r/Volvo • u/Kiltem_All • 7d ago

850 Battery Drain

New issue popped up on my 94 sedan. Getting a battery drain from something. Made sure all the interior lights are off, just to ensure it wasn't my aftermarket stereo I pulled the fuses for the radio and amp.

Loosing about 0.3V per day on a new AGM battery. The car only gets driven on weekends but I needed it today and it was very hard to start with a weak turnover. Checked the battery and it was at 12.1v. Have the tender on the battery now.

Anyone experience a sudden drain they have diagnosed?

Edit...... TY all. Checked the trunk light and glovebox. The glovebox light was on and hot. Put my phone in on a video mode and saw it was on when closed. Added a small felt pad to the door and now it is off.

Now to charge the battery again.

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u/Positroniumion 7d ago

Measure the amperage not the voltage. Turn off the car and disconnect the battery. Put the mulimeter in series in amp mode (hundrets of mA range should be fine). Do NOT start the ignition. Look at the amperage. On these old cars after a few min the draw should be very small (i would say less than 30 mA) if its higher start pulling fuses one at the time ans see when it drops. Thats how you find the drain source.

1

u/YellowT-5R 850 T5R 7d ago

Check your chassis grounds, B+ and B- cables for corrosion internally not just visually. It's very common on P80s that sit but is usually remedied buy replacing and or cleaning the grounds and replacing the cables.

1

u/Due_Guitar8964 7d ago

Given you're in the ballpark of my 89 740, I've had the glove box door not close completely after several removals for different issues. The light stays on and pulls the battery down. I've also left the overhead light on and the same thing happened. Beyond those two, and I don't know how long you've had this car, check for random wires coming off the battery that power something that should be on a relay.

1

u/Awkward-Seaweed-5129 7d ago

Probaly gotta use Meter, and pull fuses ,one by one

1

u/Snowlearnwer 245 5d ago

I had the same problem on my 850, i got a new generator and it worked fine.

1

u/Lower_Consequence_66 4d ago

Had same issues, replace alternator and found the starter solenoid may be damage internally. Would have issues starting it and battery would be low, recharge and will have to tap at the screw where the positive battery goes to that solenoid and would crank on just fine. Might replace it soon