[Milsurplus] BB590 Repair

[W0rw at aol.com]

i have just finished repairing some BB590's and thought
there might be some guys out there that might need the repair info.
BB590's are 28V, 20 Cell, Large "C" size NiCad battery packs, usually green.
There have been many manufacturers and the inside design varies a lot.
You can detect a bad cell by measuring a low voltage after charge or
after no charge possible.
The usual failure is caused by a shorted cell, some times an open weld.
If the batteries are potted in place it is difficult to remove them, 
some manufacturers used a plastic nest (matrix) to hold the cells and 
replacement
is very easy on these types.
To open the battery you must remove 90% of the large sides and leave the 
narrow side intact. Start by filing or grinding the vertical side edges.
Then hacksaw 2 shallow cuts across the bottom edges of the large side,
1/2 inch from the bottom, this will be the break point for the side panel.
Then chisel the beveled edges and pry the side panel loose, bend it back and 
break it
off at the hacksaw cut.
Now both sides are open and you can probe each cell and find the bad one.
Pull the welds off of the bad cell, cut any retaining plastic away and punch
it out of the nest. Put a new cell in, clean the terminals and tin them,
resolder the new cell in place.
Charge the new cell by it self before recharging the entire pack.
Add insulation as necessary, replace the plastic side panels and
use thick plastic packaging tape to wrap it up.
You can get replacement cells from an old scrap BB590 or from Batteries Plus.
i have repaired 8 or 9 of these puppies.
Paul  w0rw