Finally fixed my charging issue and voltage drop problem
Thread Starter
Joined: Oct 2002
Posts: 523
Likes: 58
From: Winnipeg, Manitoba, Canada
Finally fixed my charging issue and voltage drop problem I've been struggling with a charging issue for the past 2 years. It started when my last alternator died. Since then I had issues with the voltage dropping a few days or weeks after installing a new alternator. I switched to a truck alternator and it seemed better but not resolved. The voltage would be at 13.7 volts at the battery (13 volts at dash or 13.5 volts on Scangauge II) when I first installed the new alternator and over the next month it would slowly go down to 11.5 volts or lower. This is with measuring the volts at the battery. Battery was a premium Exide glass pack unit.
I upgraded all of the main charging cables and grounds to 0 gauge wires (battery to alternator, battery to fuse box, battery ground to chassis, engine to chassis). This improved the peak voltage (14.5 volts at battery) but I still had the same leak down issue especially when the car got hot.
Finally found the culprits. There were two main issues.
1) As the car got hot, the resistance in the exciter wire would build and it would pull away from the connector. If I held down on the connector with the car running (I have a hoist), the voltage would come back. So I bent the pin so it pushed against the connector properly. This fixed 75% of my issue.
2) I was still seeing a 1 volt drop from the alternator to the battery. 14 volts at the alternator and 13 volts at the battery. Well it turned out my starter wire at the positive post was glowing red hot. The crimp had loosened up over time and the metal threads at the end by the ring terminal were frayed and turning red hot. Re-crimped it...voltage went up.
No more issues.
I upgraded all of the main charging cables and grounds to 0 gauge wires (battery to alternator, battery to fuse box, battery ground to chassis, engine to chassis). This improved the peak voltage (14.5 volts at battery) but I still had the same leak down issue especially when the car got hot.
Finally found the culprits. There were two main issues.
1) As the car got hot, the resistance in the exciter wire would build and it would pull away from the connector. If I held down on the connector with the car running (I have a hoist), the voltage would come back. So I bent the pin so it pushed against the connector properly. This fixed 75% of my issue.
2) I was still seeing a 1 volt drop from the alternator to the battery. 14 volts at the alternator and 13 volts at the battery. Well it turned out my starter wire at the positive post was glowing red hot. The crimp had loosened up over time and the metal threads at the end by the ring terminal were frayed and turning red hot. Re-crimped it...voltage went up.
No more issues.
