My 1993 Ultra has just started randomly losing power.

It generally does it at time when I have the blinker on.  It’s like someone has quickly turned the power on and off.  It only does or when I’m stopped at traffic lights and it generally it doesn’t stall it just quickly turns on and off.  Yesterday it was idling in the shed and it stopped, all the lights went out for a couple of seconds and then everything lit up again.

It’s like it’s a rely shorting out.  Anyone experienced this?

Thanks

Dave