Cold Weather Around the Corner

Philip C
Philip C Solar Expert Posts: 45 ✭
in Off Grid Solar & Battery Systems #1
In preparation for the winter months I would like to see how most keep their batteries performing in cold weather.
Do you keep a slight load on your batteries at night? Has anyone placed Christmas lights in their battery box?
My biggest concerns are loads first thing in the morning.

Thanks
Philip
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Cold Weather Around the Corner

    What do you mean "around the corner"? It's been below freezing very night for the past three days here!

    It gets wretchedly cold inside the cabin at night because the place leaks like a sieve and has no insulation (it's on my "To Do List", okay? Has been for 15 years). Yes, the cooler temps reduce battery capacity. Build enough in to begin with and there's no problem. People who run on the edge fall over it.

    Batteries do not freeze if they are charged. When we leave here for the Winter I disconnect the inverter and leave the panels & controller running. The batteries sit inside a box with 2" of foam around the sides and 3" on top. No worries.

    Christmas lights here wouldn't do any good: they're LED. :D Besides which, the running of enough light to provide heat would draw the batteries down more.
    When you start to pull current in the morning (mine run a refrigerator all night) that will increase the battery temperature and their capacity will actually go up a tiny bit as they warm.

    Which reminds me: battery monitors ought to have remote temperature sensors too. Anyone know of one that does?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #3
    Re: Cold Weather Around the Corner

    Do you have an insulated battery box (or in a basement/heated living space)? Then you should be OK if you are using the batteries "normally" (cycling them).

    If the batteries are purely for standby (emergency backup power), and not in a conditioned space, then if the batteries drop below ~40F (~5C), their capacity drops significantly. But--if you have an emergency and begin cycling (batteries tend to heat most when recharging ~80-90% state of charge), you should be OK.

    If you have an insulated box and perhaps some battery heaters (running from AC mains--I would suggest a thermostat--control box outside the battery enclosure to avoid hydrogen gases and electrolyte fumes) would help (at the cost of heating load).

    Otherwise, if this were a cabin that is cold soaking in the snow (and not being used), just fully recharging the batteries before you go and installing a 1% rate of charge solar panel on the wall of the cabin (vertical, above snow), would keep the batteries well charged and out of the danger of freezing.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #4
    Re: Cold Weather Around the Corner

    What are you're winter temperatures? Here in Nova Scotia I used to wrap my L-16's in insulation for the cold months, but then one Winter I didn't seem to get around to it and found there was very little difference in my case. Insulated, their temperature hung near zero C during the coldest part of the season, while if left uninsulated, they dropped to perhaps minus 5 C. Not a huge difference, but still a difference, so the last couple of years I didn't bother insulating. This year I might.
    The act of being charged during sunny days would bring their temperature up and they would be slow to loose that heat overnight, especially if insulated. BTW, insulated ot not, my batteries are in a box, which I suppose would help to some extent at keeping the batteries warm.
    Of greater importance in my location is repositioning my panels to the vertical for Winter. This both prevents ANY snow buildup and takes advantage of sunlight reflected off snow covered ground, giving me the highest output of any other time of year. (as long as the sun is shining of course):D
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #5
    Re: Cold Weather Around the Corner

    What exactly are trying to achieve? As has been stated, charged batteries won't freeze at least till -40.

    Christmas light in the battery box? How festive!

    Tony
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  • Crotalus
    Crotalus Solar Expert Posts: 26 ✭
    #6
    Re: Cold Weather Around the Corner
    Cariboocoot wrote: »
    Which reminds me: battery monitors ought to have remote temperature sensors too. Anyone know of one that does?
    This one has it as a extra cost option. http://www.xantrex.com/power-products/power-accessories/linkpro-battery-monitor.aspx I was looking for a battery monitor for my small travel trailer. The problem I had with it was it would monitor two batteries banks. I have one Trojan 27TMH group 27 battery rated at 115Ah @ 20 Hrs. The extra cost for the second battery to me was not cost justified. The Link-Lite does not have the option of a temperature probe. I ended up with this one that does not have a temperature probe but has one battery bank monitor as was very easy to install. http://www.victronenergy.com/battery-monitors/bmv-600s%20and%20bmv-602s/ I got the BVM-600S and so far I am happy. The boating community has a lot of neat things that can be used in small fiberglass trailers. They are like a boat on wheels.

    Keith
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #7
    Re: Cold Weather Around the Corner

    philip,
    as was said, a tad of insulation can keep them warmer, but don't choke the batteries of air. big loads first thing in the morning can be of a concern as the capacity is slightly lessened due to that cold. all you can do is up-size the batteries taking into account the cold derating if it proves to not perform well enough on those cold mornings. it may be good to hold off on large loads until later if you can and having light loads on will tend to warm the batteries a bit, but i would not advise doing this overnight as you could lose too much capacity. also, starting the loads not until after the sun has started throwing a charge to the batteries can help quite a bit. you not only have the charge warming the batteries, but you get the side benefit of the loads to the batteries being offset by the early morning production when you start them.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #8
    Re: Cold Weather Around the Corner
    Cariboocoot wrote: »

    Which reminds me: battery monitors ought to have remote temperature sensors too. Anyone know of one that does?

    Not exactly a battery monitor, but the remote display for my TS-MPPT-60 shows battery voltage and temperature.
    Right now @ 7:03 PM and almost dark, Battery voltage is 13.1, Battery temp: 18C.
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #9
    Re: Cold Weather Around the Corner

    Our utility room that contains the battery bank, inverters, and all the other equipment, is on the north side of the house. It is insulated but it is not heated. However, it's very rare that it gets below freezing in there, just from the heat given off by the inverters and controllers, and the fact that one wall is a house wall. The battery bank is in wooden cases that are insulated with foam, and they are up against the house wall. I keep the bank at 60 degrees in the winter time with a little duct fan that draws warm air from the kitchen and blows it into the battery cases. The duct fan is turned on and off by a Suncourt DuctStat to maintain the desired temperature in the battery cases. The duct fan is very quiet and we can't hear it running in the kitchen. The duct fan is 120 VAC and it draws about 15 or 20 watts. It has worked pretty good for us.
    --
    Chris
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