Precision Trading 60 R3.0 - Manual (Page 60)

Operator Manual, Supercharger 60 R3.0
Page 60 of 62
12. BATTERY TESTING NOTES
Note, hazardous condition: Handle batteries with extreme care as they are capable of very
high discharge rates if short circuited.
Check the Battery Manual, IMM or Aircraft Manufacturer Instructions for information on
charging, discharging and testing.
The Charge & Float and the Charge & Peak Stop modes are particularly useful with lead acid
batteries, where the battery voltage is a better indicator of the state of charge, as compared with
Nickel-Cadmium batteries where terminal voltage gives little information on the state of
charge.
Lead-Acid batteries are normally float charged (constant voltage) typically at 2.3V/cell. A 6
cell pack (12V) will then be float charged with the voltage selector at 13.8V. In this mode, the
charge current is set to the highest level that the cells will safely take (typically up to 1C
depending on the battery type and specific manufacturer’s instructions). This will be the charge
current until the float voltage is reached, at which time the current will diminish to the level
needed to maintain the float voltage.
Lead-Acid batteries can also be charged in a manner in which it is possible to know much
better the end of charge. When a Lead-Acid cell is charged with constant current at C/15 to
C/10, the end voltage will rise rapidly at about 90 to 95% of charge, which occurs at about 2.4
to 2.45V/cell. A 5A-hr, 6 cell pack, can be charged at 335mA to 500mA, with the voltage
selector at 14.7V. The CHARGER-ANALYZER will stop the charge operation when the rapid
rise of end-of-charge voltage is detected.
For Nickel-Cadmium batteries, the most effective charge method is constant current vs time. In
the absence of any particular instructions from the manufacturer, charging at c/10 for 12 to 16
hours will insure a complete charge.
The Nickel-Cadmium batteries can also be charged in the float mode, with a voltage of 1.4
V/cell (a 20 cell battery would be set to 28.0V).
NOTE: Prolonged use of the float (constant voltage) method on Nickel-Cadmium batteries will
result in cell imbalance, which could eventually lead to premature cell failure due to un-even
charge acceptance and un-even discharge capacity.