Ammeter on a buddy's car reads fine when you start the car. Rev the engine and the needle swings back and forth between charge and discharge rapidly. 12 volt system, points, condenser, inline Ford 4. Any ideas? Thanks as always, js
Really not enought info. Gen or alt?? Alt internal external volt reg? First guess loose conection/broken wire somewhere in the charging system.
Thanks for the responses. Been waiting for a return call from the owner to verify, but I am reasonably certain it is an alternator with an external regulator. Regulator was my first guess. We used to just take them apart and clean the contacts, but only after smacking it with the handle of a big screw driver to "unstick" it. I don't recall a gauge ever acting this way, but I guess if the circuit is just opening and then just closing, it would cause this fluctuation from charge to discharge. If it is an internal regulator, I presume he should just have it rebuilt or get a new one. Thanks. js
If alternator has v belt the first thing I would check is condition of belt and pulley, and if it is tensioned correctly. If that don't help then go from there on the other suggestions.
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