Li-Ion battery pack balancer board hack/mod
Good day folks. A colleague of mine gave me a little brain teaser today. He likes tinkering with batteries and create all sorts of packs for various battery operated systems we have set up out in the field and he's currently working on a large 40-something cell pack for use in some traffic monitoring system or something, doesn't really matter, a sh!t ton of 18650s there 
For a higher capacity, he's stacked like 10 cells in parallel and then wired these sets in series to one another get 18v or 12v, can't remember for sure which one, though I think it 18v, so 4 sets. While he was still assembling the pack, he asked me to come up with a clever solution for how we're going to balance these 4 "sets" which are wired in series like in the diagram I doodled in MS Paint (I only drew 3, with 4 cells each, but you get the gist of it). Of course, being knowledgeable about batteries, the good fellow knows what a balancer is and how it should operate, so he offered to give me a couple of these small balance boards with the ultimate goal of modifying one to adapt to the very high capacity of each of his sets.
I was in a bit of a hurry because I was on my way somewhere and didn't have time to mull it over too much or take pictures of the actual board he gave me, but I thought it over along the way as I was driving to where I was supposed to be and realised that this might not require any mods or hacks at all. He asked me to source him some high power FETs and power resistors to create or at least modify one of these balance boards, but that might not be necessary, because we're not seeking to create a high power LOAD which can draw a ton of current in an instant from these batteries - just enough to take away the extra voltage.
For instance, the balancer I linked to has a discharge rate of 66mA if I understand correctly what that value represents. True, with the available capacity being this big at each "set", it would probably take a long time to discharge an "overcharged" set at that small a rate, so he's somewhat correct and I kinda get what he's thinking of - he wants a fast discharge rate to bring the sets to the same level faster...I THINK that's his theory. I understand it to a degree, but I don't think it's actually necessary ! Why beef up the BALANCE hardware just because the PACK itself has a large capacity ? If anything, the CHARGER would have to be beefy to push the amps required to charge such a pack, while the BALANCER only takes care of any possible "excess" voltage on each set at its own pace if necessary.
To better understand how such a balancer might work, I looked up this datasheet for an IC which might be used on such a board: an HY2213. Page 8 shows us how this simple 3-terminal device operates. B1-B5 would represent our sets made up of 10 batteries each, so WOULD you need such a hack or is it redundant and an off-the-shelf solution like this would handle it just fine ? Cheers and thanks.
For a higher capacity, he's stacked like 10 cells in parallel and then wired these sets in series to one another get 18v or 12v, can't remember for sure which one, though I think it 18v, so 4 sets. While he was still assembling the pack, he asked me to come up with a clever solution for how we're going to balance these 4 "sets" which are wired in series like in the diagram I doodled in MS Paint (I only drew 3, with 4 cells each, but you get the gist of it). Of course, being knowledgeable about batteries, the good fellow knows what a balancer is and how it should operate, so he offered to give me a couple of these small balance boards with the ultimate goal of modifying one to adapt to the very high capacity of each of his sets.
I was in a bit of a hurry because I was on my way somewhere and didn't have time to mull it over too much or take pictures of the actual board he gave me, but I thought it over along the way as I was driving to where I was supposed to be and realised that this might not require any mods or hacks at all. He asked me to source him some high power FETs and power resistors to create or at least modify one of these balance boards, but that might not be necessary, because we're not seeking to create a high power LOAD which can draw a ton of current in an instant from these batteries - just enough to take away the extra voltage.
For instance, the balancer I linked to has a discharge rate of 66mA if I understand correctly what that value represents. True, with the available capacity being this big at each "set", it would probably take a long time to discharge an "overcharged" set at that small a rate, so he's somewhat correct and I kinda get what he's thinking of - he wants a fast discharge rate to bring the sets to the same level faster...I THINK that's his theory. I understand it to a degree, but I don't think it's actually necessary ! Why beef up the BALANCE hardware just because the PACK itself has a large capacity ? If anything, the CHARGER would have to be beefy to push the amps required to charge such a pack, while the BALANCER only takes care of any possible "excess" voltage on each set at its own pace if necessary.
To better understand how such a balancer might work, I looked up this datasheet for an IC which might be used on such a board: an HY2213. Page 8 shows us how this simple 3-terminal device operates. B1-B5 would represent our sets made up of 10 batteries each, so WOULD you need such a hack or is it redundant and an off-the-shelf solution like this would handle it just fine ? Cheers and thanks.
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