SamplexPower SAM Series, Owner'S Manual

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10 | SAMLEX AMERICA INC.
2.5.2 2 Stage charging - Bulk charge and float charge Stages
The built-in battery Charger is a "2 stage charger".
Working of a 2 Stage Charger is explained below. Please refer to Fig 2.3.
Bulk Charge
Stage
Float Charge
Stage
Charger Current Curve
Charger Voltage Curve
Time
V
oltage
C
urr
en
t
9
10
11
12
13
14
1
1
2
2
3
3
15A
0A
LEGEND
1. Charging Starts
1 to 2. Bulk Charge Stage: Constant Current = 15A
2.
Exits Bulk & enters Float
2 to 3. Foat Stage: Constant Voltage = 13.8V
Current tapers to 0.25% of Ah Capacity
13.8V
5A
10A
20A
Fig. 2.3 Battery Charger Stages and Voltage/Current Curves
2 Stages of Charging are (i) Constant current Bulk Stage and (ii) Constant voltage Float
Stage. A 2-Stage Charger is able to recharge a battery to around 80% capacity. This type
of charger is used in backup / UPS applications where the battery remains charged, is
floating most of the times and will discharge at lesser frequency only during power out
-
ages. Charging details are given below:
i. The charger outputs a constant, regulated voltage of 13.8V (Float Charge Stage
Voltage) and can deliver up to 15A of maximum charging current (Bulk Charge Stage
Current). If the battery tries to draw current higher than 15A due to its discharged
condition, the charger enters Current Limit Condition. Under Current Limit Condition,
the charger will supply constant current of 15A, its output voltage will no longer be
regulated and will drop below 13.8V. However, its output voltage will get clamped to
the battery voltage corresponding to the State of Charge of the battery.
ii. The input resistance of a healthy battery is very low – around 16 milli ohm at com-
pletely discharged condition to less than 8 milli ohm when fully charged
SeCTIOn 2 | Features, Applications &
Principle of Operation