Battery choice: one string or two? [RE-wrenches]

[Tom Elliot, Guffey Energy Works]

Rather than explain it again I'll give you to a page on my website with
pictures and an explanation.

http://www.wagonmaker.com/newbatt2.html

What I have is 12 strings, with each string independently connected to the
buss bars. that way each string provides power to the system independently,
i.e. not sending its power through daisy chained strings.  I'm convinced
that this habit of daisy chaining came about because early on in the
industry people just didn't use large battery banks, systems tended to be
small, so a couple of strings connected to each other was not a problem.
But as banks and systems got bigger the tendency was to just daisy chain a
few more strings to increase capacity.  But frankly no on in the business of
creating large banks uses that method and when I got to talking with a large
wholesaler who routinely installs large battery banks for telcos they were
amazed that it was being done at all, let alone with multiple strings.

I also think relying on a single string is risky because any failure at all
and the customer is out of luck.  With my system a cell or a battery can
fail and it is no problem to disconnect it from the bank, without ever
taking the rest of the bank out of service.

Tom


----- Original Message -----
From: "Darryl Thayer" <daryl_solar at yahoo.com>
To: <RE-wrenches at topica.com>
Sent: Wednesday, October 08, 2003 9:45 PM
Subject: Re: Battery choice: one string or two? [RE-wrenches]


> Hello Tom
> How is bussbars different? Do you mean paralleling the
> cells? and then the string?
> Daryl
>
> --- "Tom Elliot, Guffey Energy Works"
> <telliot at wagonmaker.com> wrote:
> > I guess this is where I step in and mention buss
> > bars.  A single string is
> > prone to failure of the entire bank if only one cell
> > fails, something you
> > would have to design for, IMO, because it is always
> > possible to get a flawed
> > battery that doesn't show its true colors until it's
> > been in use for a
> > while.  With a buss bar you don't "daisy chain" and
> > have the problems that
> > brings but you have the redundancy you need to
> > protect from problems.
> >
> > Tom
> >
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