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Old 09-09-19, 05:48
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Tony Smith Tony Smith is offline
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Join Date: Feb 2003
Location: Lithgow, NSW, Australia
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Cab 11 used a brown faced "Batt" meter. While not a true Voltmeter, they read approximate battery voltages from 5V to 9V. These voltages are not marked on the gauge, only bands of red, orange and green to indicate safe levels. Lower red band was up to 6.2v, orange from 6.2v to 7.1v, green was 7.1v to 8.25v, upper red was above 8.25v.

Ford only used these from '40 to '41. Cab 12 changed to a brown faced Amp meter, Cab 13 had a grey faced Amp meter.

The Batt meter can be modified to work on a 12V system and show the correct bands of voltage ranges from 10V to 14V. You cannot use a regular voltage converter for other gauges, as these will just output a constant 6.8v and will peg the needle in the orange band irrespective of the electrical system's condition (until your 12V battery drops below 6.8V!) Note that the Batt meter is polarity sensitive, some vehicles are Pos earth, some are Neg earth.

The Amp meter is an induction coil with a wire simply passing trough loop on the back of the gauge. This will work unmodified on a 12V system, but only in a -40A to +40A range. This is fine for a Generator system, but most Alternators will exceed this range.
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