On Tue, 11 Jan 2005 10:22:51 +0800, budgie wrote:

On Tue, 11 Jan 2005 00:35:58 GMT, "NSM" wrote:


wrote in message
groups.com...
| does specific-gravity of a conventional lead-acid cell, linearly
| measure its AmpHour capacity?
|
| If not, what exactly does it indicate with respect to the battery
| user's needs?

It's proportional to % of charge. I doubt it is linear. See
http://www.buchanan1.net/lead_acid.shtml

It is close enough to linear that some battery manufacturers provide
coefficients and/or graphs of SOC vs SG and temp.

It does of course require "calibration" to accomodate the actual acid/water
proportions at fill and any loss/replacement.



Battery terminal voltage is also an indication of specific gravity and
SOC.

R.F.