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Re: Battery goes dead. Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Tue, 11 Mar 2003 10:58:13
In Reply to: Battery goes dead., Tino, Tue, 11 Mar 2003 09:45:02 Members do not see ads below this line. - Help Keep This Site Online - Signup |
A battery should last longer than 2-3 weeks without running. However-
Every time a battery is fully discharged, it loses life. So even a new battery that's been fully discharged a few times won't hold a charge as long. Something to keep in mind. You can easily charge a weak battery, and it'll hold a charge fine for a few days, but go dead shortly after.
You definately don't have a short. A true short will either blow a fuse or drain the battery in short order, accompanied by smoke. Normal battery loads when the car is off are the clock, radio, fuel injection, and alarm system, if any. The clock is good for about 10-12 ma, and the same is true for the radio and fuel injection. 10-20 milliamps of draw is normal, and shouldn't pull a good battery down in 2-3 weeks. A weak battery is another matter.
Of course, check for lights - is the trunk light staying on?
To test for current draw - remove the negative battery cable from the battery post. Connect a wire jumper from the cable to the post, and then connect up an amp meter between the battery cable and the post. Look for a push button near the grill that the hood would hit when closed. SOme cars have a button there as part of an alarm system, or to drive an underhood light. If there is a button, put something heavy on it. Yes, the meter will read zero. Wait about a minute, then remove the jumper. You will now be reading the quiescent current drain.
Why the jumper? When you first re-connect the battery lead, a bunch of devices will power themselves up, drawing a lot of current. Depending on your current meter, it could be damaged. Also, the interior lights may come on for a bit.
If you read less than 25 ma, then that's normal. If you're reading higher, pull fuses out one at a time and see if it impacts the reading. Put the fuse back in after you pull it - and you might see a current spike putting it back in.
I suspect you won't see more than about 20-25 ma, and the problem is a tired battery.
Here's a trick - wash the battery with a solution of water and baking soda. When the battery outgasses, it deposits a little battery acid on the outside of the battery. This combines with moisture in the air and dirt, and creates a poor conductor on the outside of the battery. This can actually create a small discharge path on the surface of the battery, one that would discharge the battery even if it were disconnected. The baking soda neutralizes the acid and cleans the battery. It can't hurt, and you'll end up with a sparkling fresh battery.
posted by 192.249....
, Tue, 11 Mar 2003 10:58:13 <-- Viewing This Message, Tue, 11 Mar 2003 15:43:37
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