specific gravity of the electrolyte at a particular temperature will give
you what you seek
wont work for sealed batteries though

On Tue, Jan 26, 2010 at 11:49 AM, Don Hanson <dhanson928@gmail.com> wrote:

>  Is there a way to tell about the auxilliary battery condition in a VW (or
> any rig, for that matter)?  I've been working with all kinds of batteries
> over the years and I always have been puzzled about how to find out what I
> might expect from the battery.  I have a digital multimeter and I get
> voltage readings but I'm told that is no real indicator of how good the
> battery is charged or is capabale of being charged...
>  Is there an instrument that I could wire into my systems (I have a few
> different vehicles with multiple battery systems) where I might get an
> actual meaningful readout that would tell me..."Hey, don't expect much more
> from this battery till you charge it more" or "this battery is shot" or
> "all
> your batteries are in fine shape with 100% charge"?
>  I have seen battery condition indicator gauges in yachts..I've seen
> voltage indicators on some rigs.  My travel trailer has an LED readout and
> for that matter, so does my semi-westie van...but those things seem pretty
> much a joke...
>   What should I wire into my systems to give me a better handle on how much
> juice I have in the batteries?  Is there anything that works..or do I just
> have to keep guesstimating as I have been doing all these years?
>  Thanks, Don Hanson
>