External battery charging when connected to USB-C power

[wingsmelb]

It looks like my ESP32 is charging the external battery when the ESP32 is also connected to USB-C power?

[ESP_Sprite]

You need to be a bit more specific. What hardware are you using exactly, how have you connected it, what battery do you have connected?

[wingsmelb]

You need to be a bit more specific. What hardware are you using exactly, how have you connected it, what battery do you have connected?

Just 2 normal rechargeable battery in a battery holder connected to 3v3 and ground PINs

[ESP_Sprite]

You need to be a bit more specific. What hardware are you using exactly, how have you connected it, what battery do you have connected?

Just 2 normal rechargeable battery in a battery holder connected to 3v3 and ground PINs

...
You're not really helping. What's a 'normal' rechargable battery in this context (LiIon, NiMh, ...?) and what is the hardware on the ESP32 side? Devboard (and if so, which one), custom board, ...?

Assuming something like a DevkitC and NiMh batteries, the 3.3V pin of those types of devboards is directly connected to the on-board LDO, which outputs that 3.3V on that pin if connected to 5V. So it will 'recharge' the batteries (in quotes, because it will just push 3.3V at whatever current the batteries will accept, which is not a good way of charging and can be dangerous to the batteries). You can work around this by putting something like a schottky-diode in series with the batteries, but you'll always have the issue that the 2.4V generated by two LiIon batteries is always going to be under what the flash on your devboard is likely specced for. You'd be better off buying a board that has integrated capabilities to run off/charge a LiIon cell and using that.

[wingsmelb]

...
You're not really helping. What's a 'normal' rechargable battery in this context (LiIon, NiMh, ...?) and what is the hardware on the ESP32 side? Devboard (and if so, which one), custom board, ...?

Assuming something like a DevkitC and NiMh batteries, the 3.3V pin of those types of devboards is directly connected to the on-board LDO, which outputs that 3.3V on that pin if connected to 5V. So it will 'recharge' the batteries (in quotes, because it will just push 3.3V at whatever current the batteries will accept, which is not a good way of charging and can be dangerous to the batteries). You can work around this by putting something like a schottky-diode in series with the batteries, but you'll always have the issue that the 2.4V generated by two LiIon batteries is always going to be under what the flash on your devboard is likely specced for. You'd be better off buying a board that has integrated capabilities to run off/charge a LiIon cell and using that.

Thanks for your reply!