Bus Bars on batteries [RE-wrenches]

[Tom Elliot]

Travis, the problem I have with 2 volt cells is that you are trying to
overcome the shortcomings of "parallelism" by introducing another weakness.
The failure of any one 2 volt cell in such a large series installation
renders most, if not all, of the bank, unusable.

What I like about my system is that I can have as many series strings
connected to my system as I want even if a battery or two should fail I
still have most of the capacity of my system available.

Tom

----- Original Message -----
From: "Travis Creswell, Ozark Solar" <ozsolar at ipa.net>
To: <RE-wrenches at topica.com>
Sent: Monday, September 17, 2001 9:11 AM
Subject: Re: Bus Bars on batteries [RE-wrenches]


> To me, it's another argument for 48 volt systems and the big two volt
cells.
>  I wish I could get more folks to cough up for the big 2 volt cells but
they
> are ridiculously expensive and to date I have only one set of the big
> Surrettes,1104 ah's @ 48 volts (one series string).  They seem to be more
> charge efficient and have as lower self discharge than the golf carts and
> L-16's I have seen.  But I have way to prove that.
>
> Why are the big 2 volt cells so expensive?  Is there any reason other than
> low production volumes?  On paper they are a lot cheaper per cycle than
> L-16's but 10 grand vs. 2 grand is pretty hard to justify no matter how
long
> they last.
>
> Travis Creswell
> ----------
> >From: Tom Elliot <telliot at wagonmaker.com>
> >To: RE-wrenches at topica.com
> >Subject: Re: Bus Bars on batteries [RE-wrenches]
> >Date: Mon, Sep 17, 2001, 1:23 PM
> >
>
> >Bill,
> >
> >My original post and my installation are not about battery
*interconnects*
> >but about the connections between batteries (or series connected
batteries)
> >and a *main buss* (see http://www.wagonmaker.com/newbatt.html to see what
I
> >mean).  In my installation the series pairs are interconnected with 1/0
> >cables and the pairs are connected to the main buss with 1/0 cables.  It
> >isn't about stress on battery terminals or replacing cables it is about
the
> >wiring scheme itself.
> >
> >A main buss is designed as the central connection point for all series
> >strings in order to eliminate the parallel battery connections that are a
> >weak point in battery banks.
> >
> >We've all known for a long time that too many paralleled series strings
is
> >not good.  What surprises me now is that we could think that *any*
parallel
> >connected series strings are a good idea.  If a parallel connection is
good
> >then it should be no problem for any number of series strings.  By
limiting
> >ourselves to only 3 or 4 parallel strings we are keeping the problems at
a
> >low enough level that they don't show up right away.
> >
> >It seems to me that we can just eliminate the problem entirely by
> >eliminating any parallel strings and connecting the batteries and
inverter
> >together through a main buss that evenly distributes charge/discharge
across
> >all the series strings.
> >
> >Tom
> >
> >
> >----- Original Message -----
> >From: "Bill Brooks" <billbrooks7 at earthlink.net>
> >To: <RE-wrenches at topica.com>
> >Sent: Monday, September 17, 2001 5:31 AM
> >Subject: RE: Bus Bars on batteries [RE-wrenches]
> >
> >
> >> Bob,
> >>
> >> In my mind the issue is whether the busbar was designed to be used with
> >that
> >> particular battery. Since the only battery systems to be listed are
UPSs,
> >> anything we do with batteries could probably be challenged by an
> >inspector.
> >>
> >> My personal preference is flexible cables like those that Trace sells.
The
> >> key benefit of flexibility is that it does not stress the battery
> >terminals.
> >> Busbars and rigid cables can stress terminals unless they have been
> >designed
> >> as part of a system where terminal stress has been considered in the
> >> engineered design.
> >>
> >> Our industry is in desperate need of listed battery systems. It will
make
> >> inspection much more straightforward.
> >>
> >> Bill.
> >>
> >> > -----Original Message-----
> >> > From: Bob Ellison, Alternative Energy Systems
[mailto:ellison at gisco.net]
> >> > Sent: Monday, September 17, 2001 7:36 AM
> >> > To: RE-wrenches
> >> > Subject: Bus Bars on batteries [RE-wrenches]
> >> >
> >> >
> >> > Can anyone tell me where in article 690 of the NEC that bus bars are
> >> > excluded from use in home power systems?
> >> > I had a discussion with a telecom designer and they use them all the
> >time.
> >> >
> >> > Thanks,
> >> > Bob
> >> >
> >> >
> >> > RE. Ellison
> >> > Supplier of;
> >> > Diesel Generators &
> >> > Alternative Energy Systems & Supplies
> >> > 34642 Countryman Road
> >> > Theresa, NY. USA
> >> >                               13691-2076
> >> >
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