On Thu, 26 Jul 2007 12:55:16 -0500, "KLC Lewis"
wrote:

I don't find anything on
the Smartguage site that says how their meter can do it without a shunt, and
with only two wires connected directly to the battery bank.

It can't of course, it can only guesstimate. If you want to measure
something you need the proper tools. The tool in this case is a
shunt.

On the other hand you can argue that all that is really needed is a
digital voltmeter to approximate state of charge. If your batteries
are reading 12.6 volts under a light to moderate load, they are at
100%. Dropping down to 11.6 volts under the same conditions, they are
at 50% and need to be recharged immediately.