INDEX
10
MULTI-CHEMISTRY AC PEAK DETECTION BALANCE CHARGER
Understanding C Ratings:
Many battery manufacturers do not list the definition of or explain the purpose of C ratings and how to use that information. For LiPo batteries there
is typically listed both a C rating for charging and discharging of the batteries. You must use caution that you calculate your charge rate based on
the charge C rating and not the discharge C rating.
• Charge Rate Calculation
› The charge C rating of a battery refers to a ratio between the battery’s capacity and the maximum safe charge current as determined
by each manufacturer for each battery. This value is typically listed in the lower ranges between 1C-5C. It signifies the maximum
current the battery should be charged at in a multiple of the capacity of the battery cells (on a per cell basis, not per pack basis).
» For example: if a battery cell is 2000mAh and the charge C rating is listed at 2C, the maximum charge current that should be
used with this battery is equal to 2000 x 2 = 4000mA = 4.0A.
» NOTE: 1000mAh = 1Ah. For simplified annotation, although charge rates are actually units of Ah, we refer to them as A only.
Thus 1Ah = 1A.
» Since the Primal charger only increments in values of 1A, if the calculated maximum charge rate is a decimal value (4.4) it is
highly recommended to round this value down to the nearest whole number and use that as the
maximum
charge rate, but
not necessarily the
best
charge rate option.
» If the calculated charge rate is over the maximum capability for this charger, you can simply use the maximum allowed.
› Radient RC recommends charging at 1C for the maximum cycle life of your batteries.
› Always check the instructions provided with your batteries for proper charge and care. Those instructions should over-ride these
since they pertain to the particular battery that you have and this is a general statement.
• Discharge Rate Calculation
› The discharge C rating of a battery refers to a ratio between the battery’s capacity and the maximum safe discharge current as
determined by each manufacturer for each battery This value is typically listed in the higher range from 15C upwards. It signifies the
maximum current the battery should be discharged at in a multiple of the capacity of the battery cells (on a per cell basis, not per
pack basis).
» For example: if a battery cell is 2000mAh and the discharge C rating is listed at 30C, the maximum discharge charge current
that should be used with this battery is equal to 2000 x 30 = 60000mA = 60A. This means you can continuously discharge
this battery at a rate of 60A per hour without damage.
» Since the Primal charger does not discharge, this information is only for reference in helping you understand the terminology
of the battery industry.
Termination Voltages (Peak Detection):
• LiPo Batteries: The peak detection of a LiPo battery works by increasing the voltage of the battery pack to a specified range. The goal of the
charger is to increase the voltage of the battery into this range while injecting the most mAh into the battery as possible. The charge cycle
terminates when this value is reached.
› The nominal voltage of a LiPo battery cell is listed at 3.7V.
› The Primal charger will terminate the charge of a LiPo battery pack when it measures a voltage of 4.18-4.2V per cell.
› For a 2s 7.4 nominal voltage battery pack, the termination voltage would be 2 x 4.2 = 8.4V.
• NiXX Batteries
› The nominal voltage of a NiXX battery cell is listed at 1.2V.
› The Primal charger will terminate the charge of a NiXX battery pack when it measures a maximum voltage of the battery pack in a
specified range and then also measures a drop in that voltage of 8mV.
› The maximum voltage a battery pack reaches changes during the life of the battery (increasing with age). The characteristic
behavior of the voltage drop remains the same however thus allowing the charger to continue to detect a “peak” voltage (maximum
voltage - 8mV) regardless of age.
Power Rating (Watt-hour):
› Some products state a recommended Watt hour rating for a battery to be used with that product. The Watt hours can be approxi-
mately calculated knowing the battery capacity and the voltage.
» For Example: if a battery is 2000mAh and the voltage is 8.4V the Watt Hours (Wh) is equal to 2000 x 8.4 = 16,800mWh =
16.8Wh.
Recommended Discharge Voltage Cut-offs:
• For maximum cycle life and safety, LiPo batteries should never be discharged below 3.3V per cell when discharged at a rate of 1-4C. For
this reason, many electronic speed controllers have a special “LiPo Mode” which activates a cut-off of power when the ESC measures the
battery voltage in a dangerous range.
• For maximum cycle life and safety, NiXX batteries should never be discharged below 0.9V per cell when discharged at a rate of 1-4C. The
use of an ESC low voltage “cut-off” mode is not necessary with NiXX batteries.
