1. Caleb

    Caleb Loyal Comrade

    @'bant - Thank you for the update. So based on your new battery it seems like at idle with no lights I should be reading 7v. Mine was only reading 6.5v as I remember so something is for sure wrong. I will put the battery charger back on and see what kind of amps it is pushing after charging for a while. Maybe the battery has gone bad on me. Better to rule it out now and know for sure.

    I was thinking a little more about it and when I had the volts tested the reading would increase as revs increased. So that should mean that the generator is producing power but maybe just not enough at the lower rev range at idle? Maybe worn brushes or faulty wiring. My uncle also brought up a question about the capacitor. He explained that a friend of his had trouble with a jeep that ran on points and it was because the capacitor would overheat and cause the ignition to stop working. once it cooled down everything would start working again. I don't know much about the ignition and points yet (still learning) but could the usage of the lights cause the capacitor to overheat causing the stalling issue?
  2. turbofiat124

    turbofiat124 Loyal Comrade

    If I recall before installing the alternator, mine would read the same voltage at idle as if the car was not running (~6.4 volts). The battery indicator light would not light up as long as the idle speed was around 700 rpms. If I reved the engine up a bit, the voltage would increase to around 7.4 volts. I can't remember if the headlamps made any difference. Maybe a .2 voltage drop.

    If the engine started to stumble (such as during a warmup) the indicator would glow.

    What's weird is it seemed the generator would not produce any voltage but the indicator lamp would not glow as long as the RPMs were above 700.

    The capacitor deal makes sense as far as stalling. A Trabant engine will run on one cylinder but only on flat land up to about 30 mph. Any kind of incline will cause it to stall.
  3. 'bant

    'bant Loyal Comrade

    @Caleb It is difficult to say what voltage you should see in absolute terms on the basis of my figures as we are using different voltmeters that have not been calibrated with each other.

    However, the difference in measured voltages between a known bad battery and a new one for my car was between 0.5v and 0.8v in favour of the new battery. Which is significant when you only have 6 volts to start with.
    Last edited: Oct 2, 2015
  4. Caleb

    Caleb Loyal Comrade

    @'bant - I would expect to see a little variation from car to car anyway. Wiring may have aged differently, generators maybe be worn differently so some difference would be expected. Plus like you said unless we were using the same tester it would be hard to speak in absolutes. But it seems to me that the when the lights are on at idle the generator on my car is not making up the difference in voltage used or at least recharging the battery when the lights are off.
  5. Caleb

    Caleb Loyal Comrade

    I hooked up a battery charger over the weekend. Started on Saturday morning and did not disconnect until Sunday morning. When I finally disconnected the charger it was reading about 50% charge. The battery charger I have runs at 6v 6amp. When I disconnected the charger it looked as though it was still pushing between 4.5 to 5 amps. So maybe this means the battery is not taking a full charge?
  6. 'bant

    'bant Loyal Comrade

    The old battery in my car looked old and I know the car had been used infrequently after it was imported to Norway. Infrequent use, with the battery discharging fully, left in a discharged state and then being charged up for the next use is not good for a lead acid battery. My new battery charged up fully within a couple of hours using the "intelligent" charger. I took that as a good enough reason to doubt the old battery.

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