[VAC] Re: Batteries and Converters

["Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxx>]

Any meter that's temperature sensitive isn't quite state of the art. The
digital have far better resolution to small changes and tend to be
better calibrated than analog meters.

Unless there is a problem with an open cell, lead acid terminal voltages
should track with specific gravity as indications of charge. This is not
true of other battery chemistry but is a fundamental characteristic of
lead/acid batteries.

So long as the battery is capable of supplying a load, the voltage
should be an accurate indication of charge. Its important to test a
battery occasionally with a significant load to check for losses of
plates and active materials. It takes very little current to supply a
volt meter and there need be little left to run the volt meter.

The control panel display is strictly a crude voltage indication. 

The meters that read both voltage and current and compute watt hours in
and watt hours out like Jim Dunmyer's eMeter do keep better track of a
battery condition, but cost far more than a volt meter.

Gerald J.