I have a 0-30v, 5amp power supply with an amp meter on it, I've used it in the past on the Stahl excavators to measure the amp draw of the pump at various psi settings... don't know if it could handle the 850 without blowing a fuse, but I know whatcha mean Neil, a dashmount amp meter is a great idea!
A couple vids of the 850 on the previous page Ben.
One with it in the basement and a couple outside in the bright sun.
Yeah, its working pretty good Martin. Some electronic goodies showed up last week to improve the 850's performance moreso yet for the swing & tracks, and Vario tells me that my track upgrade kit may ship out next wk... probably won't rebuild the 850 till after harvest though, with all this heat the last month, the crop is coming on fast!