Lipo charger, Battery and Arduino

Hello :)

Can i connect a lipo charger to an battery, which is powering an arduino (Pro Mini 3.3V)? or is there a problem? The battery is connected to the RAW Pin, so i thought there wouldnt be a problem connecting a charger to the battery, which is connected tho the Raw Pin then.

Thanks :)


All battery charger interface circuits have a method of disconnecting the load while the unit is charging, with the exception of mobile phones. Most other devices (like an RC Transmitter, disconnects the transmitter when the charging cable is connected. The method used to do this can be as simple as a round dc power connecer (2.1 to 3.5 mm) with a contact that opens the connection to the load when the charger plug is plugged in or a circuit that detects the charger voltage and switches the load power transistor off when the charger is plugged in. You have to decide which route you want to take, the simplest , or a more complex circuit.


The above charger appears to charge without disconnecting the load (based on the SCHEMATIC

Note: The schematic is drawn contrary to normal convention of the power source entering from the LEFT and the LOAD on the RIGHT. It shows the power source on RIGHT, and the power direction is RIGHT to LEFT (reverse of the normal convention of LEFT to RIGHT).

When you don't draw a lot of current, you can run the Arduino from the Lipo cell while charging.

But there are many things you have to know to do it safely.

Sometimes a Lipo battery pack has a protection circuit board inside. That is prevent shortcut, overload and too low voltage. With such batteries, the charger doesn't have to stop charging when the battery is full.

A good charger will stop at 4.2Volt, because that is the maximum that a Lipo cell can have.

If you keep the Arduino running with an empty battery, the Lipo cell gets damaged below 3.0V. That might cause internal shortcuts and that might cause dangerous situations.