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SECTION 5 | Battery Charging in Evolution™ Series
The value of the "BULK CURRENT" (“Io”) depends upon the total Ampere Hour (Ah) capacity of the battery or bank of
batteries. A battery should never be charged at very high charging current as very high rate of charging will not return the
full 100 percent capacity as the Gassing Voltage rises with higher charging current. As a general Rule of Thumb, the
BULK CURRENT “Io” for Lead Acid Batteries should be limited to 10% to 20% of the Ah capacity of the battery
[Ah capacity at C-rate of discharge = C/20 (or, 0.05C)]. Higher charging current may be used for Lead Acid Batteries if
permitted by the battery manufacturer. Lithium Ion & Nickel Zinc batteries may be charged at higher rates of up to 50%
to 100% of their Ah capacity.
Programming range and Default values of "BULK CURRENT" (“Io”) are shown in Table 6.2 and also at Table 4.3 under
Section 4.4.1 of EVO-RC-PLUS Remote Control Manual. The units are shipped with the "BULK CURRENT" set at the
Default Value of 20A. For programming information for this parameter, please refer to Section 4.4.2.1 of EVO-RC-PLUS
Remote Control Manual.
When the unit enters Charging Mode, it starts working as a battery charger and the charger will ramp up to full
programmed "BULK CURRENT" until the charger reaches the programmed threshold of "ABSORP VOLTAGE".
NOTE: The charging current will slowly ramp up to the programmed value of BULK CURRENT.
For Adaptive Charging Prole Option "0=3 Stage Type 0" (See Srl. No. 1 in Table 5.2), a software timer will measure
the time taken from the instant the unit enters the Bulk Charging Stage until the instant the battery voltage reaches
0.3V below the programmed "ABSORP VOLTAGE", then registers this time as Bulk Charge Time "To" and computes
Absorption Time "T1" as 10 times the Bulk Charge Time "To" in the internal “T1 Timer” i.e. T1 = To x 10 (Minimum
value of "T1" is 1 Hr and max value is 12 Hrs). The “T1 Timer” is used to determine the time the charging will take
place in the next Absorption Stage (Section 5.7.2).
5.7.1.2 Automatic Adjustments of Internal AC Charger Current When External Solar Charge Controller is
Also Charging in Parallel
Please note that if an external Solar Charge Controller is also used to charge the batteries at the same time in parallel
with the internal AC charger of the unit, the charging current of the internal AC charger will be controlled so that the
total charging current of the external Solar Charge Controller and the internal charger is = the programmed "BULK
CURRENT (“Io”).
For example, if the programmed "BULK CURRENT (“Io”) is say 40A and the charging current of the external Solar
Charge Controller is 30A, the internal AC charger will output only 10A (Programmed setting of 40A – external charging
current of 30A = 10A). Similarly, if the programmed setting is say 30A and the current supplied by the external Solar
Charge Controller is say 50A, the internal AC charger will NOT provide any charging current.
Please refer to Section 5.4 for more details.
5.7.2 STAGE 2 – Absorption Stage
During the Absorption Stage, the Duty Cycle of the boosted high frequency PWM voltage pulses (Section 5.1.2) is adjusted
continuously to keep the battery at constant voltage (CV) = the programmed value of parameter "ABSORP VOLTAGE"
to ensure that the battery is further charged to the full capacity without overcharging. Programming range and Default
values of "ABSORP VOLTAGE" are shown in Table 6.2. Default value is 14.4V for EVO-1212F / EVO-1212F-HW and 28.8V
for EVO-1224F / EVO-1224F-HW. For programming details of parameter "ABSORP VOLTAGE", refer to Section 4.4.2.2
of the EVO-RC-PLUS manual. The Absorption Stage restores the remaining 25% of the battery’s charge. The time the
charger remains in the Absorption Stage is proportional to the depth of discharge of the battery. When the battery is
more discharged, it will take longer time in the Bulk Charge Stage to reach the Gassing / Absorption Voltage.
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