(ET) E20 cells replaced

[Chris Zach <cz alembic crystel com>]

Finally finished replacing the E20 rear string of 20 cells. After 20 
years it is a job to do, here are some of the key issues:

1) Holes should be tapped.

I have no idea why but when I remove the stainless steel bolts after 20 
years I find either brown "dirt" or black tarnish on the cells. No idea 
why but in order to re-use the stainless steel bolts I need to clean 
each one with my grinder/wire wheel in order to re-use them.

Also I've found it's a good idea to re-tap the holes which once again 
results in a small amount of brown crud to come out in a powder format. 
No clue what that is, but there it is.

2) The nickel plated interconnects hold up fairly well.
Now this is in an E20 that has been stored outside, driven rather hard, 
and bounced around in the battery box for 2 decades, but oddly enough 
the John Lussmeyer nickel plated cell interconnects are not too bad. 
Some of them have some corrosion right at the slots for the bolts, some 
of them were dirty on the bottom, but none of them showed signs of 
serious damage or disintegration. This is pretty good since the 
interconnects are copper on the inside with nickel plating on the 
outside, but they seem to be holding up well.

Still a few have nicks, and copper sulfate is visible at those places. 
So in other 20-40 years they may need replacing, we shall see. Note that 
on cells I have had stored for 15 years I see no damage on the 
interconnects.

3) Batteries need to be removed and the posts cleaned.

While the interconnects are good, the battery posts almost always have a 
lot of tarnish that needs to be cleaned off with a wire wheel. Not sure 
if this caused resistance in the overall pack of cells, but when 
removing the connections you need to clean off the battery posts.

4) If a cell has 0 volts after a charge attempt it's shorted.
In a charge failure accident the cells will short due to heat melting 
the polypropylene separators and warping the plates. Sad, but this seems 
to be the way to kill these batteries.

More later.
C