[RE-wrenches] Air conditioning for batteries in hightemperature climate

Fri Apr 22 13:33:26 PDT 2011

Re: [RE-wrenches] Air conditioning for batteries in highPartially right, Jim. Except hotter internal temperatures cause the electro-chemical process to be faster, not slower. Only as temperatures decrease below 25C, which may vary with manufacturer, is the process slowed.

Larry
  ----- Original Message ----- 
  From: North Texas Renewable Energy Inc 
  To: RE-wrenches 
  Sent: Friday, April 22, 2011 12:54 PM
  Subject: Re: [RE-wrenches] Air conditioning for batteries in hightemperature climate

  It's the efficiency of the chemical reaction that creates the loss. The electrolyte solution cannot pull out nor put back the same amount of 'energy' in hotter or colder conditions. When temperatures moderate, the chemical reaction returns to its nominal efficiency. The batterys capacity should not be permanently affected unless SOC reaches extreme levels. 
  Or that's how I recall the process explained for cold temps. I assume the same is true for high temps.
  Jim

    -----Original Message-----
    From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org]On Behalf Of Hugh
    Sent: Friday, April 22, 2011 2:13 PM
    To: RE-wrenches
    Subject: Re: [RE-wrenches] Air conditioning for batteries in high temperature climate

    Hi Roy,

    Hi temperatures will hit the battery capacity but will the battery efficiency be that much affected?  If the battery capacity is inadequate then you need to compare the aircon running cost to the cost of buying a 10% larger battery.  Don't you?

    Cheers

    Hugh

      Bob is correct, I do have an off grid client that uses an AC unit to keep the batteries cool.
      Although we're not in a high temp climate, it does get into the 80's and low 90's here
      in the summer.

      By my calculations, he was losing an 'average' of 10% storage capacity during the 5 month
      period from late spring to early fall. In July and August it was closer to 18%, but for calculation
      purposes, 10% is close enough. His bank capacity is 4800AH @ 48 VDC. That's 230,400 watt hours
      and 10% of that rounds out to 23,000 watt hours lost to heat.

      I showed up one day to check something in the power shed and was dismayed to see a window
      AC unit installed there. An interesting customer discussion ensued and I had to admit he was
      correct in his calculations.

      The Energy Star rated AC unit consumes no more than 3,000 watt hours per day, even in the
      highest heat. Essentially, he's 'spending" 3 kilowatt hours to 'buy back' 20 kilowatt hours of
      storage. He got me on that one!

      That reasoning didn't work on the 6 other AC units that appeared on his house the following
      week. But that's another story altogether!
      Roy Butler
      NABCEP Certified Solar PV Installer®
      NYSERDA eligible PV & wind installer
      PA Sunshine Program Approved PV Installer
      Four Winds Renewable Energy, LLC
      8902 Route 46
      Arkport, NY 14807
      607-324-9747

      www.four-winds-energy.com

      Although no trees were killed in the sending of this message,
      a large number of electrons were terribly inconvenienced.

      On 4/22/2011 7:40 AM, bob ellison wrote:

        I believe Roy has a customer with a huge battery bank that air conditioned the battery room. He ran the numbers and the air conditioning actually made sense.

        Bob Ellison

        From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of R Ray Walters
        Sent: Thursday, April 21, 2011 4:50 PM
        To: RE-wrenches
        Subject: Re: [RE-wrenches] Air conditioning for batteies in high temperature climate

        Are you using temperature compensation? It lowers the voltage when its hot.

        Also, have you considered setting the batteries in a below ground vault? I've had good luck with in floor battery boxes.

        Finally, AGMs and L16s just don't last very long anyway. AGMs maybe 3 years, and L16s I've seen die in under 5 years and we get to 15 below zero.

        My suggestion: temp comp, ground vault, HUP or equivalent cycle life.

        R. Walters

        ray at solarray.com

        Solar Engineer

        On Apr 21, 2011, at 1:22 PM, Starlight Solar, Larry Crutcher wrote:

        Hello Battery Wrenches,

        Over the years I have had several battery banks in Baja and Sonora Mexico fail in just 36 to 48 months. These have been L16 or 8D AGM or flooded banks, 24 and 48 volt systems. The charging systems are working properly and programmed to manufacturer recommended set points and discharges are rarely over 30% DoD.  Some batteries are only used on weekends, some are discharged daily.  I believe what is affecting the short life is the high temperature they live in for 5 months each year. Temps. can hit 115 F in vented battery rooms. I have been thinking about a small air conditioner and insulated battery box to keep the battery at no more than 80 F. There are some portable units that draw about 600 watts and the run time would be very little with a highly insulated enclosure. There is ample power to do this on the home I am changing batteries in now. Has anyone done this and gained longer battery life?

        Best Regards,

        Larry Crutcher
        Starlight Solar Power Systems

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