I have a yellow top optima on my Discovery and am having trouble, if fully charged and off the vehicle it shows no sign of power loss over 3 weeks. Put it back on the vehicle and it is flat within 3 days, I had the battery checked at a optima dealer and they said it is ok. I can find no problems with the electrics and have done nothing to it to create a problem. Anyone got any ideas before I take it to a auto electrician.