To do it totally passive you will need a long (tall) pipe up the side of the building, probably painted a dark color to have the sun help warm the tube to help encourage it to vent up, not draw into the building. Put a 180 on the top to keep the rain out and a screen to keep out the bugs.
With outside venting the batteries will just draw in room temperature air, if the room is 70 the battery min temp will be 70. If they are in a basement they will naturally draw in outside air, run the vent as high as you can to help prevent that. If you are using a Classic use the relay to turn the fan on and off at a specific battery voltage. Use a brushless fan and a voltage powered relay if no other choice. Do not put the relay in the battery box! Sealed batteries do need to be vented. I have seen them gas when things go wrong, not pleasant. I wouldn't do it without a fan for LA batteries but it would work for sealed. If the home has a makeup air system or huge exhaust system all bets are off. Just some thoughts, Bob Ellison -----Original Message----- From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Drake Sent: Wednesday, October 29, 2014 8:19 PM To: RE-wrenches Subject: Re: [RE-wrenches] Passive Battery Venting Hi Daniel, I typically vent them the way you do, which will allow any small amount of hydrogen out. The customer is absolutely adamant about venting these to the outside. I will cooperate so long as his method doesn't compromise the system through cooling the batteries unnecessarily in the dead of winter. He is a lawyer and came to the conclusion of the need for venting to the outside from reading the NEC which says that sealed batteries "require the same amount of ventilation" as liquid lead acid batteries. The code also says to vent appropriate to battery technology, so the code says two conflicting things. On the other hand, it doesn't say that liquid electrolyte batteries need to be vented to the outside. They will sure stink if you vent them to the inside. Drake At 09:54 AM 10/29/2014, you wrote: >I just re-read the original post Drake. These are AGM batteries. Do you have >a "belt, suspenders,...then a rocket pack" type of client here? > >We typically vent our AGM boxes with small louver vents top and bottom to >allow the batteries to ventilate for cooling purposes, not H2 concerns. > >With Regards, > >Daniel Young, >NABCEP Certified PV Installation ProfessionalTM: Cert #031508-90 >NABCEP Certified Solar Heating InstallerTM: Cert #SH031409-13 > >-----Original Message----- >From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On >Behalf Of Ray Walters >Sent: Tuesday, October 28, 2014 11:12 PM >To: RE-wrenches >Subject: Re: [RE-wrenches] Passive Battery Venting > >That's why we usually have the batteries in a garage, basement, or out >building that is not open to the living space. >I've seen some cases of very well sealed and insulated enclosures allowing >batteries to over heat, and also build up a lot of acid damaged connections. >Boxes I've seen with more air space and less sealing don't get this build >up, but you're correct: they do occasionally allow H2S into the surrounding >area. > >R.Ray Walters >CTO, Solarray, Inc >Nabcep Certified PV Installer, >Licensed Master Electrician >Solar Design Engineer >303 505-8760 > >On 10/28/2014 8:10 PM, Jerry Shafer wrote: > > > > We do what we can to seal the enclosure so if or when a battery fails > > and really gasses off the two vents on the same wall regardless of > > wind direction will vent the gas. If it is not sealed then the gas can > > travel through out the area this is not advised. > > > > > >_______________________________________________ >List sponsored by Redwood Alliance > >List Address: RE-wrenches@lists.re-wrenches.org > >Change listserver email address & settings: >http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > >List-Archive: >http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > >List rules & etiquette: >www.re-wrenches.org/etiquette.htm > >Check out or update participant bios: >www.members.re-wrenches.org > > > >----- >No virus found in this message. >Checked by AVG - www.avg.com >Version: 2012.0.2247 / Virus Database: 4031/7973 - Release Date: 10/29/14 > >----- >No virus found in this message. >Checked by AVG - www.avg.com >Version: 2012.0.2247 / Virus Database: 4031/7973 - Release Date: 10/29/14 > >_______________________________________________ >List sponsored by Redwood Alliance > >List Address: RE-wrenches@lists.re-wrenches.org > >Change listserver email address & settings: >http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > >List-Archive: >http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > >List rules & etiquette: >www.re-wrenches.org/etiquette.htm > >Check out or update participant bios: >www.members.re-wrenches.org _______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org _______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
