Battery Life in Grid-Tie Systems [RE-wrenches]

Clive Wilkins, PowerSense powersense at horizon.co.fk
Fri Nov 21 01:39:03 PST 2003


Hi Bruce,
Three things  that cause the pos. plate to bulge: overcharging, too long on
float duty ( batteries on float duty should have a periodic discharge test
to check that they do in fact have the capacity to do the job they are there
for ) Equilise charge too often..
The pos. plate always corrodes first. To counteract this inhibitors are
included  in the mix. and   pos. plates is cast under high pressure to make
it more dense than the neg.
The Plante type cells had  pure lead plates with no inhibitors, but they
were design for float duty.
 Cheers Clive




----- Original Message -----
From: "Bruce Geddes" <b.geddes at clear.net.nz>
To: <RE-wrenches at topica.com>
Sent: Thursday, November 20, 2003 8:08 PM
Subject: Re: Battery Life in Grid-Tie Systems [RE-wrenches]


> Hi Scott,
>              This preocupation with cells being on the negative or
positive
> end of a battery fascinates me.  The current MUST go through all cells in
> the string so it (electrically) makes no difference where they are.  There
> may be some environmental difference but this should be taken care of by
> good installation.
>
> Also I find the comments from the Trojan rep interesting.  Cycling a
battery
> to any depth causes stress which ages the battery mechanically.  The
deeper
> the cycle, the more the stress, the shorter the life.  As pointed out
> earlier in posts the only reason to work the battery is to prevent
> stratification and inter cell variance.
>
> Batteries such as L16's are not made to last forever.  They are a
compromise
> between cost, performance and life.  I regularly replace L16's, T105's etc
> after 3 to 5 years use.  Hence my love of traction cells which have proven
> to last more than twice as long despite severe abuse but at less than
twice
> the price.  You gets what you pays for.  Mind you, on a hydro based system
I
> would have expected a little longer than you got.
>
> It all comes down to what the battery is built for.  The longest lasting
> batteries (lead acid) are the standby batteries with pure lead grids such
as
> the old Faurex.  I have seen these still working after 20 years.  Problem
is
> try to cycle them and they will break up.
>
> If anyone has a good, technical explaination to justify the beliefs about
> +ve or -ve ends of batteries failng I would really like to hear it.
>
> Bruce Geddes
> PowerOn
>
>
> > Last weekend, one cell in the battery which is now my main (-), not the
> one
> > using extra water, died. It would not respond to any charging input from
> the
> > hydro nor a backup generator while the other two cells in this battery
> > quickly attained a 1275 + hydrometer reading as did the other batteries
in
> > the bank. I spoke with a Trojan engineer at great length about this
> > situation and after a careful review of my entire system's parameters,
he
> > concluded that I did not cycle my batteries deep enough.
> >
> > In summary, he said:
> >
> > Minimum 20% - 30% discharge on a regular basis;
> > Equalize once a year if hydrometer readings don't indicate to do it more
> > often;
> > The main (-) battery will use more water; and
> > Rotate battery positions once a year.
> >
> >
> > So do I believe him?? and does anyone have other comments on my battery
> > situation?
> >
> > Thanks
> >
> > Scott
> >
>
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