[RE-wrenches] Passive Battery Venting

Jerry Shafer jerrysgarage01 at gmail.com
Tue Oct 28 19:10:18 PDT 2014


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.
On Oct 28, 2014 4:06 PM, "Ray Walters" <ray at solarray.com> wrote:

>  That's an interesting idea, but all the failed designs they illustrate
> don't show the way we usually do it.  We don't even bother with an inlet,
> as most battery boxes have enough gap around the door to provide intake
> air, then the exhaust comes off the top with several feet of rise to
> prevent back drafting.  If its in any space that H2s may be a problem
> (living space), we always add a Zephyr Power vent which has a back draft
> preventer.  Even if the Zephyr fails, there will still be passive air flow
> up the pipe past the fan.
> I see 4 problems with their setup:
> 1) Large Copper pipe is really expensive, and steel is hard to work with
> and fittings are expensive.
> 2) Metal pipe is not only thermally conductive, its also electrically
> conductive.  I try to avoid unnecessary conductors in the battery box.
> 3)  Metal pipe will corrode when exposed to H2S and battery acid.  That's
> why we always use plastic.
> 4) Their suggested pipe size (1" outside pipe) are way too small to
> provide venting for any more than a couple of golf cart batteries.
>
> Basically, heat exchanger = good idea, but their version = not.
>
> As for the battery pass through connectors: they seem to be adding
> unnecessary connections, and would also prevent using conduit.  I'd guess
> they're not UL listed, so that whole idea is also code compliant.  Duct
> seal will prevent the H2S from going up the conduit into the DC load center.
>
> They're trying to seal the box too much; the only time you could actually
> have an explosive build up of H2S is if you sealed every gap on the battery
> box.  I think its easier and safer to keep the gaps, and if your venting
> fails, at least it won't blow up or over heat.
>
> R.Ray Walters
> CTO, Solarray, Inc
> Nabcep Certified PV Installer,
> Licensed Master Electrician
> Solar Design Engineer303 505-8760
>
> On 10/28/2014 4:28 PM, Drake wrote:
>
> Hello Wrenches,
>
> A client wants to use a passive battery venting method with a heat
> exchanger to the outside for his bank of Full River AGM batteries. Below is
> a link to one site that recommends this method. Has anyone used this
> method?
>
>   http://www.bdbatteries.com/hydrogenventing.php
>
> My main concern for about the batteries is that they not get cold and lose
> capacity during the short days when storage is most needed.
>
> He would also like to connect the terminals inside the box to a pass
> through jumper http://www.bdbatteries.com/lugs.php?id=269 and then run
> the cables, without conduit, to the inverter. As far as I know, conduit is
> always required on the battery cables even if fuses are used in the battery
> box. Has anything changed?
>
> Thanks,
>
> Drake
>
> Drake Chamberlin
>
>
>
>
>
> *Athens Electric LLC OH License 44810 CO License 3773 NABCEP Certified
> Solar PV 740-448-7328 <740-448-7328> *http://athens-electric.com/
>
>
>
>
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