Unwanted powered circuit

[gregfox]

 

[Audioguru]

You have the batteries in series but the chargers are in parallel.
Then the chargers do not charge and the switch does nothing.

You need a charger designed to charge at 8.4V which is two Li-PO cells in series.

 

[Bluejets]

You have the batteries in series but the chargers are in parallel.
Then the chargers do not charge and the switch does nothing.

You need a charger designed to charge at 8.4V which is two Li-PO cells in series.

Exactly and many of those charge modules do not have floating output but rather common negative.
So big bang perhaps.

 

[AnalogKid]

IF the charger modules are a variation of a non-isolated buck regulator, then there is a clear power path with the switch open.

But ...

Without knowing anything about the charger module, your question is meaningless and impossible to answer. Please post information about the modules: manufacturer, model number, website - anything.

ak

 

[gregfox]

Thanks all, I configured a charger module to charge 8.2V and now it seems to work great. The only question I have is what about balancing? The modules don't have a provision for balance. If I closely match the batteries would that work?

 

[AnalogKid]

I configured a charger module to charge 8.2V

"A" charger module? What about the other one?

ak

 

[Audioguru]

A single Li-PO cell is fully charged at 4.20V and if charged higher then it might explode or catch on fire.
A very cheap multi-cell Li-PO charger does not balance-charge and matched cells can change with time and become unmatched. Then the weakest cell overcharges and explodes or catches on fire. But you saved a few dollars and will get a good show by buying a cheap unbalanced charger.

I saw a Li-PO explode and catch on fire in an RC model airplane. The fire was impossible to extinguish. Luckily it was outside. The charger was a cheapo from ebay.

My local hobby store sells low cost balanced chargers for Li-POs.

 

[gregfox]

I removed it.