1979-1993 & 94 Conv [Subscribe to Daily Digest] |
 | [Main C900 Bulletin Board | BBFAQ |
Prev by Date | Next by Date | Post Followup ]
Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
Re: Battery Drain Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Mon, 6 Dec 2004 06:27:28
In Reply to: Battery Drain, Kevin Newell, Sat, 4 Dec 2004 11:41:34 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I'll start out by saying that most battery drain problems aren't battery drain problems. Most times when a car won't start after sitting only a week, it's usually due to a weak battery. It can also be due to a weak alternator (actually, voltage regulator) that doesn't charge the battery well. In the case of a bad VR, you can go through a string of batteries. So if the battery is over 4 years old, think about replacing the battery, especially if it has been discharged a bunch of times. Car batteries permanently lose some of the capability to fully charge even with only one full discharge. Repeated full discharges kill batteries. Next, make sure you've got a decent charging voltage - at idle, you should be seeing at least 13.0 volts on the battery.
OK, but maybe it is a drain. How do you tell? Yes, use a meter, but there are tricks. One thing to know is that when you disconnect and then reconnect the battery, you get a current spike as many things charge back up - and a good example is the dome light, which will usually come on for a bit.
So here's the drill - get a piece of wire - it doesn't have to be fat, just some wire. Remove the clamp from the Negative battery post. Jumper the clamp to the post with the wire. Then connect the meter, set to measure current, between the clamp and the post - in parallel with the wire jumper. Wait a bit, usually about a minute or so until the dome light goes out. Now, remove the jumper. Measure the current? Why all this? Because the inrush current when you reconnect can be pretty high, and you could pop the fuse inside the meter. The inrush current could be a few amps, and you're going to want to measure on the order of milliamps.
Of course, make sure the doors and hatch are closed. I'm not sure if the 900 has a hood switch - if so put something heavy on it to simulate the hood being closed.
A reasonable current drain is 20-30 milliamps (ma). That is pretty normal for the clock, radio, and alarm system. That drain won't kill a good battery even after a few weeks. Try locking the door and setting the alarm - if you do lock the door, make sure the jumper is in place, as the current for the locking system may blow the fuse in the meter. Again, the quiescent current should be in the 20-30 ma range.
If you do see an excessive current, which would be on the order of 75 or 100 ma or more, then start troubleshooting. One trick is to remove fuses, one at a time. Actually, remove a fuse, and then after measuring the current with it out, replace the jumper, and stick the fuse back in. You don't want to end up with an empty fusebox and a pile of fuses. If you see the current suddenly drop, that's the circuit. This doesn't help with inline fuses not in the box - the one behind the radio, and most likely, in an aftermarket alarm.
But if you're only seeing 30 ma or so after all the current loads quiet down, then I'd say it's a battery or alternator issue.
posted by 192.249....
, Mon, 6 Dec 2004 06:27:28 <-- Viewing This Message
, Sat, 4 Dec 2004 12:43:37
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
