battery dead in morning

[hankeester]

I just picked up a 91' Volvo 240 with 280K miles on it. I'm somewhat familiar with Volvos as I've owned a few in the past. So I drive it from the dealer and let it sit for 6 hours upon purchase. I go to start it and nothing. The battery is new so I'm chalking this up to a slow drain, starter solenoid, or possible voltage regulator.

I jump started it and drove it for 1/2 hour then parked it overnight, same problem. I put a battery charger on it and it says it's fully charged. What are the steps in checking to see where the problem is? I'm going to go put it in neutral to see if it will start, possibly a bad shift lock. After that I will put the multimeter on the battery to see if there's any drainage.

Not in a huge hurring to fix as it's a 3rd car and really just bought it because I love the 240's but any diagnostic info anyone can give on the above would help.

Thanks,
Chad

[hankeester]

one other note, when I have the battery charger on, there is a loud humming noise coming from around the area of the rear drivers side passenger door and when I pull up on the lock the humming changes. I thought these had vacuum ran door locks.
The central locking system doesn't work either.

EDIT: I pulled fuse #8, jumpstarted it, drove it around. I'll let it set for 5 hours and see if I have the problem. If not I suppose I need to look into the central locking system as the culprit.

[billofdurham]

The central locking is electric and could be the cause of the drain.

If removing fuse #8 does not cure it I posted an item here on tracing a parasitic draw.

Bill.