Cell Balancing Idea regarding Contactor

[curiouscarbon]

Hello,

This idea probably has some flaws that make it not suitable for various situations, maybe all situations!

Main contactor requires current. Why not supply this current from a device that draws from highest voltage cell or something?

Issues: isolation, safety, failure modes

eg one mosfet per cell plus a capacitor and inductor or something. boost voltage to contactor and the losses are still there but now the current is doing an additional task

thanks

 

[MisterSandals]

Why not supply this current from a device that draws from highest voltage cell or something?

How many amps does the device need? Is there more than the 24awg balance wire involved?
And how many volts is the device expecting? I hope its 3.2v because thats what a cell has.

 

[curiouscarbon]

however many amps the contactor needs; the idea is to draw energy from the highest cells only, not the whole pack. this would balance the pack.

once cells are balanced, maybe just switch back to a mode that draws from entire pack as in usual case

something like this step up regulator on the output stage to supply 24V https://www.pololu.com/product/2569

it requires 2.9 V minimum and can draw 5A

3V x 5A = ~15W available with one

so probably want to have more than 24awg wires at that point

new downside: need more conductor for balance leads