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?

wrote:
does specific-gravity of a conventional lead-acid cell, linearly
measure its AmpHour capacity?

What happen is you double the battery's volume?


If not, what exactly does it indicate with respect to the battery
user's needs?


Try: http://www.universalsolutions.com/te.../RTCPAUFVP.pdf
http://www.faqs.org/docs/electric/DC/DC_11.html

wrote in message
oups.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

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


wrote in message
roups.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.

And you're talking about the specific gravity of just the liquid
electrolyte, of course, not the entire cell.

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.

On 16 Jan 2005 02:08:07 -0600, R. F. Burns R.F. wrote:

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
egroups.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.

Apart from being temperature-dependent, terminal voltage is very dependent on
recent charge/discharge history. Unless a known regime is implemented before
measurement, OCV can be very misleading as a SOC indicator.

On 16 Jan 2005 02:08:07 -0600, R. F. Burns R.F. wrote:

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

AFAIR - no. But internal resistance of battery - yes.

Best,
Borek