Here is a device that will test your battery:

*http://tinyurl.com/352k4l*
**
It's not portable, but you should use a load around half your battery's CCA
rating, and since I have a diesel and 800 AmpsI needed this larger one.  You
may get by with a smaller one which HF also has a variety of.  It puts your
battery under a known load (inside the box) and following directions, will
let you know what shape your battery is in, in static mode that is.

Alan Felder

On Tue, Jan 26, 2010 at 1:49 PM, 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
>

--
Alan Felder
Austin TX
82 Diesel Westy