beef-cake

Okay, so I drove my 89 civic si that's stock in 90 degree weather for 6 hours last weekend, and 30 miles before I got home the battery light went on. Turns out I was losing voltage. So I change the battery with a known good battery. Two days later, battery light comes on.

I bought a new alternator and the battery light went away, or so I thought. I drove to the drag strip and just when I get there, the battery light came on. My voltage was dropping.

So the car keeps losing power and I have to leave it at the dragstrip. We come back the next day, haul the car home and take the new alternator back, they test it, and its fine. My old alternator was also apparently fine cuz they tested it too.
~We think it was a bad ground on the alternator.

I put the old one back in, charge up the battery with a charger, and the car seems fine. Drive 2 hours to my friends house and the voltage stayed at 14.1 the whole time. Next day I drive to an autox, and around 4pm, I notice the voltage has dropped to 10.8.

I put in my other good battery start up the car, it was at 12.1 volts, and drive home, steadily checking the voltage, and it slowly dropped from 12.1 to 10.8 volts.


SO, this seems to only happen when its really hot out, or the car is really hot. Anybody ever see this before? My ELD is working fine, the 12 volt power wire to the power regulator is fine, the main wire from the alternator to the fuse box is fine. So now i'm stuck at testing the FR signal to the ECU and the C wire from the ecu to the alternator I think.

I'm just wondering if one of those wires has a fray in it, and when it gets hot enough, insulation melts and the C wire grounds out or something. Any help would be most appreciated.

JDM_Ej

Only when its really hot... have you checked your main relay? Are you testing for a draw on the system when the car is off?

puredragcrx

Ok, If you have access to an ampere meter test the current draw on the main cables leaving the battery. Do this with the car running and with it shut off. If there is a short taking place in the system it must be a very significant short issue to overcome the alternators amperage and the batteries stored potential, so I would say you likely do not have a short or chaffing problem. If you dont have an amp meter to check this just measure the voltage of the battery when the car is shut off and check it about 6 hours after the car has been sitting with nothing electrical running. If the vaoltage has dropped either something is shorted to ground or some electrical component is on its way out. However if the voltage remains the same (which I suspect it will) Try carrying a voltage meter with you next time the cars light comes on and test the voltage at the battery terminals at that point to ensure that there is actually a problem with the charge system and not the indicator in your gauge cluster.
With those simple tests out of the way some other things to look at would be the voltage regulator circuit. Im speaking for most cars with the description Im about to give and not particularly your car. However it should be very identical as most cars of that era are. Your voltage regulator consists mostly of a few capacitors transistors and in some cases a small transformer. If the windings of this transformer short out they could cause a constant load on the charge system and not allow the alternator to charge the battery properly. I would consider this to be your problem given the description you provided. But start with the easy things like ensureing all electrical components have an excellent ground. I dont mean just look and ensure they are fastened but remove them from there ground point and ensure no corrosion has built up. If you can provide me with more info I can better assist you.

Good luck with the gremlins.

beef-cake

when the car is losing its charge I did check it with a gauge and its not just the indicator light, its actually losing charge. I have checked the battery ground and valve cover ground, I still have to check the tranny and thermostat ground.

Autozone checked my honda alternator and said its working fine, but they did check it when the alternator was cold, however, when using another alternator the problem happened again, so I doubt its the alternator. Both of my batteries i've tried hold charges just fine.

I have to check those grounds, and then also check the wires going to the alternator to make sure one of them isn't working properly when it gets hot.

I did check for a draw when the car was off, and didn't find anything yet, and I did try changing the main relay, but I only changed the main relay when the car was cold, and not when the car was hot and acting up. I will try the other main relay next time the car gets hot and acts up.




Modified by beef-cake at 4:13 PM 6/6/2006

beef-cake

Okay, just found out today that the car doesn't have to be hot to act up. The alternator is only putting out .7 volts at idle, and then 3-4 volts when you rev it to around 4,000rpm. All the wires going to the alternator have been checked and seem fine. I checked all the grounds and there are no voltage drops. I took the alternator mounts, bolts and alternator and wire wheeled and brushed every contact area to make sure its getting a good ground.

Fired the car up and to my surprise the voltage was rising up to 13 volts or so at the battery terminals, I then checked and the alternator was charging, but 10 seconds later stopped, even though the C wire was still at 7.3 volts and wasn't grounded out to stop the voltage regulator from charging.

I think i'm going to take the alternator off my crx and try that on my civic, and my civic alternator on my crx and see if the problem happens again.

puredragcrx

Could the belt be slipping unnoticeably and not spinning that alt to its proper rpms? Also with the alt charge wires diconected check the voltage straight out of the alt. It should be unsteady aroun 12-15v above 2k rpm. If you have a haynes manual look and see if this cars voltage regulator is inline between the alt and battery. If so then look harder at that.

beef-cake

The alternator puts out .7 volts at idle to the passenger side shock tower, where the battery fuse is. When I rev it up to around 4 grand, its putting out about 3-4 volts.

The power regulator isn't inline, its actually inside the alternator. Its not a belt slipping, cuz its at the proper tension and I just replaced the belt for good measure.

puredragcrx

That alternator has too be bad if it is only produceing 3-4 volts dc. Like you said wap the alt out of you other car!

beef-cake

after taking the lower alternator mount, and alternator in one piece out of my crx, I was able to pound out the rusted bolt and bushing, to get the alternator out of my crx, and into my civic.

I heard from a mechanic friend of mine that often people's alternators go out, then they drain down the battery. Then they install another alternator, and it over-works itself trying to charge up the battery that it burns out.

So I think that might have happened with my last one from autozone, or it was just a piece of ****. So I fully charged up my optima battery.

I put in the used one from my crx and the car fired right up, made 14.xx volts and is running fine.

So thanks for anybody that helped, and if you have any problems that sound like this, check all your wires, then swap out the alternator.

puredragcrx

glad to see you got it figured out!!!!