[RE-wrenches] Passive Battery Venting

Fri Oct 31 13:20:34 PDT 2014

Drake,
Please explain what might happen if something went wrong with one battery, when they are not vented to outside. How would we know it?  Thank you. 

Phil Forest
South Mountain Company

> On Oct 31, 2014, at 8:42 AM, Drake <drake.chamberlin at redwoodalliance.org> wrote:
> 
> One big advantage of not venting AGM batteries to the outside is that when something goes wrong you will know it. A well vented system could have one bad battery ruin the entire pack before the problem was detected.
> 
> 
> At 08:12 AM 10/30/2014, you wrote:
> 
>> 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-bounces at 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-bounces at 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.
>> > >
>> > >
>> >
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