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TR5/TR250 Ammeter Question

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glemon

glemon

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Randall's comment in the thread about TR3 alternator conversion got me to thinking about something I always kind of wondered about.

My charging system on the TR250 seems to work fine, correct voltage, battery stays charged. However, the ammeter barely moves, when it does it moves in the right direction but probably no more than 1/8 of the travel on the gauge, even if it hasn't run for some time and the battery is low.

On my 4A it would swing back and forth wildly as load was applied or the engine revved, settling into a slightly charging position on long highway runs. I assumed it was the difference between a generator and control box on the TR4A, vs. the alternator (and control box, but different, on the '68 250 and 68 MGB too I think.)

Anyway, pretty far down on my list of concerns, but curious if you have a TR250 or early 6 with the ammeter (why isn't it an "ampmeter"?) Is mine doing what they normally do?

Thanks, Greg
 
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No particular expertise here but if the battery is fully charged, it won't move much. Try cranking the engine with the ignition disabled. You should see some significant movement.
Tom
 
I have the same with my TR3A converted to alternator and a 60 amp gauge. Very little movement but it does go in the correct direction when I have just started up or if I turn the head lights on with the motor off.
May be because of better control by the alternator regulator and output from the alternator.

David
 
The modern electronic regulators in today's alternators are way better at balancing electrical demand than the crude electromechanical regulators of the 1960s. They work so well that, under normal conditions, you rarely see a net charge or discharge from the battery. Maybe if the battery is nearly flat (like, from keeping the headlights on for a long time without the engine running) you might see a larger initial charge current, but usually you won't see much on the ammeter.
 
So I could probable have stuck with my original 30 amp gauge.

I did the 60 amp gauge and 8 gauge wire to the battery. Overkill?

David
 
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