Balancing Batteries

Using Arduino Motors, Mechanics, Power and CNC
#1

I'm aware of the fact that you cannot use two batteries of different voltage in parallel as one battery will try and flow into the other to even out the voltage.

So an idea that came to me - to run them through voltage regulators first (switching buck converters) so that both battery becomes a standard voltage (i.e. 5 volts) and then connect them in parallel, that way both battery will be the exact same voltage (within 0.01 volts or less) which therefore would negate the earlier issue.

Am I missing something here or would this work?

#2

NEVER EVER connect voltage regulators in parallel!!!! You'll probably fry the
entire board.

#3

Does that apply even if you're using something like this?

If so, what is the reasoning?

#4

Voltage regulators in parallel wont current share, and can oscillate uncontrollably..
The only way you can make such an arrangement work, is to disable the voltage sensing from one of the regulators
and connect the sense voltage to the other via a summing network.
But its just not good practice.

#5

Thanks for the info guys.

I had two expensive, high-capacity LiPo batteries and hoped I could parallel them but it seems not, shame really but I’m sure I’ll live.

#6

User a proper Li-Po charger to balance both packs. Then you can parallel them no problem. I do this all the time. I'm pulling over 100amps from each pack when they are in use. You only need to parallel the main power connectors. Then when you charge them, charge them each removed from the circuit, alone, with the li-po charger. In a charge bag, if you like your house.

#7

trum4n:
User a proper Li-Po charger to balance both packs. Then you can parallel them no problem. I do this all the time. I'm pulling over 100amps from each pack when they are in use. You only need to parallel the main power connectors. Then when you charge them, charge them each removed from the circuit, alone, with the li-po charger. In a charge bag, if you like your house.

They are different voltages (and capacities) though. One is a 5000mAh 11.1v and the other is a 10000mAh 7.4v. I'm sure what you're saying would make sense if they were the same batteries though.

#8