Use lipo balancer on 6v lead acids?

[Vigo]

So I've been curious about this but in several minutes of digging around I wasn't able to find the answer..

Is it possible to use a balancer intended for lithium cells on a string of 6v lead acid batteries? I feel like the answer is "Yes, if each channel can handle having ~8v on it", but i can't seem to nail that down! The ones i've looked at just say things about typical 3.X v lithium chemistries but nothing about a 'max channel voltage'.

Anyone know the answer to this?

 

[sunshine_eggo]

Most lithium-intended balancers range 2-5V. There are 12V balancers, and I expect you can find 6V balancers.

 

[Vigo]

Thanks for the reply. I was being hopeful that i could take advantage of the ludicrously low cost of some of the large-string lithium balancers (24 batteries in my lead acid setup) because as far as i can tell so far, the cost goes up dramatically when you look at things designed specifically for 12v stuff, and i haven't come across anything yet that specifically was intended for 6v (but im still looking).

 

[sunshine_eggo]

Thanks for the reply. I was being hopeful that i could take advantage of the ludicrously low cost of some of the large-string lithium balancers (24 batteries in my lead acid setup) because as far as i can tell so far, the cost goes up dramatically when you look at things designed specifically for 12v stuff, and i haven't come across anything yet that specifically was intended for 6v (but im still looking).

48V? Is it 8S3P.

I had 4S2P 12V for 48V when I was on FLA. Had 8 of those balancers... ~$200. Not cheap.

 

[Vigo]

Yes, 8S3P. I think ive got enough Lifepo4 now that i could just remove this 2700lb lead acid bank from service (on my house anyway) but i still look at it as an opportunity to learn how to finesse good results from mistreated antiques (like i do with cars, my main hobby) so I haven't given up on project ideas like implementing a balancing system, etc.

Thanks!

 

[Consumerbot3418]

Wish I'd thought about checking this forum first, but...

I just ordered one of these for my 48V FLA forklift batteries, not as good as per-cell balancing, but thought it might still be worthwhile. I spent quite a while looking for something that could handle 24S lead acid, and the closest thing I could find was this guy for about $90 delivered from AliExpress. If I knew for sure it would help keep my 48V batteries balanced as they discharge, I'd pull the trigger. Seems like an expensive gamble on something that would probably be difficult to return, though.

 

[Samsonite801]

So I've been curious about this but in several minutes of digging around I wasn't able to find the answer..

Is it possible to use a balancer intended for lithium cells on a string of 6v lead acid batteries? I feel like the answer is "Yes, if each channel can handle having ~8v on it", but i can't seem to nail that down! The ones i've looked at just say things about typical 3.X v lithium chemistries but nothing about a 'max channel voltage'.

Anyone know the answer to this?

You don't need a balancer on lead acid, they have a healthy tolerance for overvolting the cell at 100% SoC, where the cells will naturally hit a peak and balance out when you do a standard occasional maintenance equalization charge.

lead acid equalize charging cycle balances cells - Google Search

www.google.com

 

[sunshine_eggo]

You don't need a balancer on lead acid, they have a healthy tolerance for overvolting the cell at 100% SoC, where the cells will naturally hit a peak and balance out when you do a standard occasional maintenance equalization charge.

lead acid equalize charging cycle balances cells - Google Search

www.google.com

While your statement is typically true, and there's further balancing benefit from coulombic inefficiencies at higher states of charge, a balancer is often helpful.

In my case, I procured 8X used T-1275 that were individually equalized as 12V batteries with before and after testing of reserve capacity with equalization. In short, I paid about $600 for 14.4kWh of used FLA that tested 80-96% of rated reserve capacity.

In operation, maintaining balancing with each of the 12V @ peak voltage was challenging at times. The installation of 12V balancers helped keep them within about 0.05V of each other at peak 48V system voltage.

 

[Samsonite801]

While your statement is typically true, and there's further balancing benefit from coulombic inefficiencies at higher states of charge, a balancer is often helpful.

In my case, I procured 8X used T-1275 that were individually equalized as 12V batteries with before and after testing of reserve capacity with equalization. In short, I paid about $600 for 14.4kWh of used FLA that tested 80-96% of rated reserve capacity.

In operation, maintaining balancing with each of the 12V @ peak voltage was challenging at times. The installation of 12V balancers helped keep them within about 0.05V of each other at peak 48V system voltage.

Seems like it would only be worth it to bother balancing if you had all 2.1v cells in the lead acid bank. Because bothering with doing it on 6v module level, one would still have variance across 3 cells in each battery, wouldn't they?

And if the batteries were matched better in groups to equivalent capacities, they would probably have less drift.

My theory would maybe be to just add more batteries, but that's just me.

I have seen the common BMSs, like JBD and such, say they could do lead acid chemistry in their specs sheets (maybe they need a different firmware, or change some setting), but it's still only on cell level. I've seen the Victron balancers which can do 12v to 12v bank, not sure if someone makes a 6v model though.

Oh I guess there are some like this seen on a quick search:

https://www.amazon.com/Battery-Charging-Balancer-Equalizer-equalizer/dp/B0B5PLKP4F?th=1

 

[Consumerbot3418]

Wish I'd thought about checking this forum first, but...

I just ordered one of these for my 48V FLA forklift batteries, not as good as per-cell balancing, but thought it might still be worthwhile. I spent quite a while looking for something that could handle 24S lead acid, and the closest thing I could find was this guy for about $90 delivered from AliExpress. If I knew for sure it would help keep my 48V batteries balanced as they discharge, I'd pull the trigger. Seems like an expensive gamble on something that would probably be difficult to return, though.

Well, I found a cheaper option and a coupon code for a 24S active balancer that does lead acid (with bluetooth and rs485, and free returns!), so for $66 delivered, I rolled the dice and ordered one. I'm hoping to gain some capacity as it discharges, if it helps keep the weak cells from drooping. And even if I don't gain much in terms of capacity, it will yield some insight in terms of per cell voltages as I charge and discharge. I hope to find a way to tie it to Home Assistant via the Raspi that's already on the DC Solar trailer to talk to the Sunny Island and Midnite, and get some nice graphs and such.

I've done a number of EQ runs on these batteries, but can't get the Sunny Island to target a voltage higher than 63V, and get interrupted by the sun going down. And even if I could set a higher EQ voltage, I hate blasting all the good cells just to recover the few weak ones. I may target them individually with a bench power supply, hold them at 2.6V for 48 hours at a time...