Edison batteries [RE-wrenches]

[Travis Creswell, Ozark Solar]

Hi John,

Generally speaking that type of battery would be around 4 times as energy
dense as lead acid and you  can discharge it all the way without drastic
reduction of cycle life.  Assuming that you would never take a lead acid
battery below 50% then an Edison type of battery has approximately 8 times
more usable energy per lb.  That part has always really impressed me. 
Imagine using T-105's that had 880 ah's of usable energy compared to the
usual 110 ah's.  That's where the advantages end.

They are nominally 1.2 volts per cell vs. 2 volts per cell for lead acid.  I
believe to fully charge them you need to take them to 1.6 volts per cell or
better.  That means 16 volts for a 12 volt pack which is pretty hard to do
with solar panels since in the anything but the dead of winter many modules
peak power point is under 15.5 volts.

They self discharge at least twice as fast as lead acid and are no where
near as charge efficient as lead acid.  Those two items make them a very bad
choice for a PV only RE system.  They would be more suited for a wind/hydro
site that regularly produces more than is needed.

I'm sure others will also have good advice for you.  I would guess the
capacity to be 120 AH's.

Travis
----------
>From: john at gosolar.co.nz
>To: "RE-wrenches at topica.com" <RE-wrenches at topica.com>
>Subject: Edison batteries [RE-wrenches]
>Date: Mon, Jan 7, 2002, 5:19 PM
>

>Hi there,
>
>This may be duplicating a past listing, however....
>
>I just picked up a new customer that took over an existing system. This
>system is using Edison batteries.  The indentation on the battery case
>is ED-120.
>
>However the actual labels say thay are Edison Ni-Cads.  They come in a
>pack of 5 per case. And they have a lid on the top for what appears to
>be adding and checking electrolyte.
>
>Anyone heard of these, how long do they last, what should individual
>cell voltage be, what is the a/h rating?  Anything else I should know
>about them.
>
>What is confusing is that I thought that all Edison batteries were
>Ni-Fe.
>
>        thanks for any help provided,            John Veix
>
>

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