From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Chassis Battery Charging
Date: Mon, 25 Aug 2008 12:20:36 -0400
Message-ID: <q4m5b4p60p12dphfq313cq62pmi5kf44hs@4ax.com>

On Mon, 25 Aug 2008 08:05:14 -0700, Vince Wirth <vince@Iknow.net> wrote:

>On Mon, 25 Aug 2008 02:18:44 -0500, JD <ham@123.net> wrote:
>
>> The fully charged reading is 12.6
>>+/-.
>>
>>Nit Picky, I know but misleading info can cause problems for the
>>unknowing.  I had responsibility for lab calibrations in a Hi-Rel
>>semiconductor facility at one time.
>
>If the fully charged battery is 12.6 then why do you add the +/- ??

Blind hog finding an acorn?

>Really Nit picking or something else.  I doubt that most people here
>have a meter - other than Neon - that can read down to the Millivolt
>range. I had the responsibility for assembling, testing and launching
>Spacecraft at one tine.

For a couple of years now I've been accumulating battery data sheets and
engineering manuals from battery companies.  It's taking that long because
some company seem to not want their users to know how to actually use their
products properly.  I've done all of this with the intention of publishing the
net's most comprehensive go-to place for battery information.  One of those
round tuit projects.

What this is leading into is this.  Once one has looked at a few dozen battery
spec sheets, he quickly learns that there IS NO blanket set of standard
voltages.  Batteries of slightly different chemistry, even from the same
manufacturer and family type, have slightly different voltages.  I've not been
able to discern any pattern to the mess.  The ONLY thing that one can do if he
is interested in extended battery life is get the manufacturer's data sheet on
the particular battery he is dealing with.

The difference in voltages is small and they don't matter in day to day use
but they are important if one needs decade(s) of life instead of years.
Off-grid folks, for instance.  EV'ers for another instance.

With my RV, traditionally I've not cared much, as 2-4 years of life was good
enough.  Now that I have 5 fairly expensive batteries in my rig and am about
to add 1 or 3 more in anticipation of my battery powered AC, suddenly I need
to care because replacing the pack now involves serious money.

Ergo, I've trimmed the resistors that form the simple D/A converter inside the
Charge Wizard to produce exactly what my battery manufacturer specifies in
terms of peak absorption, float and equalization voltages.  How much
difference it makes is yet to be determined.  The off-grid guys say it makes a
hell of a difference.  We'll see.

John