 24v down to 12v is ideal.
 
740GLE said:
So you’re tapping one battery in a string to provide 12v loads?

That in itself is causing the unbalance. A buck converter from 24v down to 12v is ideal.
Click to expand...
I do have 24v to 12v down converter. RICH and ShopSolarKits are saying they don't support the batteries being in series. SSK also says they haven't had success using external balancers either. So we are trying to work it out.
 
Thanks everyone for your input. I have been going back and forth with shop solar kits. I think I mentioned they have not had good test results with the balancers over time. Waiting to see what they can do. Will update with how this all works out.
 
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