Battery Bank Venting [RE-wrenches]
Darryl Thayer
daryl_solar at yahoo.com
Sat Apr 26 11:20:45 PDT 2008
Hi Larry
Yes I have been/seen case of thermal runaway, one case
the sun comming in a window, on 4 parallel strings,
the one with sunlight on overheated, started on fire.
What I believe happened is the warm batteries were
charging and overheated, because all the charge was
being taken by this battery, and the higher
temperature caused the other batteries to discharge
into the hot batteries amaking them hotter.
The second case was not as obvious, so my
understanding is less, but I believe the same senerio
of hot battery getting extra discharge is the cause.
I also have the case of a flooded lead acid (antomony)
that was four strings in parallel, the whole bank
charging at C/10 and one battery in on of the strings
melted and caught fire.
Darryl
--- "Larry Crutcher, Starlight Solar"
<larry at starlightsolar.com> wrote:
>
>
> Darryl,
>
> 99% of the work we do is battery based. I have been
> installing AGM batteries (Deka, Lifeline, Concorde,
> Sun Xtender, Optima) for many years. I'm curious why
> you warn against parallel strings and thermal
> runaway? Have you experienced any of problems?
>
> Out of hundreds of batteries installed, I have never
> had a case of thermal runaway. If fact, AGM's in
> general have been the most reliable batteries we
> have sold. There seems to be no limit to the charge
> current these batteries can handle. Do you have any
> actual experience of "excessive charge rate frying
> AGM's"?
>
> I have had only two batteries that have vented. Both
> had a defective cell as measured by resting voltage.
> Some of our customers severely abuse small 12 volt
> banks of 2 or 3 series/parallel strings of 6 volt
> Lifelines. After 8 to 10 hours of equalization at
> 15.5 volts, these banks returned to nearly full
> capacity and are still in use. Also, I have been
> buying batteries for the last year and many 4D and
> 8D AGM's have come in. Most of these are at 10 volts
> or less when they arrive. I can restore about 80% of
> these and have been reselling them as good used
> batteries.
>
> Richard, from my experience with AGM's I would not
> hesitate to install the bank in the location you
> have described.
> Larry Crutcher
>
>
>
> ----- Original Message -----
> From: Darryl Thayer
> To: RE-wrenches at topica.com
> Sent: Thursday, April 24, 2008 4:20 PM
> Subject: RE: Battery Bank Venting [RE-wrenches]
>
>
>
> Be careful of thermal runaway. Do not parallel
> strings. with this caveats I think it is safe to
> have
> these batteries indoors. Has anyone tried a
> hydrogen sensor, I have heard that the hydrogen
> will
> rise faster than diffuse, So a hydrogen sensor in
> the
> top of a sealed cover should detect hydrogen
> before
> any accumulation.
>
> A properly operating AGM should not release any
> H2,
> but of course thermal runway or excessive charge
> rate
> will fry the batteries.
> Darryl
>
> --- Richard Bogan <rbogan at empire-solar.com> wrote:
>
> >
> > 12
> >
> > Richard J. Bogan
> > NABCEP Certified Solar PV Installer (r)
> > Solar Operations Manager | Empire Solar
> Solutions,
> > LP
> > cell 562-755-7389 | fax 708-202-6144
> >
> > -----Original Message-----
> > From: Mark Frye [mailto:markf at berkeleysolar.com]
>
> > Sent: Thursday, April 24, 2008 4:05 PM
> > To: RE-wrenches at topica.com
> > Subject: RE: Battery Bank Venting [RE-wrenches]
> >
> >
> > How many of these sealed batteries do you intent
> to
> > install?
> >
> > Mark Frye
> > Berkeley Solar Electric Systems
> > 271 Vistamont Dr
> > Grass Valley CA 95945
> > (530) 401-8024
> > www.berkeleysolar.com
> >
> > -----Original Message-----
> > From: Richard Bogan
> [mailto:rbogan at empire-solar.com]
> >
> > Sent: Thursday, April 24, 2008 4:03 PM
> > To: RE-wrenches at topica.com
> > Subject: Battery Bank Venting [RE-wrenches]
> >
> >
> > Hello wrenches,
> >
> > We have a battery back-up / interconnected
> system
> > utilizing PVX-2580L
> > Sealed
> > AGM SunXtender batteries. The battery bank will
> be
> > located inside a
> > utility
> > room which is part of a large 2000 sqft
> underground
> > garage.
> > The room has mechanical venting out into the
> garage.
> > The garage has
> > 8-10'
> > ceilings and a large double garage door that
> goes up
> > to ground level.
> > It
> > also has a couple of doors to finish portions of
> the
> > basement (wine
> > cellar,
> > maid quarters, Rec. room) and 2 stairways up to
> the
> > first floor living
> > area.
> >
> >
> > Standard practice for us is to have venting but
> in
> > this case the
> > basement
> > walls are ~16" solid concrete walls with no
> > available openings for a fan
> > to
> > push air outside. We contacted the battery
> > manufacture and they gave us
> > a
> > reality scenario where the chances of enough
> > hydrogen to accumulate in
> > this
> > large of area to reach an explosive level is
> > impossible BUT, they are
> > not
> > fire experts and we should consult with our
> local
> > fire department for
> > guidance.
> >
> > If we have to we will core a hole into the
> > foundation install a fart fan
> > and
> > ducting but, I wanted to get your thoughts
> before
> > that fun job.
> >
> > Thank you!
> >
> > Richard J. Bogan
> > NABCEP Certified Solar PV Installer (r) Solar
> > Operations Manager |
> > Empire
> > Solar Solutions, LP
> >
> >
> > The information contained in this message may be
> > confidential and is for
> > the
> > intended addressee only.
> > Any unauthorized use, dissemination of the
> > information, or copying of
> > this
> > message is prohibited.
> > If you are not the intended addressee, please
> notify
> > the sender
> > immediately
> > and delete this message.
> >
> >
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