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Originally Posted by blue thunder
I'm having the same issue as Idaho biker girl a few posts back. Two nights ago i got in my car to go home and noticed the illumination light on the dash seemed weaker than usual. I drove home with no problem. Today on the way to work the dash lights came on and stayed intermittedly. I tried a test someone said to try. I started the car and then disconnected the negative battery cable and the engine stalled immediately. I was told this means the alternator is bad. Then I drove home tonight with the dash lights coming on and off the whole way. I then got my multimeter and checked the voltage and it read around 12 amps non-running which means the battery is fully charged right? Could my alternator be flaking out and still be charging my battery? I have one ordered for thurs. although I haven't paid yet. Any advice or experience appreciated. Thanks.
Mike  |
You state that the battery measured around 12 amps. I guess that you mean 12 volts. The alternator is very likely to be faulty. However it could be charging, but only on half cycles via the rectifier network, which may keep the battery charged if the load has been light.
The dash indicator lights test circuit, incorporates blocking diodes to eliminate a sneak circuit which would otherwise exist. In an event involving faults within the alternator rectifier network, alternating current is induced on line. The result is pulses of reverse voltage, which pass the blocking diodes in the test circuit and energise the indicator lights.
N. B. Running the car with the battery disconnected is bad news and can cause damage, particularly if the alternator is faulty and there is an over voltage run away. Protection included in the electronic circuits has in your case saved the day, and the alternator voltage regulator is probably OK, but count yourself lucky.
