Hello Mark. Just saw your post from TWO YEARS AGO. Sorry. we move slower here in LA than you guys do in CA. Ever figure out what that was? I frequently have to change out my stater (not battery master) solenoid at $100 a pop from Aircraft Spruce. Your theory about it being a capacitor makes sense. Spruce has what looks like a little diode spliced in a feed line for Cessnas. I’m probably going to buy one of those and try it out. Much cheaper than a new solenoid every 6 months, although I have made it a personal challenge to see how hast I can change it out… first was ~ an hour, now down to 12 mins. Would rather correct the problem than improve upon my pit crew skills.