Universal Robots Forum

Error Code C50A26: Voltage present on unpowered 48V power supply

Hello together,

we are currently facing the problem that our UR10 CB3 throws an error at start up when we enter the initialization screen. We are running it with 24V Batteries. We get the error code C50A26 which says: “Voltage present on unpowered 48V power supply”. When we press “restart” and “on” we can simply start the robot (release the brakes) as usual. So this happens once at start up and after trying it again it works fine. So I would suggest it is not a hardware problem but maybe someone knows that problem already and can give us a hint. Currently this error is preventing us from disconnecting the teach pendant and auto starting a program because we need to skip this error message with the teach panel every time on start up of the system.

The attached image pretty much shows our setup but without the standby relay and with 24V batteries (not 48V).

If it was a hardware thing the 48V_RELAY (marked in yellow) would be our suspect but maybe we did not understand the error message correctly.

Thanks in advance and best regards


I have this same problem did you found how to fix it?

Thank you so much!!!

Hi Emoreno,

we did not solve it, yet. But we did find an updated version of the picture above for how to run the UR10 with batteries using the current distributor bord:

Maybe this will do the trick. We will keep you updated :wink: