[RE-wrenches] Battery Venting (WAS Passive Battery Venting)

Sun Nov 2 09:08:26 PST 2014

Allan,

That was my plan when he insisted on venting to the outside.

I use the Zephyr Power Vent for liquid lead acid batteries. When 
replaced the liquid electrolyte batteries in our backup system with 
AGM, we turned off the Zephyr and took the door off the battery box. 
I showed it to the client. I think when you use the word hydrogen to 
many people they think of the Hindenberg disaster.

Has New Mexico ever come to conclusions concerning venting sealed 
batteries to the outside, or is it still in limbo?

Thanks,

Drake

At 11:39 AM 11/2/2014, you wrote:
>Drake,
>My suggestion is that to achieve the client's wishes as well as your 
>own cooling concerns, you include a Zephyr Power Vent in a 2" PVC 
>vent stack to the outside. Let the charge controller's 
>voltage-actuated auxiliary setting power the vent (it's OK to do so 
>directly on Outback and Midnite controllers, and I believe all other 
>major ones as well). As these are sealed batteries,they won't gas 
>significantly under normal charge voltages. Set the turn-on voltage 
>at the gassing voltage, or thereabouts depending on your 
>determination. This will be above (or below but near) normal charge 
>voltage, and will cause the Power Vent to turn on only under 
>abnormal conditions. The Power Vent also has a backdraft damper 
>built in (which is why it must be oriented vertically) so will 
>prevent excessive convective heat loss when not running.
>
>This won't address the possibility of one cell failing and gassing, 
>as the string voltage determines turn-on. However, as others have 
>pointed out, that may be of benefit: if one cell fails you'll still 
>be able to smell it and address the problem.
>Allan
>
>Allan Sindelar
><mailto:allan at sindelarsolar.com>allan at sindelarsolar.com
>NABCEP Certified PV Installation Professional
>NABCEP Certified Technical Sales Professional
>New Mexico EE98J Journeyman Electrician
>Founder (Retired), Positive Energy, Inc.
>505 780-2738 cell
>
>
>On 10/29/2014 6:19 PM, Drake wrote:
>>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>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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