Power supply for 18 servos and a Pi Zero

[YaytayAtHome]

18 Servos? Has to be a hexbot

Hi,

If I try to power 18 servos and a pi zero from the same battery (7.2V 3000mAh NiMH) am I heading for a world of pain?
Would it make any difference if there are two buck converters - one for the pi and another for the servos?
Should I just give up and run a second battery for the Pi (I have a 6V 2500mAh receiver battery somewhere, but there isn't much space on the hexbot chassis)?

Jim

[mattmiller]

If I try to power 18 servos and a pi zero from the same battery (7.2V 3000mAh NiMH) am I heading for a world of pain?

Yes

You need one battery for your Pi and another battery for your servos

Your PiZero will last quite a few hours with quite a modest USB charger battery

[OutoftheBOTS]

I power this many servos and a RPi off same battery all the time with my robots.

I do always use a separate buck converter for my RPi than any motors or servos because of the noise that they make can upset electronics.

The biggest thing is that you will need to make sure that your battery can supply enough amps to power all this. You will be able to look up the specs for the servos and see how many amps each servo needs the add it up and also add the RPi needs on top. Then realise that the buck converters are not 100% efficient and also use a little power so add an extra bit to get your total needed minimum amps. Then check the battery max discharge rate, unfortunately they don't tend to quote discharge rate in amps but rather a C rating which you multiply the C rating by the amp/hr rating to get the discharge amps rating.

I tend to use RC hobby LiPo batteries as RC hobby is very competitive prices and crazy high discharge rates (often higher than 50 amps, careful don't short a 50 amp battery you will get nuclear meltdown) that always tend to be well above anything that I use for robotics.