Cycling of new batteries [RE-wrenches]

[Steve Willey, Backwoods Solar]

I have experienced that a too deep cycle early in the life of Trojan L-16
results in the following:
Recharge to full voltage 2.5+ per cell even, and furious gassing, but the
hydrometer shows only 1200 to 1220.  Simply will not go higher.

I spoke with an engineer at Trojan who insisted if the voltage and gassing
were up, the battery was fully recharged. Well, where was the sulfur
material if not in solution I wondered? He assured me it would straighten
out after a bunch more normal cycles. This it did. I have seen at least 3,
maybe 4 instances of this exact behavior., one in my own camper in storage
with inverter foolishly left on. Anyone else?
Steve Willey,
Backwoods Solar Electric Systems
steve at backwoodssolar.com


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Date: Wed, 26 Nov 2003 11:08:59 -0700
From: "Windy Dankoff" <windy at dankoffsolar.com>
Subject: Re: Battery Life in Grid-Tie Systems [RE-wrenches]
Kurt,
Clive said:
>... Plates have to expand to
>get the chemical reaction to start.
>Cell performance improved after several deep cycles.

I just spoke with Surrette Battery Co. They confirm the need for deep
cycling before the battery will perform to full capacity. They say to
expect 70% on the first cycle, increasing to 90% after about 10
cycles, and about 30-40 cycles to gradually reach 100%.

My experience with RV and golf-cart batteries has been that the first
cycle appears to yield only about 50% capacity, and then it improves
gradually with cycling. I tell customers that it's like stretching
out a new balloon before it will blow up to full size. My advice for
off-grid has been to make a deliberate attempt to perform one deep
cycle initially (after topping off), and then let nature take its
course after that. That seems to do the job from what I've observed.

For backup service however, more deliberate cycling may be advisable.

This is an immediately measurable factor -- therefore, battery
manufacturers should be able to advise for their specific batteries.
I suspect that batteries that are specifically designed for backup
service may have less break-in requirement.

Windy


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