My 93 940 turbo ran the battery all the way down to where the dome light was very dim for no apparent reason. So, I charged the battery, and put a volt meter on the terminals while the cars was running. I had 14.0 volts at the terminals. So I thought, cool, it must have been the dome light left on or something.

So, I drove it, and the headlights are as bright as usual, everything electrical seemed to have as much power etc. I ran everything at full power, blower, lights defogger, heated seats etc. Checked the voltage at batt again, and it was approx. 13.70-75.

So, now I am wondering if it is a battery issue (1 1/2 year old volvo batt) or the alternator because it isn't closer to 14V (200.00 with core at eeuroparts.) I posted this earlier, but it appeared to be lost so forgive if this is a re-post. Any help is appreciated.


Pittroj

BTDT- Most probable cause is alternator. In particular, a brush in the alternator, making intermittent contact, enough to put out the 14.5V but not enough to put out the current needed. With car off, pull negative cable and then pull the two screws that fasten the regulator brush assembly to the alternator.
You can then pull it out and check it. You can stretch the spring on the most worn brush and reinstall the reg and the cable to drive down to parts place to get another regulator, an order of magnitude cheaper than another alternator. You can also buy the replacement brushes on line if you are handy. If you keep driving on the battery, all your cars electronics shutdown the engine at about 9 volts.

Vigilante, (I like the name, we need some vigilante's out there nowadays)
Thanks for the reply, I have soldered brushes in before on my 1980 242. I am waiting now to see if the batt goes dead on it's own again. But, in the meantime, I will pull the regulator out of the alternator.


Thanks, Jeff

One other PS, the car should set for two weeks without running down a good battery; however, if you have a sneak current leak in the car, you will need an ammeter to finds it even if it's in the regulator. To test battery, go to autoparts store that sells them, they have a discharge rate tester that will find a bad battery and the test is usually free. If, after the battery and alternator checks, the battery still runs down, its time to trace by pulling fuses to find the draw.

Vigilante,
Now, after letting the car sit for 4-5 days, the car cranked, but seemed to turn over slower than it should. I did not start it all the way up, but it did not spin the engine as fast as usual. I will load test the battery, and pull the regulator and check the brushes.

What is the procedure for the pull the fuses method for finding a circuit that may be drawing current?


pittroj