Cooling the batteries

13»

Comments

  • WaterWheelWaterWheel Posts: 282Registered Users ✭✭✭
    edited September 10 #62
    Adding ice means more than just $2 a day.      it means the time and fuel stopping every day during the warmer months to purchase and add the ice.

    The largest roadblock to using a water bath (chilled, iced, or just water out of the hose) is building a water tight box which can be easily filled and drained that also has a vent fan, screened air intake holes, and a lid.     The box needs to withstand water pressure pushing out on the sides for 10+ years, have a liner than can resist 35% sulfuric acid (EDM is best but PVC should last over 10 years in light acid) and a drain that can also withstand being in a low concentration of acid for 10+ years. 

    If there is a problem with the drain or liner that box full of batteries is too heavy to move so it needs to be built right the 1st time.       In my case I do worry about the $20 pump holding up since I don't know what plastic it is made of or how the vinyl insulated cord will hold up but the tiny bit of acid diluted in 70 gallons of water shouldn't be a problem.     The water lines are also heavy vinyl.       

    Conext XW6848 with PDP, SCP, 80/600 controller, 60/150 controller and Conext battery monitor

    21 SW280 panels on Schletter ground mount

    48v Rolls 6CS 27P

  • jonrjonr Posts: 1,074Solar Expert ✭✭✭✭
    edited September 10 #63
    I wonder if one could purchase a plastic water utility or holding tank and cut the top off of it.
  • Dave AngeliniDave Angelini Posts: 4,010Solar Expert ✭✭✭✭
    Still far less to worry about than a boat on the ocean :)

    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • littleharbor2littleharbor2 Posts: 1,027Solar Expert ✭✭✭✭
    Pretty, Van Gogh'esk  graphic.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • softdownsoftdown Posts: 1,889Solar Expert ✭✭✭✭
    Adding ice means more than just $2 a day.      it means the time and fuel stopping every day during the warmer months to purchase and add the ice.

    The largest roadblock to using a water bath (chilled, iced, or just water out of the hose) is building a water tight box which can be easily filled and drained that also has a vent fan, screened air intake holes, and a lid.     The box needs to withstand water pressure pushing out on the sides for 10+ years, have a liner than can resist 35% sulfuric acid (EDM is best but PVC should last over 10 years in light acid) and a drain that can also withstand being in a low concentration of acid for 10+ years. 

    If there is a problem with the drain or liner that box full of batteries is too heavy to move so it needs to be built right the 1st time.       In my case I do worry about the $20 pump holding up since I don't know what plastic it is made of or how the vinyl insulated cord will hold up but the tiny bit of acid diluted in 70 gallons of water shouldn't be a problem.     The water lines are also heavy vinyl.       

    I was merely suggesting to try it once, if convenient, and see what results are obtained. . 

    An idea (for future applications) on a battery box - an old chest freezer offers pretty good insulation and robust construction.

    Water pumps normally last several years if the manufacturer is good. I've used hundreds. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • jonrjonr Posts: 1,074Solar Expert ✭✭✭✭
    Once you know how much ice/day is needed, then you can calculate the exact size chiller needed (for similar conditions).
  • WaterWheelWaterWheel Posts: 282Registered Users ✭✭✭
    edited September 11 #68
    I'm now firmly of the opinion that a 1/6hp chiller would have been sufficient.      The current 1/4hp chiller draws 320 watts, a 1/6hp chiller draws about 230 watts.  

    The 1/4hp chiller is easily keeping the batteries around 75 degrees running 4 hours a day and if left running 8-10 hours would cool the batteries into the high 60's.
    2700 lbs of batteries sitting in 570 lbs of water.      3/4" plywood box with no insulation except 1.5" thick layer of 2x4s under the box (raised to make space for floor drain)  with air gaps between them... see picture post #35.
    Box lid left open but will be closed during the winter.

    Conext XW6848 with PDP, SCP, 80/600 controller, 60/150 controller and Conext battery monitor

    21 SW280 panels on Schletter ground mount

    48v Rolls 6CS 27P

  • WaterWheelWaterWheel Posts: 282Registered Users ✭✭✭
    edited September 11 #69
    I was curious if the cooler water temperature was making the battery temperature sensor read low.      The sensor is attached to an inner battery cell wall with an air gap between it and the outer plastic battery shell and is below the water level.

    The battery sensor currently reads 74 degrees.      I used the temperature probe that came with a multi-meter and dipped it into the electrolyte in 4 cells.       All 4 cells are 73 degrees so the chilled water is not throwing off the battery sensor reading. 

    Cloudy morning so the batteries are just now nearing the end of absorb,    Air temperature is 87, water is 66, batteries are 74.      

    Conext XW6848 with PDP, SCP, 80/600 controller, 60/150 controller and Conext battery monitor

    21 SW280 panels on Schletter ground mount

    48v Rolls 6CS 27P

  • softdownsoftdown Posts: 1,889Solar Expert ✭✭✭✭
    Guess the battery temp might be in the 90's without the cooling apparatus. Seems pretty successful so far.

    There are dozens of variables that could be experimented with if so inclined. Impact of insulation etc. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • WaterWheelWaterWheel Posts: 282Registered Users ✭✭✭
    edited September 14 #71
    Update day 11

    Batteries have been in the same water the last 11 days with chiller running 4-6 hrs a day depending on how cloudy it's been.     Hot day today for the middle of September.

    12pm   air 91, battery 77, water 75, chiller just turned on
    3pm     air 95, battery 75, water 68, absorb ended about 2:30
    5pm     air 96, battery 73, water 64
    6pm     air 94, battery 73, water 63 chiller just turned off

    Without the chiller I'd expect to see the batteries over 100 degrees today.      As someone mentioned earlier in this thread preventing the batteries from gaining more heat than they can lose overnight is important.        Before the chilled water bath after a long spell of warm weather (over a week) I sometimes saw the batteries running 10-12 degrees warmer than the air temperature hours after absorb has ended and sometimes still above 90 degrees the next morning if we've had a week of 90+ degree days (74-80 degree nights).     So every day the batteries get a little hotter daily as the air temperatures stay roughly the same day after day until the batteries are staying 10+ degrees warmer than the air even at 5am.

    If using ice for cooling I could possibly see the need for insulation but the results with the chiller are fine without insulation, and the chiller is only using excess power during absorb and float.

    Conext XW6848 with PDP, SCP, 80/600 controller, 60/150 controller and Conext battery monitor

    21 SW280 panels on Schletter ground mount

    48v Rolls 6CS 27P

  • Thick8Thick8 Posts: 47Registered Users ✭✭
    I use a closed loop geothermal cooler for my PCs. I didn’t do a field installation but water bored a 35’ hole and dropped a homemade heat exchanger into it. Transferring about 1000 watts into the ground with a 12 volt 13 watt Swiftech PC pump. System water temp never gets above 78F. Will probably do something similar for my batteries.
  • Thick8Thick8 Posts: 47Registered Users ✭✭
    With both computers idling or light load (about 300 watts) the water temp is 72F. The ground water temperature is 69F year round so it could cool batteries in the summer and heat them in the winter.
  • Marc KurthMarc Kurth Posts: 446Solar Expert ✭✭✭✭
    PV is still cheap and long lasting compared to batteries. When PV got really cheap, design approaches started shifting:
    Design a system for very low average daily DOD.
    Add enough PV to support some mechanical cooling for batteries and electronics in hot climates
    Get a solid 12-15 years from the battery bank.

    I always have more questions than answers. That's the nature of life.
13»
Sign In or Register to comment.