Hi Stuart,
The ammeter on my TC just bounces around all the time the engine
is running. Turning on the headlights shows an appropriate discharge
on the meter, so I assume it's working ok.
>To prove further that the meter is probably okay, I removed it from the
>TD and put a 12 vdc 10 amp battery charge across it. A good healthy
>switch in the correct direction. I switched charger leads and the needle
>swung in the opposite direction. Doesn't this indicate the meter is okay?
I doubt this setup would do damage to your ammeter. The ammeter's
internal resistance is very low (to minimize the voltage drop through the
meter itself), so at 10 amps its internal power dissipation (i.e. heating)
should also be very low. The same cannot be said for your battery charger,
however.
A better way to bench test an ammeter would be to wire the battery charger,
the ammeter, and a headlight in series (e.g. +lead from battery charger
to one lead of ammeter, other lead of ammeter to one headlight terminal,
other headlight terminal to -lead of battery charger). A headlight will
usually draw three amps or so. You can reverse the ammeter connections
to test the other direction of current flow. You could also wire more
headlights
in parallel to the first to increase the current flow.
I hope this helps.
Rich
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