I'm completely frazzled about this one, hoping someone can help me out here.
I was driving out for lunch today and noticed my battery light come on (Ok, I know the light actually indicates the alternator NOT the battery, but anyway..). I got back to work with the light still on, checked all the connections (all good), and started the car again. Battery light still on... I drove home (worried about conking out the whole way), and lo and behold, the light turned off part way home.. Then promptly turned back on again when I slowed down and stayed on all the rest of the way home.. Decided to get a rough idea of how bad it was when I got home. I turned off the car, and left the headlights on for about a half hour. Came back out to start it and it started just fine - light still on. I then turned on the defrost, AC on max, radio, headlights, all internal lights, hazard lights, and played with my power windows. No indication of any power issues/no dimming lights when I turn things on and off, etc.
Now the wierd part: I revved the engine up to about 3000rpm and the light went out. As soon as I took my foot of the gas and the RPMs dropped, it turned on again. What the hell? My alternator is "sort of" working?
Two other things: The battery is only 2 months old, and the alternator belt is fine and snug.
Any ideas? I don't really want to spend $300 on a new alternator if it's just a glitch.

 

This typically means your alternator is going bad. It happens intermittently because the brushes are worn down so they barely touch the slip rings now.

If you have a 98 or so model (not sure exactly what years were affected) check for the common frayed wires in the harness behind the engine problem.

Measuring the voltage at the battery at idle with the lights (but nothing else) on should have 13 volts or more. If not, your alternator is not working.

 

For about $100, you can purchase a rebuilt alternator with a lifetime warranty from AutoZone.

 

I am having the exact same problem with my 2001 civic now. It has been going on for a month and a local garage has told me everyhting is fine with the alternator too. This is occuring more often now, so I am assuming that my alternator is on its last leg. Did you ever get this fixed on your car? Was it the alternator?

Thanks,
Matt

 

I have sort of the same problem with my 91' civic (5 speed manual). Last week my I turn the key and got nothing. No engine, battery, brake light on the dash. Nothing, I get a jump and everything fine, I go to work and when I leave the car starts up with no problem.

*(this has happen twice before over the last two months)*

Then I go to work to day and the car starts up fine, after driving for about 15 min on the beltway my battery light comes on for the first time. It stays on for a few seconds goes off then comes back on again. I drive another 5 min and it goes off. When I left work it starts up fine, I got home ready to park, put the car in reverse and I stall. Tried to crank it back up and nothing again just like last week. I just bought a new battery in Dec. 07.

HELP!! If the battery is fine what else could possibly be the problem?

 

Since the lights on the dash don't even light up, you probably have a loose connection at the battery terminals. When you put jumper cables on, that bumps it back in place and the car works OK for a while until it comes loose again.

 

My problem was my alternator. I bought a new one for $165 and put it in myself in about 3-4 hours. I have to re adjust one of the belts as it squels occasionally but definitly fixed the battery light problem. The local auto parts store conformed my problem by running an alternator test and it showed my 70 amp alternator was putting out 30 amps. Not good. I had quotes to replace the alternator around $500, the difference was their part was almost $300.