George White wrote in a message to Roy J. Tellason:

 GM>> Which is a useful indication that the alternator is putting out
 GM>> current -- on most cars, about the only indication.

 RJT> I'm used to vehicles with ammeters...   Most of the old mopar
 RJT> stuff I've been driving for years has had them in there.  Except
 RJT> this last one,  which for some dumb reason has a voltmeter,
 RJT> instead.  Why they started doing that is beyond me

 GW> Cost! :-(. A supressed zero voltmeter is cheap and easy to wire,
 GW> just a wire from somewhere just after the ignition switched point.
 GW> An ammeter has the extra cost (probably more then the cost of the
 GW> meter) of a high capacity shunt in the main feed to/from the
 GW> battery (which means the starter _has_ to have a totally separate
 GW> feed) and two wires from the shunt to the meter itself which have
 GW> to be isolated from the rest of the vehicle wiring.

I knew most of that,  and darned if I can figure why it is I didn't think
of any of it...

 GW> A voltmeter keeps those who know very little happy, but in reality 
 GW> for an auto is more-or-less useless. All it tells you is if the 
 GW> alternator is regulating, not the useful bit of information, how 
 GW> much charge the battery is taking.

I agree,  though I don't think I'd care enough about it to try and retrofit
an ammeter in my vehicle that doesn't have one.  :-)

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