L-16 "cycling" requirements? [RE-wrenches]

[Geoff Greenfield]

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Good discussion... I probably need to turn up my charging set points a few
notches.  On many systems I have used "out of the box" settings... 14.4
bulk.  Higher would mean more watering, more heat stress on batts? but also
more effective use of potential storage and (probably) more shaking off of
sulfation crystals...

So - a customer asked me my opinion on some advice he got re: batts (Flooded
lead acid - in this case 2 volt 883AH KS-17s) "should I discharge them on
purpose, to cycle them, to make them last longer?"  My response was
something like "well - in a forklift or scrubber application the batteries
are considered expendable and the grid based charging free, so choices and
practices are different.  My approach and my understanding of the off-grid
approach is to "baby" them, always conserving, watching voltage and staying
in the top end as much as you can.  Shoot for achieving full charge at least
once a week, and equalize/water 3-4 times per year."

Am I missing something?  Am I doing my batts and my customer's a disservice
with this approach?  Almost all of my systems have at least c/20 capacity
off the PV, often more. I shoot for 3 days of zero input autonomy, and
design around 50% D.O.D.  Most systems have undersized portable AC gennys
that are more to "help" the system in winter with big loads and charging,
but also can help some systems get started on a full charge or equalization
cycle.


For a brighter energy future,

Geoff Greenfield
NABCEP Certified Energy Practitioner

THIRD SUN SOLAR & WIND POWER Ltd.
340 West State Street
Athens, OH 45701

www.third-sun.com
(740) 597-3111
Date: Thu, 19 May 2005 17:57:27 -0700
From: "Doug Pratt" <dmpratt at sbcglobal.net>
Subject: RE: L-16 charging voltages [RE-wrenches]



A better question is why did someone install wet-cell L-16s on an emergency
back up system? They're going to suffer a short, ugly life no matter what
you do! Wet-cell batteries need exercise to stay healthy...they aren't going
to get it. They also need regular watering...experience leads me to predict
they won't get that either. Wet-cells and backup systems are an unwise
combination. (Yeah, I've done it too, but that was years ago. Now I know
better!)

Cheers,
Doug Pratt


Dave,

What you say makes good sense to me... and I have found similar results with
the
systems I do and maintain. I have also read contradictory advice on this
list
that L-16's being floated (for batter back up grid intertied systems) need
to be
EQ'd once a month to "stir" the electrolyte, yet if they are being floated
should there be a small electrolyte circulation happening anyway so why the
EQ?

Todd

For a brighter energy future,

Geoff Greenfield
NABCEP Certified Energy Practitioner

THIRD SUN SOLAR & WIND POWER Ltd.
340 West State Street
Athens, OH 45701

www.third-sun.com
(740) 597-3111

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