1996 850R Battery Dying Quickly

wackenhut · Post by **wackenhut** » 13 Apr 2016, 21:41

I have a brand new sears diehard battery installed in my 850R and I notice that if the car sits for about a week or so it loses charge real fast. One thing i may note, the head light switch is kind of interesting in that if the light switch is left in the on position, when the car is turned off the headlights go out and there is no indication that you left the switch on. I am thinking that this may be the culprit. I do try my best to remember that I turned the switch to the off position before leaving the car for the night, but it is easy to forget. Has this been an issue for anyone?

Thank you.

Post by **scot850** » 13 Apr 2016, 22:13

You can leave the light switch in the on position with the ignition on. The side-lights will stay on though if you leave the light switch in the middle position between OFF and ON.

Sounds like something is drawing down the battery. Run a draw down test and pull each fuse in turn to find which circuit has a parasitic draw. Then eliminate each item in the circuit.

2 favorites are the glove box light staying on even with the door closed and in a sedan the trunk light staying on.

Neil.

Azik09 · Post by **Azik09** » 14 Apr 2016, 06:35

Is there an original radio installed or not?

wackenhut · Post by **wackenhut** » 14 Apr 2016, 07:46

Yes, there is an original radio.

Sommerfeldt · Post by **Sommerfeldt** » 14 Apr 2016, 07:47

scot850 wrote:2 favorites are the glove box light staying on even with the door closed and in a sedan the trunk light staying on.

Neil.

This. Certainly the easiest to start with.

Can be very hard to see if the glove box light stays on, and in a week, it'll certainly tap your battery of juice. The bracket thingy in there gets a little wobbly over time, and the door pushes the whole thing in, instead of just the switch.
If your headlights are off, they're off - that's the good thing about lights - you can tell when they're off or on, by there being light or not.

- S

wackenhut · Post by **wackenhut** » 14 Apr 2016, 08:01

What is the best way to tell if the glove box light stays on or the trunk light?

Post by **theWIFES_S70** » 14 Apr 2016, 08:10

Here's a good video on doing a parasitic draw test. (Which hopefully, you will not have to do!)

The easiest way to check the glove box light and the trunk would be to press (or is it depress?) the little levers that are supposed to shut off the lights. They should shut off at the slightest touch. And open up the rear seats and see if the lights are on...

Post by **BEJinFbk** » 14 Apr 2016, 08:22

wackenhut wrote:What is the best way to tell if the glove box light stays on or the trunk light?

Start recording video with your phone.
Place phone in glove box.
Close glove box.
Review video.

Post by **polskamafia mjl** » 14 Apr 2016, 08:48

wackenhut wrote:...if the light switch is left in the on position, when the car is turned off the headlights go out and there is no indication that you left the switch on.

That's how it is supposed to work. That way if you accidentally leave your headlights on you won't kill the battery. You need to test for parasitic draw as mentioned above.

theWIFES_S70t wrote:Here's a good video on doing a parasitic draw test.

I love Eric The Car Guy!

bugs11 · Post by **bugs11** » 14 Apr 2016, 08:55

Might be your glove box light. The light in the glove box would remain on when the car was off and drain the battery on my 96 850. I removed the switch assembly for the glove box light. No more dead battery.