Re: Intermittent power drop when headlights are turned on

Posted by BH On 2012/2/5 22:19:15

I don't completely understand these old charging systems, but have found that if I generally just follow the shop manual tests, the problem reveals itself in comparatively short order.

IIRC, we're working on a 1950 Standard Eight, but the 46-50 shop manual is rather scant on electrical service. However, I believe the Cap'n has both the 1950 AEA Tune-Up System Chart with complete vehicle wiring digram (on reverse) and the Serviceman's Training Booklet on Scientific Diagnosis, which covers the "Charging Circuit" (starting p. 12). Though that training book was published in 1951 (featuring the new 24th Series), surely the basics still apply - as the steps are written without regard to AutoLite vs. Delco. (Just be sure to follow the two-column format of each full page - lest ye skip a step.)

If the voltage regulator cutout relay was not functioning at all, I'd expect a discharge reading on the ammeter at all times that the engine was running, rather than intermittently - that is, only under conditions of high demand. In that case, the vehicle would be running off of the battery at all times (in sufficient for on any long trips), and would need to be recharged using an external charger.

While the generator and voltage regulator have both been replaced in this car, the problem continues and seems to be getting worse. Now, it's possible to have a new or rebuilt unit that's defective right out of the box, but there are other factors to consider.

Have the circuits between ALL components in the charging system and their connections been checked for excessive resistance? I'm still suspicious of a ground problem.