[RE-wrenches] To insulate a battery bank

[Nick Soleil]

Hello Wrenches:
    I have always insulated my battery boxes (or the battery room).   I have 
built hundreds of battery boxes, and insulated them all with 1-1/2" rigid foam.  
I have never seen the foam deteriorate, with 15+ years experience on many 
sites.  As you know, the capacity of the batteries is much lower when the 
batteries get cold, so adding insulation will certainly improve the performance 
of the battery.
    Unfortunately, I have seen thermal runaway occur on one battery bank in 
2002, but that was due to other circumstances. However, the insulation probably 
didn't help the batteries cool, in that one instance.  When I got to the site, 
the generator had been running for 3 very hot days, continuously pumping current 
into DRY batteries that should have been flooded.  The batteries had begun to 
melt, and some had become blobs of maroon plastic.  Those L-16s were only five 
years old at the time.
Nick Soleil
Project Manager
Advanced Alternative Energy Solutions, LLC
PO Box 657
Petaluma, CA 94953
Cell:   707-321-2937
Office: 707-789-9537
Fax:    707-769-9037




________________________________
From: Allan Sindelar <allan at positiveenergysolar.com>
To: re-wrenches at lists.re-wrenches.org
Sent: Fri, December 10, 2010 8:36:00 AM
Subject: Re: [RE-wrenches] To insulate a battery bank

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


 
AllanSindelar
Allan at 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.
> 
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