[RE-wrenches] Battery Experience

[Jason Lerner]

Hi Larry,

I am not talking about doing a discharge to 90% DOD,  I was talking about doing a discharge to 20% DOD.  Let's say summer folk come up for 1 month a year,  and discharge to 20% DOD daily,   then fully recharge with a 2 hour absorb charge and then float until the sun goes down. This systems charge controller is set to auto EQ every 30 days to stir up the electrolyte,  and all loads are turned off when nobody is there.  Let's say there is 4 FLA golf cart batteries and 500 watts of PV.  Four average sun hours a day.  How long would you expect these batteries to last?

Thanks very much,

Jason

Waldron Power and Light Co.
On Jul 13, 2012, at 9:18 AM, <larry at starlightsolar.com> <larry at starlightsolar.com> wrote:

> Jason,
> 
> Forcing a lead acid battery to deeply discharge does not increase capacity or life of the battery. It only shortens battery life and may damage the battery. This is one of many battery myths. 
> 
> Larry Crutcher
> Starlight Solar Power Systems
> -------- Original Message --------
> Subject: Re: [RE-wrenches] Battery Experience
> From: Jason Lerner <wapalco at rockisland.com>
> Date: Fri, July 13, 2012 7:28 am
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
> 
> Hello John,
> 
> This time of year I service off grid summer cabins where people come up once a year for a few weeks.  The batteries in these systems generally do not die from over cycling,  but from over/under watering,  acid stratification, corrosion,  and generally being ignored.  The more savvy customers I will recommend they turn off the PV's when they are there to get a deep discharge in.
> 
> Could you recommend any thing else they could do to lengthen their battery bank lifespan? These systems generally have a small PV charging capability,  and float charge 350 days a year. It seems ironic that these systems that really never get used,  and my battery bank at home that gets used (but not abused) and cycled daily, will last the same number of years.
> 
> Thanks very much,
> 
> Jason Lerner
> 
> Waldron Power and Light Co.
> 
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