Re: [RE-wrenches] To insulate a battery bank

[Allan Sindelar]

Bob, Extruded polystyrene ("blueboard" or "pinkboard", depending on brand) is designed for direct-burial use, and is unaffected by direct and continuous contact with battery acid. It's also strong enough to directly support the weight of the batteries. So it's a useful material to use, if you have need of insulation. I'll use it if an otherwise tempered space for the batteries has a cold slab or dirt floor, in order to inhibit long-term conductive heat loss. Otherwise, I agree with the others here about the lack of benefit of insulation in battery enclosures. Fundamentally, insulation just retards the rate of heat transfer from a warmer space to a cooler one. Batteries don't generate significant heat at times when the heat is most needed, so they will eventually maintain the same average temperature as their immediate environment. If batteries are directly exposed to sunlight through a window, insulation is called for, to prevent the cells directly exposed to the sun's heat from warming more than the shaded cells. When asked, I recommend either putting batteries indoors (with proper sealed enclosure with controlled ventilation to the outdoors) or in a separate insulated, sun-tempered space, such as a power shed, with passive solar glazing and mass storage, but with no auxiliary heat. Of course, what works here in the sunny Southwest wouldn't work as well in your region. Allan Allan Sindelar Allan@positiveenergysolar.com NABCEP Certified Photovoltaic Installer EE98J Journeyman Electrician Positive Energy, Inc. 3201 Calle Marie Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com On 12/10/2010 4:32 AM, bob ellison wrote: With the amount of lead in a battery bank it changes temperature very slowly. Both gaining and losing heat is a very slow process. I have never insulated battery banks, if in a cold area like here we size them larger for the slower reaction time in the winter anyway. Part of the reason being that I would bet that the acid would raise hell with the insulation! We regularly see battery banks that are 40 degrees or so it presents no problem. If the exhaust fan is running in a 70 degree building all it does is draw the warm air over the top of the battery and not really warm them much anyway, in an unheated building it will probably not make much difference. The only way that I would put insulation in an unheated battery box is on the outside of the plywood, away from the acid and gasses. I would also make it removable in the summer.   No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1170 / Virus Database: 426/3305 - Release Date: 12/09/10 _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org

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