Alpha Technologies Nickel Cadmium Clear Case - Technical Manual - Manual (Page 10)

NI-CD-CLEAR-CASE 10
2.0 Electrolyte, continued
2.3 Topping Up
Since water electrolysis and evaporation are constantly taking place in the cell, causing the
electrolyte level to lower over time, occasional topping up of the electrolyte is needed.
Check the electrolyte level visually from the outside of the cell.
Keep the electrolyte between the minimum and maximum level marks. Only use distilled
or ion-exchange purified water to top off the electrolyte.
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NOTE:
Charging accelerates the loss of water from the cell. Be sure to top up the cell before a charge or recharge.
2.4 Renewal
Over time, the density of electrolyte slowly decreases and it may accumulate various
contaminates. Therefore, it is necessary to renew the electrolyte periodically. A renewal
should generally be conducted once every five to six years, during which time, the specific
gravity will likely have fallen to the lowest limit.
Renew the electrolyte in the cell when:
The specific gravity has fallen below 1.16/68ºF (1.16/20ºC).
The cells fail to work at the rated capacity.
Contaminates or foreign materials, such as potassium carbonate, in the electrolyte have
accumulated beyond 100 grams per liter.
Renewal Steps
Discharge the battery to 0.6–0.8Vpc at a 5 hour rate current (C
5
).
After discharging, disconnect each cell from the string.
Open the filler cap of each cell, insert a siphon through the filler tube, and drain the old
electrolyte completely. Dispose of the electrolyte in accordance with applicable local,
state, and federal regulations. See section 2.1 Electrolyte Notes for more information.
Do not allow the cells to remain empty for too long or rinse the interior with water. Fill up
each cell with new electrolyte, using a funnel and a jug (both supplied). Only use type
HONDA B-20 or A electrolyte. Ensure the specific gravity of the solution is 1.21 ± 0.01.
Close the vent valves and clean the outside of each cell.
Make sure all cells are put in place and properly connected as they were before.
Conduct an equalizing charge according to section 3.3.
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