I'm building a battery pack for my portable speaker, and I'm using a random collection of second hand Li-ion cells.
I'm going to have cell phone batteries with differing capacities and also 18650 cells.
The 200W amplifier accepts between 12V and 24V, so at 24V it needs about 8.7A. I also have some low power stuff there, so 200W should be sufficient any way (yeah, I know it's overkill.)
The phone cell's discharge is close to 2A, 18650's discharge can be more than 10A. However BMSs from china are mostly for lipo batteries and their enormous discharge rates of 10A and are too high for these cells.
I'm planning to use per-cell protection of overdischarge (2A or 3A)
I could use one 18650 and one phone cell on parallel, and put those "combinations"
I know, that this will cause uneven SOC, but if each cell has its own protection, this does no harm. only shortens battery pack's "life".
Is there a way to limit discharge current of balancing BMS?
And how do I charge such a pack?
Would it be better to make, say, 3 3s packs instead of 1 9s, so I could charge it with lower voltages?
I have played with Li-ions before, but there are too many question marks for me at this moment, so I had to ask :D
Thanks in advance.
Okay, i hear you. I have good amount of those batteries, so i can form packs of identical batteries. so that is settled.
I plan to use overcharge and overdischarge protection per cell (2A or 3A overdischarge limit), so if the cell would be subjected to too much, the protection will kick in, and shut down the pack.
Even though it may not sound like it, i'm doing this with safety in mind, and all the packs i'm creating will be put on fireproof bags.
I may have given an image, that i know less about this subject than i actually do, sorry about that.
So to clarify, questions revised;
-do li-ion packs need a certain charger in addition to excisting BMS? (my lipo battery pack needs, as it doesn't have any electronics in it)
-can i limit the overdischarge/overcharge current of BMS?