Alpha Technologies AlphaCellTM SMU-C Series - Manual (Page 12)

745-680-B11-001, Rev. A 12
2.1 General Charge
The limited current and constant voltage recharge method, also known as the modified
constant potential method, satisfies the need to have the battery quickly recharged while
ensuring maximum battery life. Figure 2-1 shows the relationship between current, voltage,
and charge for the SMU-C 12-100.
When to Charge
After installing or discharging the battery. •
If the battery has been stored for more than three months and the open circuit voltage is •
lower than 12.6V/block.
General Charge Procedure
Charge the batteries with a constant current no greater than 0.2C 1.
20
A until an average
voltage of 13.8V/block at 77ºF (25ºC) is reached.
Continue charging, reducing the current to maintain a constant voltage of 13.8V/block. 2.
Fast Charge Procedure
Charge the batteries with a constant current no greater than 0.2C 1.
30
A until an average
voltage of 13.8V/block at 77ºF (25ºC) is reached.
Continue charging, reducing the current to maintain a constant voltage of 13.8V/block. 2.
The batteries will be fully charged in 18-24 hours when the voltage is a constant 13.8/ 3.
block and the charge current has not needed adjustment for three continuous hours.
If the heat generated as a result of charging exceeds the rate at which heat can be transferred out
of the battery, thermal runaway can occur and excessive overheating will result.
NOTE:
Take measurements before and after charging and during discharge to help track changes and problems. Use
a form (see Section 6.0), to record the results. Wait two hours after charging before taking final measurements
in order to allow the electrolyte to cool sufficiently.
NOTE:
Refer to your particular charger’s manual for specific instructions regarding charger setup and operation.
Fig. 2-1, Charge Characteristics Curve
(SMU-C 12-100 with initial 0.1C
20
A current and limit voltage 13.8V/Cell)
2.0 Charging Procedures
50%Discharge
100
120
80
20
0.05
60
40
0.25
0.10
0
0.20
0.15
100%Discharge
0
2.33
2.17
2.00
1.83
0 2 4 6 8 10 12
Charge Characteristic
Constant Charge at 25.0A-13.80V (25°C) Charge Capacity (%)
Charge Current (CA)
Charge V
oltage (V/Cell)
Time (Hours)
Charge Voltage
Charge Capacity
Charge Current
CAUTION!