Will a 20S BMS work for balance charging a 10s2p setup?

I can’t find anything more than a 10S thread on here, just wanna know if anyone has done this or if it will work? will i need 2 10S BMS’s or a balance charger? thanks in advance

If you’re asking about a 20S charger with a 10S battery: no, it won’t work because it’s not 42 Volts. Don’t do it.

If you’re asking about a 20S BMS with a 10S battery, maybe but it depends.

What exactly is the question?

sorry i muddled my words it’s just for balance charging a 10s2p. would a 20s bms work?

Smart bms allow to do It. Can also be done if you know how to modify It. Do not mess with that unless you know exactly what you are doing. Selling It and buying a 10s is the best option. You can even earn some cash.

Yes, but it’s most likely 2x the size of a 10s BMS. What’s the point?

Rojitor beat me to it : )

Most of the time, yes. IF you wire it correctly. I’m sure there are some BMS that won’t, it would depend a lot on the specific BMS

Start from the negative side and leave the extra on the positive end

Any 20s Bms you’d recommend? i want to be able to charge all at once and its less wiring

I have a Bestech 10s 35a BMS, you want it?

You need a 10S BMS

I was under the impression you already had a 20S that you wanted to try to use. If you don’t have one yet, you need a 10S BMS

What battery are you using? Do you have a photo? What charger are you using? Do you have a photo? Do you have a BMS now? Do you have a photo? What cells are you using? Do you have a photo?

Using a 20S BMS on a 10S battery will just mean half of the BMS isn’t being used and is wasted space/weight/money. It won’t charge faster or better.

yeah but if I’m wanting to charge 2 10S’s at the same time in parallel could i do that with a 20S bms?

No ‍ ‍ ‍ ‍

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No. That’s precisely what a 10S BMS does.

so do i just double up the charging cables going into the bms? i don’t understand how i can charge 20 cells all at once with a 10S BMS?

You will be charging them in parallel. You have a 10s BMS for a 10s2p battery, so the 42V are equally divided through the series connection, and the current is divided by 2 for the 2x 10s packs.

Do you need a 10s BMS?


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I have a similar question so I am high jacking the thread. I have 6 4s 5.2ah turnigy graphine batteries wired 3s 2p. Could someone help me figure out the wiring to that 1 BMS could balance all 6 batteries?

Sounds like your doing 12s2p. You need a12s bms. Then search on the forum about how to wire it. One BMS will charge all 6, but you have some reading to do.

You only need one wire per parallel. 10s2p and 10s20p will work with the same bms. Watch some vídeos at YouTube about battery welding.

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the way this works is that you take your twenty cells and group them into the parallel groups they will be in (in you case, ten pairs of two cells). Because they have the same internal resistance, they should discharge at the same rate, and because they’re in parallel they will maintain each other at the same voltage. You then connect the parallel groups in series to form 10s with 2p groups as each “cell” in the series. you can then treat each parallel group as one cell when connecting to the BMS because they are, electrically, one cell.

having two batteries in parallel is electrically indistinguishable from having one large battery. After all, a larger battery is just the same as the small battery but with more chemicals inside it covering a larger surface area with their contact, if that makes sense (i know it doesn’t really but trust me on this - they’re the same)

i suggest you do more reading too, any battery build guide covers this info pretty well