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battery light

A

ancientsanskrit

Hard-core CEG'er
Joined
Dec 6, 2003
Messages
1,138
Location
Dallas, TX
Car: 1998 Se w/119k miles on the clock.

Anyways, for the last few weeks I have been getting a battery light when starting the car. After about 2/3 miles the light goes away.

Battery: I took the battery out and did a load test on it at my local AZ. It held at 11.xx V under load, and was fine.

Alternator: Has been replaced ~6 months ago. Now, the light goes away, which would lead me to think it can't be the alternator. My commute is about 30 miles one-way and the light never comes back on. Tested voltage w/car running, nothing unusual.

My last attempt was to clean the battery terminals w/a wired brush. Still getting the light.

Another observation I've had is that usually after the car sits for longer periods of time, this occurs i.e. in the morning and when returning to car after work. If I restart the car within a shorter time-range (I dunno, say 30mins/1hr), the light doesn't come on.

Thus, I am wondering if anyone else has any suggestions as to what the culprit may be. Thanks!
 
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Non OEM alternator = wont last long. I just replaced mine with a remanufactored, and I dont expect it to last long, the good news is that it has a lifetime warrenty, and its easy to replace in the zetec so I dont really care.
 
:crazy: Ughh, I replaced the alternator w/an oem replacement.

Just fyi, almost all alternators sold by the dealership are "remanufactured."I even had Bill confirm this with me, as I was completely lost as to how people were making posts about only getting "new units."

Anyways, I'd appreciate suggestions!
 
ancientsanskrit said:
...Another observation I've had is that usually after the car sits for longer periods of time, this occurs i.e. in the morning and when returning to car after work. If I restart the car within a shorter time-range (I dunno, say 30mins/1hr), the light doesn't come on.

Thus, I am wondering if anyone else has any suggestions as to what the culprit may be. Thanks!
Click to expand...
It's a wiring/connection issue. When it is warm, the heat expands the metal (either on wire or connection).

Need to check for chaffed wiring or loose/dirty connections.
 
Have the alternator bench tested at a competent electric shop that specializes in generator repair and make sure that they test the alternator diodes. When the diodes go bad (could be a poor connection thus a heat induced problem) the alternator will still charge but the alternator light will come on.
 
Thank you gentleman.

Does this bench-test the unit to be out of the car?
I should also stress, I'll probably go Tony's method and look at all connections myself, as I don't want to spend much money on this car. Basically, just driving it till it falls apart.
 
The bench test has to be performed on the alternator when it is out of the vehicle. Check with your local parts store and see if they can test the alternator while it is in the vehicle, but make sure it tests the diodes as well. The diodes are located inside the alternator so a visual or wiggle test cannot be performed on them.
 
The "battery light" is not really a battery light. It is a charging system light. It is a very rare occasion for the light to come on from a bad battery. Still, you do need to make sure the battery is good before fully diagnosing a charging system problem.

I don't think a bench test will tell you much. If the alternator itself is acting up only for the first few moments after start up, it may not show up on the bench test. You should be able to test it on the car, although it may take a few times of testing before it goes away to pin it down.

You need to be able to get a volt meter lead directly to the alternator while it is acting up so you can read the voltages at each of the leads coming into the alternator and compare it to the readings when the alternator is fully functioning. From this you should be able to pin down if the problem starts outside or inside of the alternator.

I too mostly suspect the wiring, but it is too soon to tell until you check it out.
 
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