Bus Bars on batteries [RE-wrenches]

Mon Sep 17 14:13:35 PDT 2001

Travis,
We offer our customers a Surrette 2 volt cell the KS-17 that is 883 AH (20hr
rate). It is reasonably priced at $239 retail when picked up from our shop,
or $219 FOB from the distributor in CT. With .265 " thick positive plate
thickness 2,400 (about) 60% DOD cycles are realistic. $3k for a 24 volt
system and $6k for 48v is doable for many folks. Especially the people who
have been through a couple of sets of golf carts or L-16's. At an average of
two 60% cycles per week the KS-17's will last 23 years.
We keep these cells in stock and on charge so that if a customer has a bad
cell we can replace it right away. So far we have not had to replace a
single cell.
The plate thickness of a Concorde AGM battery is .105" (about the same as
most golf cart bats). The Concorde's will cycle 800 times at a 60% DOD
(manufactures number). AGM Concorde's are great batteries for smaller off
grid systems (or for systems with owners with deep pockets) and are the
perfect choice for grid connected systems. But for most off grid systems the
thicker plates and large 2 volt cells just last so much longer that the
payback is too great to ignore.
A 21.2kwhr bank of KS-17's will cost $3,000 and this one set will last for
23 years (at two 60% DOD cycles per week).
To get 23 years of service (in a comparable system) from AGM's you would
need a total of 3 sets at an approximate cost of $8,000 not counting the
labor for the two swap outs.

Dave

-----Original Message-----
From: Travis Creswell, Ozark Solar [mailto:ozsolar at ipa.net]
Sent: Monday, September 17, 2001 3:12 PM
To: RE-wrenches at topica.com
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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>>
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