24
Rev.12/31/97
2.25 WATER TREATMENT FOR OVER SULFATION
2.25 WATER TREATMENT FOR OVER SULFATION
In cases of emergency such as plant power loss or loss of both chargers, a
long discharge to the point of over-discharge may make the battery difficult
to recover. Over sulfation may have occurred such that prolonged charging
set forth in section 2.24 may not recover the battery.
long discharge to the point of over-discharge may make the battery difficult
to recover. Over sulfation may have occurred such that prolonged charging
set forth in section 2.24 may not recover the battery.
The water treatment should only be attempted in an emergency as a
last
last
resort
after prolonged charges will not restore the specific gravity.
The principle is to reduce the specific gravity in steps by removing a portion
of the electrolyte and replacing it with distilled water, then charging the
battery after each step. As the specific gravity is reduced and the charge is
applied, the sulfate is dissolved from the plates by lower specific gravity
electrolyte at each step. The electrolyte becomes more and more like pure
of the electrolyte and replacing it with distilled water, then charging the
battery after each step. As the specific gravity is reduced and the charge is
applied, the sulfate is dissolved from the plates by lower specific gravity
electrolyte at each step. The electrolyte becomes more and more like pure
water, making it easier for the sulfate to transfer off the plates into the
electrolyte. Once the sulphates have been dissolved and removed, the
process is reversed to bring the electrolyte back to normal specific gravity.
electrolyte. Once the sulphates have been dissolved and removed, the
process is reversed to bring the electrolyte back to normal specific gravity.
The steps are as follows:
1. Reduce the specific gravity to about 1.050 to 1.100 by removing some of
the electrolyte and replacing it with distilled water.
2. Charge the battery at the equalizing rate until the specific gravity of the
pilot cell stops rising for two consecutive readings. However, do not
charge longer than 48 hours before the next step.
charge longer than 48 hours before the next step.
3. Again reduce the specific gravity as in step 1 above and repeat the charge
in step 2.
4. Repeat the above steps until the maximum specific gravity obtained at the
end of a charge is less than 1.150.
5. Reverse the above process by removing some of the weakened electrolyte
and replacing it with 1.300 specific gravity acid. The amount to be
replaced is about the same as that in step 1 above. Do not try to speed up
the process by replacing more of electrolyte than that removed in steps 1
through 4.
replaced is about the same as that in step 1 above. Do not try to speed up
the process by replacing more of electrolyte than that removed in steps 1
through 4.
6. Charge the battery as in step 2 above, checking the specific gravity of 10
percent of the cells.
7. Repeat steps 5 and 6, increasing the specific gravity until it is just below
normal operating value. Record the specific gravity of all the cells on the
last step.
last step.
8. Place the battery back under normal float charge and service.