One AHJ actually got me on this with sealed batteries. I've blown the seal out overcharging a sealed battery too, so this is a real possibility. The venting requirements are not near as stringent though as for a flooded cell. Article 480 says we need to prevent the build up of explosive gases, which isn't very hard considering how hard it is to contain hydrogen. I demonstrated to the AHJ that the steel enclosure had a 1/4" gap x 12' of edge around the door (36 sq in) which is more venting than a 6" diam PVC pipe. I also showed that hydrogen does not become explosive until you reach over a 4% hydrogen to air mixture, so you have to consider the volume of the battery box as well. He accepted all of this, which was good, because the battery box was set into the ground (for thermal stabilization) and would have been very hard to change. (He still made me change one PVC elbow to Schedule 80, what a stickler!)
R. Walters [email protected] Solar Engineer On Dec 14, 2010, at 8:47 AM, Dana wrote: > Interesting in that our AHJ are not up to speed on this. Sealed is sealed to > them and now I know too. > > Thanks > > Dana Orzel > Great Solar Works, Inc > E - [email protected] > V - 970.626.5253 > F - 970.626.4140 > C - 970.209.4076 > web - www.solarwork.com > > "Responsible Technologies for Responsible People since 1988" > Do not ever belive anything, but seriously trust through action. > > From: [email protected] > [mailto:[email protected]] On Behalf Of Exeltech > Sent: Tuesday, December 14, 2010 5:54 AM > To: RE-wrenches > Subject: Re: [RE-wrenches] To insulate a battery bank DEPENDS on a lot of > factors. > > If sealed batteries are inadvertently overcharged, H2 and O may be created at > a rate beyond which the two gasses can be recombined within the cells. In > this case, internal seals may open to prevent excessive pressure from > accumulating and turning the battery into an explosion hazard. Venting of > the enclosure is needed for the same reason. Though sealed batteries are > less likely to require venting - it's a necessary safety precaution. > > Dan > > > --- On Mon, 12/13/10, jay peltz <[email protected]> wrote: > > From: jay peltz <[email protected]> > Subject: Re: [RE-wrenches] To insulate a battery bank DEPENDS on a lot of > factors. > To: "RE-wrenches" <[email protected]> > Date: Monday, December 13, 2010, 6:30 PM > > Hi Dana, > > The manufacturers that I've read, do say they should be in a vented enclosure. > But your point is taken, > > thanks, > > jay > > > On Dec 13, 2010, at 8:32 AM, Dana wrote: > > > Sealed batteries do not require a vent , therefore no air passage – less > influence of ambient exterior temps to the bank. Perhaps on a small bank this > would have an influence. > On a large bank in a low usage scenario, IE: second home with no one home, > the system may be full by 10AM and the fan runs for most of the day inducing > cool air. > > Granted most systems have a present [physically] home owner. I have many > systems that float for a good part of the winter, awaiting the arrival of > either the owner for a week or spring. > > Dana Orzel > Great Solar Works, Inc > E - [email protected] > V - 970.626.5253 > F - 970.626.4140 > C - 970.209.4076 > web - www.solarwork.com > > "Responsible Technologies for Responsible People since 1988" > Do not ever belive anything, but seriously trust through action. > > From: [email protected] > [mailto:[email protected]] On Behalf Of jay peltz > Sent: Sunday, December 12, 2010 4:49 PM > To: RE-wrenches > Subject: Re: [RE-wrenches] To insulate a battery bank DEPENDS on a lot of > factors. > > HI Dana, > > I'm curious about why you differentiate sealed vs. flooded batteries? > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: [email protected] > > 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 > > > > -----Inline Attachment Follows----- > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: [email protected] > > 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 > > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: [email protected] > > 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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