[AT] desulphating battery chargers

[Howard R. Weeks]

In a past life,  I was responsible for several telephone exchanges and a
tandem switch or two.
All of them used a bank of lead acid batteries to provide the 48 volt
battery for the system.
The batteries were roughly 2 volts DC each and held about 5 gallons of acid
in each battery.
The containers were all glass.  I don't ever remember having to change out a
battery but we did
change the acid in them about once every other year.

Also had an audodin data switch that had a string of 120 batteries in series
producing a bit under
270 volts DC.  It was arranged with two rows of 30 batteries on the bottom
rack with a similar number
on an open rack above the first set of 60.  One of the jars on the upper
rack developed a small hairline
crack which was seeping.  One night, this crack opened up a bit and dumped
acid down on the lower
rack of batteries.  This triggered a melt down of about 6 of the lower
batteries and one of the upper ones.
Fire department would not go near it.  Fire extinguishers would not touch
it.  White cloud of acid fumes
coming out of the battery room.  We borrowed a closed circuit breathing
system from the fire department
and one of our maint guys went in and disconnected the melting batteries
from the rest of the string.  That
stopped the melt down.

I will never understand why it did not explode. (1975 in Germany)

Howard Weeks
Harlem, GA