Weird Electrical Charging Problem

Tiny
ROBK
  • MEMBER
  • HONDA CIVIC
I think I've got a tricky one on my hands. My daughter has a 97 Honda Civic HX. Thanksgiving night (of course) she called to say her car wouldn’t start. I drove over to her house and jumpstarted her car. The headlights were repeatedly flashing brighter dimmer brighter dimmer. I checked the battery voltage with my meter and it was jumping from below 12 to nearly 14 volts so fast the meter couldn’t keep up. My immediate thought is that the internal regulator was freaking out. I left the battery charger on so she could get to work in the morning. The next day I swapped cars with her and took the Civic home. I removed the alternator and took it to Advance auto parts. Since I didn’t want to waste my daughter’s limited funds, I asked them to check the alternator on their machine. The machine said it was working fine. I put it back on the car and checked the voltage at the battery – it was approximately 11.5 volts, i.E. Not charging. I drove the car straight to Advance and asked them to check the charging system on the car. They brought out their machine and checked it and said everything was fine. I checked the battery voltage with my meter and sure enough I got about 14 volts. I swore to the guy that only ten minutes earlier the battery was not charging. He just kind of looked at me funny. I gave the car back to my daughter and told to wait and see what happens. It worked fine until the Friday before Christmas; same problem again. This time I just bought a new alternator and put it in. Seemed to work fine, 14 volts at the battery with the engine running. Problem solved, right? Wrong. Last night she calls me to say it wouldn’t start again. I jump start it and the lights are doing the bright dim bright dim thing again. Check the voltage at the battery and I’m only getting about 11.5 volts. Race the engine and the flickering stops and the voltage drops to around 8. What am I missing here? I used to be a mechanic, and I’ve replaced hundreds of alternators over the years. Generally they either work or don’t work. Put a new one on and you’re good to go. Sometimes a bad connection can cause a weird problem, but I don’t think that’s the case her. Any ideas?
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Friday, January 5th, 2007 AT 10:35 AM

6 Replies

Tiny
BRUCE HUNT
  • EXPERT
I'm thinking here. Now let me do it out loud on paper so to speak. First off the replacement alternators from several car parts stores are s-o-m-e-t-i-m-e-s not as good as what you just took off. But lets skip that since you have the exact same symptom again. So. In the fusebox, one of them, under the hood or in the car, is a relay for the starter. I am not exactly sure what type it is, but look for it. Now once you have found it, see if there is another one just like it to swap for a bit. If not, I don't have access to testing info on the relay but I know it can be done. Actually, I have removed the cover off some of them and observed the circuitry and made my own testing with the ohm meter. Anyway the relay is an option to look at.
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Friday, January 5th, 2007 AT 11:03 AM
Tiny
ROBK
  • MEMBER
I'll try that this weekend. But once the car has started, why would the starter relay come in to play?
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Friday, January 5th, 2007 AT 11:39 AM
Tiny
BRUCE HUNT
  • EXPERT
Sorry, I jumped from one person's problem to yours and his wouldn't start. Scratch the relay, no relay on the alternator. However, another thought is the starter switch. Was the alternator a new or rebuilt one?
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Friday, January 5th, 2007 AT 1:59 PM
Tiny
ROBK
  • MEMBER
Well, it was the cheapest rebuilt I could get (daughter's fresh out of school and on her first job). It just seems so strange to have such an unusual and identical problem.
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Friday, January 5th, 2007 AT 2:43 PM
Tiny
SNOWMARK
  • MEMBER
I have a similar problem on my 86 EFI Accord. The alternator checks out good when tested but the dash light comes on and the battery discharges when running below about 4200 rpm, above that the light goes out. Belt, connections and battery are all good.I thought I would change the alternator anyway but I suspect the problem would still be there?Sometimes when I start the car the light is off but comes on later or at a restart
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Wednesday, January 24th, 2007 AT 5:39 PM
Tiny
BRUCE HUNT
  • EXPERT
At the time the alternator light comes on, hook up a voltage meter and read what the power is at the battery.
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Thursday, January 25th, 2007 AT 3:41 PM

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