# Electrical – grounding a moving robot

battery-charginggroundgroundingsafety

I'm am designing an external battery pack for a robot, Pepper, a robot by Softbank (I'm am not making the battery itself but the circuit connecting two batteries). I am going to connect a 25V (LiFe-PO4) battery to Pepper's internal (Li-ion) battery and strap it to its back. Due to the delicacy of (Li-ion) batteries I included a voltage regulator. But I also want a ground in this circuit, in case of a short circuit or anything.

The problem is: Pepper is a moving robot, so a real ground isn't possible. I was wondering whether it is possible to use its (small) metal chassis as an earth. Similarly like they do in cars.
(Just wiring the – to the chassis)
Pepper is a robot which is about 1,4m high, and only has a metal chassis in it's base, which is about 40cm broad and 20 cm high

If this is not advisable, is there another way of making the circuit more safe? (I am already going to include a fuse.)

External battery specs:

-Capacity 10Ah

-Output voltage25,6V

-Maximum pulse discharge 55A

-Maximum continuous discharge 15A


Internal battery specs:

-Capacity  30Ah

-Max charge current 8A

-Max charge voltage 29,4V


P.S.
Any other tips about my project are more then welcome