How do you keep your batteries warm

[frackers]

Gales force winds, low temperatures and the batteries don't like the high charge current when they are near 0 degrees (Celcius that is!!) - the voltage floats up very quickly despite the charge level being low so no alternative but to start loading them down before the inverter goes bang - so I've ended up with less in the batteries that I started with :-(

I've got them in the middle of the paddock at the moment, in the open air so anything I do will be an improvement I think. I'm thinking 6x2 timbers as a base on 4x4's in a pallet type construction, 40mm polystyrene under and round the batteries (because I have loads of offcuts from another project) but not sure about the top as I want plenty of air round them so the fumes don't get to the switch/fuse panel and the inverter.

Any hints?

Cheers

[Volvo farmer]

I built a box for mine with a slanted roof, also used polystyrene insulation but then lined it with EPDM pond liner in case of spills. The little white tube in the picture is a vent to the outside. I put a couple small holes low in the front of the box as well. The theory is that the hydrogen migrates to the top of the box and goes outside. I keep my lid closed at all times unless the batteries are running warmer than ambient in the summer or after an equilization charge

[Chuck]

The first step is to get them in some sort of an enclosure, even if it's just a plywood box. Make sure it has drainage holes at the bottom, in case water gets in, and have a vent or two above to vent the Hydrogen. You might want to put the vents on the opposite side from the prevailing wind. I wouldn't put the insulation too close to the batteries, but that's just me. I'd be afraid they'd get too hot. You might want a separate enclosure for the inverter, fuses, etc.

My batteries are in the barn in a separate area. My inverter and chargers are also in the same room. I find that although the temperature varies a lot, it isn't as bad as outside. The biggest thing is to have a charger that takes the temperature into account, as they will increase the voltage in cold and decrease it in heat (relative to 77 deg. F).

[SparWeb]

I went a little bit overboard with my cabinet... but it is really convenient to get at the batteries.  The little cabinet is outside, mounted on cinder blocks, and the floor is 2x8's on edge spaced 12" apart, because the batteries are 2000 pounds total weight.

Having the charge controller in the box is a bit of a no-no.  I took my chances because they are sealed AGM batteries and the box is far far from air tight.  After 2 years absolutely no sign of corrosion on any exposed electronic boards or copper, but I'm keeping an eye on the lead connector bars because they do have a bit of white scale now.

I put the dump load resistors on the inside of the box to give it some heat in the winter.  It can be 10 degrees warmer inside on a windy day than outside.  In the summer they go outside so that they don't cook!

[Ungrounded Lightning Rod]

Batteries give off some heat from the resistive losses when charging or discharging.  So putting them in an insulated box lets them keep themselves warm in the winter (and keeps out the rain and snow).

Pointers:

 - Adjustable vents so you can switch between a little venting to lose-the-hydrogen / lose-a-bit-of-condensation / but-stay-warm in the winter and a lot of venting to vent-for-cooling / lose-lots-of-condensation in the summer.

 - You also want to raise the batteries off the floor a tad and let air circulate around and under them so they are about the same temperature top-to-bottom and from one cell to another.

[Photowhit]

My batteries live outside, under/behind the solar panels.

The battery box is on one side of a common wall with the power center and inverter on the other side like a 'dP' with the a common long stroke.

The battery box side is built big enough to house a forklift battery or 8 L-16's or 12 golf cart batteries. Just 4 golf cart batteries right now. The Power center side is cantilevered out standing a bit over 7 feet tall down to about 3 feet, about 16" deep.

I do place some 2" blue board insulation around the batteries in Winter months, the charging does warm the batteries. I use flooded lead acid as best bang for the buck.

Having the inverter and power center on the other side of a sheet of plywood makes running wires and so much easier. Having the battery box/PC and inverter at the panels make wire runs short other than the higher voltage AC making for smaller gauge wires.

I use a Prosine inverter which is designed to handle the high temp and semi outdoor nature of the set up better than some inverters, They are often used on boats.

It regularly gets to -20c here in Missouri, I have yet to freeze a battery. I can't recall and am too lazy to search, but they do loss capacity as they get colder maybe 10% at 0c 30% at -20c (pulled these figure out of thin air, just my weak memory)