External battery charging port safety off.

[MikeLemon]

Hello,

Some of my project require a charging port out that is connected directly to the main battery and I'm concerned with that sins some metal objects may simply short the battery out directly by accident or something so I started working on some protection circuit for that and found out there might be a potential for that to also be a reverse polarity protection circuit but came across some problems here is the schematic:



I'm concerned with both sides of the circuit being live.

What could be the solution for such a thing?

Thanks for helping.

[Zero999]

That's the standard MOSFET reverse polarity protection circuit.

It should prevent the battery voltage from appearing on the connector, but how do you ensure the battery is properly recharged? Normally the battery charger is built-into the equipment and the external power supply just provides a constant voltage.

[MikeLemon]

Ok so, you say if I connect this circuit everything would go as expected?

And I ensure the battery is properly charged by having a BMS constantly connected to it with the balance ports and a standard 10S li ion charger but you said something interesting, you said those chargers only provide constant voltage? just like any other regulator?

I'm looking for a solution to be able to maybe design it my self but I realy don't understand how complicated or expensive that would be.

say I want to charge a 10S battery with another 10S battery. How'd I do it?

[plazma]

This is a circuit I designed for a divelight charging port. The TVS diode and ferrites are for ESD protection.

[MikeLemon]

Hi,

Looks good but seems like it takes too many components for such a simple task wouldn't be possible to do what I mentioned with a single transistor?
What's the explanation for having so many FETs?

Thanks in advance.

[plazma]

You can buy the FETs in double package. The FETs are in pairs so they don't leak through the intrinsic diode. So skipping the ESD protection you only need two double FET packages and four resistors.

[MikeLemon]

Ok...
Thinking about it the max current should be around 6A but what fets do you recommend for these kinds of current at around 20V?


Also why not use a single one again?