Electrical Overcharging

[patrickt]

Originally Posted by DougD

A voltmeter reads VOLTS, an ammeter reads AMPS.

The ammeter reading will vary by the load imposed on the circuit. Were your fans running? Headlights on? Anything else that cycles on/off or operates intermittently?

Assuming his car is wired normally, the ammeter will sit between the battery and the entire system's load and alternator. Increasing or decreasing the load should not affect the current running through the ammeter if the alternator/VR are performing properly -- and certainly will not make the ammeter point over in the plus direction. He really ought to buy that inductive ammeter of mine that I show in my previous post. It's a hundred bucks well spent. It sounds like he might just have a misbehaving gauge, and seeing a "normal" volt reading doesn't really tell you too much about current flow. Putting an inductive gauge on the wire would tell him for sure. Not to mention how cool it is to capture the intitial draw of heavy items, like fan motors, when they come on. MSD boxes usually have their feed sit on the "battery" side of the ammeter, though -- and they make a big deal about that in their instructions. Big stereos sometimes sit there too. But it boils down to either his gauge is broken, or the current is going somewhere over to the battery side of the ammeter's circuitry.