95 Honda Accord, 4 cyl

Couple months ago the charging system light randomly came on for a few seconds then went off. Did this maybe 3 or 4 times in a 10 minute drive. Then no issues until last week or so.

Last week I went up to Creedmoor for a physical for my new job and had no problems on the way there. On the way back the light started coming on again. It seemed to be when I would go up a hill in 3rd or 4th gear with the RPMs less than 2000. The next day (Wednesday maybe?) I drove over to campus and the light would come on whenever the RPMs went below 1800 and go off when they went over 2200.

On Sunday I was gonna go somewhere and started it and the light wouldn't go off. So I screwed around with it some yesterday. Battery was at around 12.5 volts before the car was started and didn't increase when it was started. Voltage slowly dropped as the car ran.

I figured the alternator was bad so I took it out this morning and the guy at Advance bench tested it and said it checked out good. So I put it back in and it goes from 12.5 V with it off to about 14 with it running and the light isn't on. On the way back home the light came on again for a few seconds, then went out.

There is a little bit of corrosion on the battery terminals, but I wouldn't think that would cause this. Ideas?

5/13/2008 1:08:39 PM

i would clean the battery terminals first, get the battery checked and then replace the alternator, could be an intermittant issue

5/13/2008 2:12:28 PM

sounds like the alternator, but follow what ^ said.

5/13/2008 2:33:53 PM

i would check all the connections to and from the battery and alternator

5/13/2008 4:42:03 PM

and then drive it drunk into a tree

5/13/2008 4:58:28 PM

It never gets old.

5/14/2008 1:10:43 AM

So there is very light corrosion on the clamps. I've cleaned them a time or two before but shit keeps coming back. Are the replacement cables from Advance any good or should I get some originals from a junk yard?

5/15/2008 6:51:48 PM

Did you smear any light grease on the terminals and clamps?

[Edited on May 15, 2008 at 7:30 PM. Reason : For the corrosion problem not the original light]

5/15/2008 7:29:13 PM

no, but it's in the wires too

5/15/2008 7:46:12 PM

so generic battery cables for cheap, a bunch more for OE cables, or junk yard cables?

5/17/2008 11:38:46 AM

as long as the cables you put on are the same size or greater than the ones you took off, it doesnt matter

5/17/2008 1:55:09 PM

so the alternator finally crapped out and I replaced it. Now I'm wondering if that was the only problem. Is it normal for the voltage to drop from 14.5 to about 12.5 when you come to a stop and then go back up after you get going again?

7/24/2008 7:22:39 PM

On the Denso alternators (which most of them are), a common problem is that the brushes wear out, and begin to make intermittent contact with the slip rings on the armature. What you have described are the classic symptoms of brushes being worn out and making intermittent contact.

If they don't make contact then the armature circuit isn't completed, and the windings aren't excited, and no current is induced in the stator windings, and you get no charging.

Of course, you could always have intermittent failure (thermal breakdown or the like) in the regulator or a shitty solder joint (though these things use some pretty high-temp, heavy duty solder) at the regulator...but my money is on brushes. I've replaced quite a few.

7/24/2008 8:12:35 PM

too bad they don't sell the rebuild kits over the counter. unless i'm mistaken.

7/24/2008 9:30:27 PM