Battery ground disconnect and overcharge

[Steve Darwin]

I know almost nothing about batteries and alternators, but here goes… Arabella has two lead-acid batteries. Battery #2 became dislodged and the heavy-duty ground wire that goes from its negative terminal to that of battery #1 came away, but the ground wire from the terminal to the battery switch stayed attached. We’d been motoring with battery #1 engaged and didn’t notice the problem till we got back to the mooring (no battery indicator light when the switch selects #2, no needle movement on the battery tester for #2, though all was normal for battery #1). After re-attaching the ground to #2, everything seemed ok except that now the battery tester shows that BOTH batteries are over-charged. Did I blow the alternator/voltage regulator – or is this a temporary problem? If the voltage regulator got fried, how can I determine that? Thanks for any advice. - Steve Darwin