Hobby Robot - Power requirments + Charging

[iansmiler]

Hello,

I have a hobby robot that I built which is currently powered from 4 x Ni-MH batteries @ 2000Mah per battery. I have to remove the batteries from the robot to charge them.
I would like to switch to Lipo power but I do not know where to start... The robot's brain is a raspberry pi zero, and it has two wheel drive motors that operate through a L298n motor driver.

Any help with speccing what I need would be greatly appreciated 

Ian

[glebkooo]

Hi Ian,

(newbie here)

It is hard to say what is the total power requirement for your robot without info about motors and the voltage of a single Ni-MH battery you use.

However, I would start with the following.

Two 18650 Li-ion batteries connected in series will give you a voltage between 6V and 8.4V. That should be enough for powering motors, however, buck converter might be needed.
For powering RPI Zero you would definitely need a buck converter capable of delivering 5V 1.5A. There are plenty of such DC-DC buck converter modules, just peek one that suits the RPI power requirement.

I would use a module based on TP5100 IC for charging. It can handle two 3.7V Li-ion batteries connected in series.
For powering that module you might use a USB charger with PD / QC function that can provide 12V, and a PD trigger module, based on CH224K, for example.