964 battery drain

[986 user]

1990 964 C2.....replaced my second red top optima under warranty last thursday. Started checking the obvious culprits and discovered the eng compartment light was not turning off. It just got a little dimmer when depressed. Switch must be bad. Took out the bulb and am hoping that solves the battery drain problem.

[porterdog]

The trunk, engine, and I think glove box are all interconnected. In my car the drain was traced to a bad glove box switch.

[Jim Richards]

When my 964 was killing batteries, I bought a clamp-on DC ammeter to monitor the battery's current drain while I pulled fuses one-at-a-time to isolate the various circuits. In the end, it was my climate control unit (CCU), which had a failed transistor that kept a small fan running on the CCU. It was drawing enough current to kill the battery in about 2 days. Now I can leave the car sit for a few weeks without problem. Good luck with your troubleshooting, 986 user.

[964TargaC2]

mine was the door switch...leaving the window circuit powered..

[iamtheari]

For those who have diagnosed 964 battery drains with an ammeter, how much current was the car pulling before and after your fix? In other words, what's normal?

[matt demaria]

Normal is about 15ma.

[Traveller]

Originally Posted by 986 user

1990 964 C2.....replaced my second red top optima under warranty last Thursday.

That is why it is a good idea to have an in-car voltmeter connected to the battery.

It'll give you an indication as to what is happening to your battery long before it is gone.

[Newsboy]

I have one that plugs into the citrate lighter. Just po in in from time to time to check battery condition Also good for checking alternator voltage.