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Charging A 14s10p battery pack with individual cell management

Johny Ronny

Nov 17, 2017
Nov 17, 2017
I'm building a Lithium Ion Battery Pack 14s10p for a Bicycle.
I see people put BMS in their packs. So I guess I would only need to buy one for 14s and that would work. Wouldn't it?
But some guy on youtube says he does not think BMS's are a good thing. He just monitors battery voltage and then uses a hobby charger to charge them properly. Do you see any flaw in his thinking? Safety? Other?

Also I don't seem to find chargers that can connect to 14s which are not much more expensive relative to a BMS for the same series count. Am I not looking properly, or is there some kind of reason that they are much more expensive?
Some people use a charger for a 7s. But then they have to connect manually the two 7s sets into 14s.

Would it be reasonable to use some kind of relay or mosfet to bridge both 7s packs into 14s once they have been charged? Does someone know of a circuit that allows to connect many 7s packs and then charges them one at a time by switching to the next one once the current pack has been charged? This would allow to let it charge overnight etc. Would it be an interesting project? Would it be too complicated to build with some atmega chip?

Just to be sure my understanding is correct:
- When you have batteries in parallel, they even out, so each has the same voltage. Then what happens if one is broken (permanent low voltage to 1.5V)? Would the whole parallel set of cells even out until they all reach a low voltage of 1.5V?
- Now if i have cells in series, to make sure each battery has the same amount of voltage, I would need some kind of BMS either in the battery pack or in the charger, right?

Thank you very much for having read so far.

If you find any inspiration to answer