Xantrex Technology 10 - Manual (Page 51)

Battery Charging
975-0251-01-01 3–13
The battery charger stages are:
• Stage 1—Bulk Charge. During the bulk charge stage most of the charge
current is delivered to the battery bank. This phase is engaged as soon as the
battery charger is activated. Full rated charger current is delivered to the
battery bank until the bulk charge voltage limit is reached. This results in a
relatively rapid recharge.
It is generally agreed that a wet cell battery bank should not be charged up to
the gassing point at a rate that exceeds 25% of its capacity. In other words, a
12-volt battery bank of 520 amp hours should not be charged at over
130 amps.
Gel cell batteries can accept a higher rate of charge. Consult the manufacturer
for details.
• Stage 2—Acceptance Charge. The acceptance stage immediately follows the
bulk charge stage. During this stage, the battery voltage is held constant at the
bulk charge voltage limit and the current gradually ramps down. During this
stage the battery is accepting its final amount of charge current and the last of
the sulfate on the plates is removed.
The acceptance stage lasts until the charge current reaches about 6 to 7 amps
(3 to 4 amps for a 24-volt system). A timer will terminate the acceptance stage
if this current level is not reached. This timer is set automatically when the
DIP switches for battery type are set. Maximum acceptance time is 1 hour for
wet cells and 3 hours for gel cells. Gel cell acceptance time can be increased
because the battery is not gassing. Expect wet cell batteries to gas somewhat
during acceptance. This is a necessary part of the charging process.
Figure 3-7 Benefits of the Freedom Charger vs. the Traditional Taper Charger
"Bulk Charge"
Constant Current
"Acceptance Charge"
Constant Voltage
Finish "Float"
Charge
Equalizing
100 Amp
Taper Charger
Freedom
Charger
Traditional
Charger
11 12 13 14 15 16
50
40
30
20
10
Quicker, more complete recharging, safe long-term charging
and battery rejuvenation through an equalizing charge.
Amps
Volts