Re: 1932 903 battery not charging

Posted by Owen_Dyneto On 2014/3/16 8:13:04

Of course you should get a small discharge on just turning on the ignition key, that reflects the current draw of the coil - should be about 3 amps or so. More than that indicates something abnormal, perhaps a short in something that's wired to the ignition switch (heater blower, radio, etc.).

A 10 amp charging rate with the VR755 is normal if you have the 3rd brush adjustment at a minimum - turn up the 3rd brush for a higher charging rate and recheck. You should get 20 amps or close to it at normal road speeds.

Does the ammeter show "zero" with the battery connected but the key and all accessories off?

The battery is charging if the ammeter hasn't been damaged and shows positive at engine speeds higher than an idle. The voltage at the battery should also rise from about 6.6 to about 7.2 or thereabouts. If you doubt the voltmeter readings put the car in a darkened garage, engine idling and headlights on. Then increase the engine speed to a fast idle and the lights should get noticeably brighter.

When is the last time you pulled the band cover and looked at the brushes and commutator? Commutator should be bright copper. All 3 brushes should have some reasonable length remaining and under spring tension against the commutator. Is the commutator oily from excessive oiling of the rear bearing?

Does the battery hold a charge? Charge it with your charger to an electrolyte specific gravity of about 1.275 and let it sit disconnected overnight, and check again 24 hours later. If it's lost the charge you probably have a bad battery, perhaps an internal short. A quick and sometimes meaningful test - to all 3 cells bubble hydrogen gas when on your battery charger?