Sporadic Dead battery 2001 SL1

My son has a 2001 Saturn SL1… 96,000 miles. In early November we put
new battery in his car because he would have to jump start it ever
time he wanted to leave. After two weeks, he started having th
following problem: About once per week he will go out to leave fo
college and the battery will be dead. Last week when it did it, I put
volt meter on it and it had less than 7 volts (my memory can’t recal
the exact number ). No lights, horn, nothing at all.
We hooked up to a portable power pack and it jumps up to 12 volts an
starts right up. Once running it is upward of 15 volts.
We took the battery back to AutoZone. They charged it for 30 minute
and then tested it. The battery is good. We thought maybe the amp wa
staying on so we unhooked the main power cable to it. Today it die
again….? No alarm or other added equipment.

Mar

 

Sounds like the alternator is bad so it is not charging. The "new" battery
ran down ...

Bob

 

15 volts is a bit on the high side. 13.8v is optimum. Maybe a problem,
maybe not.

Once the battery is charged to the proper level, turn off engine and
all accessories, dome lights, etc. Disconnect either battery cable.
Using an amp meter across the open circuit, check to see what kind of
draw it has. My guess is that it should be below .1 amp. Much more than
that, will draw down a battery in time. Check to be sure your glove box
or trunk light is not staying on. You can do the same thing with a
voltmeter but I prefer an amp meter for accurate readings.

Sometimes a defective alternator can cause a draw when shut off. That
would show up when doing a draw check.

If you find an amp draw with everything shut off, you need to start to
eliminate circuits by pulling fuses one at a time. Even pull relays one
at a time while watching the meter. Eventually you will get to the
bottom of it.

James

 

Have the alternator checked out, it could be bad. Also, if you have a Delco
battery, get rid of it and get another brand, they are troublesome.

marx404