[RE-wrenches] Passive Battery Venting

[Drake]

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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