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Commonly Used Terms
A, mA:
Unit of measurement relating to a charge or discharge current. 1000 mA = 1A (A = Ampere, mA =
Milliampere).
Ah, mAh:
Unit of measurement for the capacity of a battery (Amperes x Time Unit; h = hour). If a pack
is charged for one hour at a current of 2A, it has been fed 2Ah of energy. It receives the same quantity of
charge (2Ah) if it is charged for 4 hours at 0.5A, or 15 minutes (=1/4 hour) at 8A.
‘C’ - Rating:
Capacity is also referred to as the ‘C’ rating. Some battery suppliers recommend charge
and discharge currents based on the battery ‘C’ rating. A battery’s ‘1C’ current is the same number as the
battery’s rated capacity number, but noted in mA or amps. A 600mAh battery has a 1C current value
of 600mA, and a 3C current value of (3 x 600mA) 1800mA or 1.8A. The 1C current value for a 3200mAh
battery would be 3200mA (3.2A).
Final Charge Voltage:
The voltage at which the battery’s charge limit (capacity limit) is reached after
which the charge process switches from a high current to a low maintenance rate (trickle charge). From
this point on, any further high current charging would cause overheating and eventual terminal damage
to the pack.
Nominal Voltage (V):
The nominal voltage of the battery pack can be determined as follows:
- NiCd or NiMH:
Multiply the total number of cells in the pack by 1.2. An 8-cell pack will have a nominal
voltage of 9.6 volts (8 x 1.2).
