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     Date: 04-19*94    Time: 11:26a     Number: 1215  
     From: DON KULHA                     Refer: 0      
       To: ALL                        Board ID: FAMILY          Recvd: No
  Subject: EDTA 4 OF 5                      47: Home Power     Status: Public
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Enter a pressing need
Then all of a sudden (in the space of six days) one of the L-16Ws
in the main Home Power system (4@ L-16W) at Agate Flat developed a
shorted cell.  As distressing as it was to lose an eleven year old L-16W
battery, it was fascinating to watch and record the death of one
of its cells.  The shorted cell dramatically unbalanced the remaining
three L-16Ws in the pack.  I had to do something quick.  I disconnected
the series string of two L-16Ws with the bad cell.  Putting a new
L-16W in this eleven year old pack was out of the question.  I started
thinking used battery and imagined the EDTA treated L-16Ws.  Next
day, I removed one of the EDTA treated L- 16Ws from Bob-O's trailer
and inserted it the main Home Power battery.  I had trouble choosing
the best of the two EDTA treated batteries.  I went for the one that
had the least voltage variation between cells.
EDTA treated L-16W performance
I had no idea what to expect.  The last time I tested the sulphated
L-16W it wasn't able to power up a car tail light.  I inserted it into
the main pack as follows in the illustration below.  I gave each
cell a number and recorded data on the performance of the battery
on a cell by cell basis.  The L-16W battery containing cells 1, 2,
and 3 is the EDTA treated battery.  The remaining L-16Ws (cells 4
through 12) are the original, untreated, eleven year old batteries.
What happened?
I'll cut to the chase here.  The L-16W treated with EDTA had regained
enough of its electrical capacity to function as an equal element
with the battery.  It works!  What follows below is data from the
all cells making up this battery under a variety of conditions. 
Detailed in the tables below are a variety of data, here's a score
card to help tell the players:
 Battery Data
1. The date.
2. The battery Ampere-hour Meter reading which indicates
   The pack's State of Charge (minus indicates discharge amp-hrs.).
3. The discharge or charge rate in Amperes (minus indicates discharge). 
   Individual Cell Data
4. The voltage of each cell.
5. The absolute cell voltage deviation from the average cell voltage.
6. The average battery (that's three cells in a case) voltage deviation.
   Note EDTA treated cells' data (Cells #1, #2, & #3) are printed in bold
Derived Cell Data
7. Average cell voltage.
8. Cell voltage standard deviation (computed via standard statistical method)
9. Maximum cell voltage difference.
(continued)
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