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Voltage question

posted by  someone claiming to be n0v8or on  Wed Nov 20 02:20 CST 2002 [RELATED]

A fully charged battery should read closer to 12.8V. Perhaps your meter is inaccurate. Modern alternators have an internal voltage regulator that sets the charge voltage according to temperature. Typical values are:
at 20C . . . 14.6V
at 0C . . . 15.1V
at 40C . . . 14.1V
For most cars, this is alternator case temperature, not the actual battery temperature. Only a few cars have battery temperature sensors.

Low charging voltage and poor regulation (voltage drops with a load) could be caused by 1 or more open rectifier diodes in the alternator. An oscilloscope will confirm this (look for missing cycles in the ripple waveform with the engine running).





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New Voltage question [S70][1998]
posted by  DG  on Tue Nov 19 14:02 CST 2002 >


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