Universal Robots Forum

UR3 Controlbox restarts during battery use


I use the UR3 in a car and have to supply it with the 12 volt battery. Therefore I use this inverter. Its rated for 300W continous load, 450W for 10s and 600W for 2s. In normal use with AC power i rarely need over 100W, so i thought it should be sufficient.
But if i try it, the controlbox powers up until 100% and then it switches itself off after the fans start. The inverter does not show any error (should beep if overloaded, does not restart itself).

Does anyone have experience with a similar application or know where the error lies?

Thx for any help!

I use a 500W, 1000W peak inverter and it works fine now.

Hi @andy.reinartz,

From your description, I am assuming that the controller will have one short current peak where the voltage output of the inverter will drop. The short duration is enough for the controller to reset, but the inverter will not notice it was overloaded for a short moment.


We have been using a 2000W inverter on a 12v car battery successfully also. We tried with a 350W before and had the exact same issue, after reaching 100% the CB3 would shutdown when load testing the supply.

One note is a high pitched whine coming off the CB3 when running off the inverter, that we dont see when running off regular mains supply. Likely the inverter is quite noisy but we are concerned that this might damage the internal CB3 12V/48V supplies…

For now not had a single issue running off battery power though.