I built and tested a rover at KSC - it happily drove all over the place at high speed / efficiency - it was like I couldn't lose power.
Got it onto Minimus - after a LOT of tries (couldn't get a rocket into orbit with enough juice left over to get me to Minimus orbit). What I discovered, however, is that my lander wants to lose power very quickly.
Now - it seems to me that Minimus should be getting effectively the same light output from the sun as Kerbal (it's in Kerbal's SOI, afterall). So, why the loss of performance?
(... and no, I'm not operating on the shadowed side of the moon).