Samlex America SEC-2425UL - Manuel (Page 8)

8 | SAMLEX AMERICA INC.
seCtIOn 4 | Principle of Operation
For example, when SEC-1250UL is in the Bulk Charge Stage 1, its output voltage is set
at 13.5 VDC. When a battery discharged to say 10.5V is charged, it will try to draw very
large current = (13.5V - 10.5V) ÷ Internal resistance (0.02 Ω) = 150A. SEC-1250UL will,
however, limit this current to 50A.
cHARGinG StAGeS
The battery is charged in 3 stages:
• STAGE 1 -BULK STAGE (“I” Phase),
• STAGE 2 - ABSORPTION STAGE (“U
o
” Phase) and
• STAGE 3 - FLOAT STAGE (“U” Phase)
The 3 charging stages and associated Charging Curves for SEC-1250UL are given at Fig-
ure 4.1 and for SeC-2425UL at fig. 4.2
Figure 4.1 Charging Curve - SEC-1250UL
* Stage 2 time for 4 or 8 hours.
Voltage
curve
Current
curve
10% of
current
capacity
of charger
(5A ± 0.5A)
80% of
current
capacity
of charger
(40 Amps)
Time, Hours
14.4V
13.5V
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
55
50
45
40
35
30
25
20
15
10
5
0
AMPS VOLTS
Fig xxx - SEC-1250UL Charging Curves (Absorption 14.4V, Float 13.5V)
50A
Stage 1
“I Phase”
Stage 2*
“Uo Phase”
Stage 3
“U Phase”
B1 C1
D1
E1
B2 C2 D2
E2
A1
A2