Hi all,

I have a 93 Volvo 850 GLT, and had the battery replaced about 15 months ago. I've had no problems with the battery until today. Today, I pulled my car out and took a very short (less than 5 minute) drive, parked, and then when I tried to leave, my battery was dead. I restarted it with jumper cables, drove around for 15 minutes, and then went back home.

I usually drive my car almost every day, but hadn't driven my car for 3.5 days. I don't think any lights were on, or anything else that would drain the battery. Although, during my short drive my defroster was turned all the way on, as was the "tape" function on my radio.

First, any idea what could have caused the problem?

Second, should I feel safe driving around (i.e. could this just be a one time thing?), or should I take the car in to the shop for them to look at the battery?

Thanks in advance!

 

First to answer your question... Yes, go have the battery tested. They will likely say that your battery is fine but has a low charge. That will cause them to question the alternator, which will scare you because of the replacement cost. About $465. Don't worry!

The thing that you should know is that all modern cars (computer controlled), have a normal-constant battery drain. So, when you park your car and turn it off, the battery has to power several things. Alarm, clock, ecu info, radio info, and maybe a few other low power things. So, if you let the car sit for several days, say 30 days, it will totally discharge the battery. The problem that some people have is that they don't drive far when they do drive. Lets say that your car has a new battery and it 100%. Now you drive daily about 4 miles to work which is 8 minutes. When you parked your car on Friday and let it sit till Monday, it was down to 96%, starting the car knocked it down to 95%, drove it to work and charged it up 96%, let is sit 8 hours - still 96%, started it - now 95%, drove home - charged to 96%. Day after day you do this small drain and because you never drive the car for over 45 minutes, you never charge it back up over 98%. Several months later you now are down to 82%, start it, now 80%, only drove 5 minutes so had no time to charge, let it sit a little while go to start it - dropped to 78% and didn't hold it long enough to start so you let go. Try again now you're down to 75%, not enough juice to start. I say all this to say that you may not drive long enough trips to charge the battery. Now that the temp has dropped, winter time, batteries drain faster (while parked). So these problems are showing up more and more.

Now, your knee jerk reaction would be to start the car and drive it 15 minutes, which will charge the batter up maybe 5%, then park it for 2 more day which will cause it to loose it's charge and not start again. The best thing to do is have the battery charged back up to 100% and start the cycle all over again. You'll be fine. If you want to drive around and charge the battery it can take as long as 3 hours of driving to fully charge your battery.

There is a chance that you do have a faster draining problem but I doubt it. There is also a chance that you have a problem with your alternator but I don't think that is the problem either. The best way to check your alternator is to hook up a volt meter and measure the volts across the battery while the car is running. It should show 12.8v or better. That will let you know that your alternator is charging the battery. It may show 13.4. You can also start the car at night, turn on the lights and while watching the lights, rev the motor a little. If the brightness of the lights change a lot (get a lot brighter), that is NOT good. The should get just a little brighter, but not much.

If you had a car with an OBD-II port, you could hook up a code reader and take a live reading and see what volts the system is producing. I recently had a lady that called me thinking her alternator was bad (because the auto place told her it was) and it was just her driving needs consisted of short trips, not long enough to charge the battery. She left the interior lights on one night, spotted them the next day, turned them off, and let the car sit over the weekend before trying to start the car and the battery was to weak. She got the car jumped, drove 8 minutes to work, after work it would not start, jumped it and drove to the auto parts place where they said her battery was good but weak, then told her that she probably needed an alternator. She called me in a panic about how expensive Volvo's are and I told her to have then charge the battery for FREE. Which they did and she has had no problems since.

So again, get the battery charged up to 100%. If you don't leave any ligths on in the car and it dies again with a month let us know.

 

Thanks for your help, RSPI. Very informative and helpful answer!

 

Start simply. Check the battery terminal connections and cables and their connections at both ends. Test for voltage.
Ed