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 Engineer
303 505-8760
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
<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
<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
/http://athens-electric.com/
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