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c) Using Adaptive Charging Algorithm: This ensures that the battery is completely charged in a safe manner
for longer battery life (Suitable for battery that does not have load connected to it). In this algorithm, the time
the battery remains in Absorption and Equalization Stages is automatically made proportional to the time the
battery remains in the Bulk Charge Stage. A battery that is deeply discharged will remain in Bulk Stage for a
longer duration and will require longer time in the Absorption and Equalization Stages for complete charging.
On the other hand, a battery that is almost completely charged will remain in the Bulk Stage for a shorter
duration and consequently, will remain in Absorption and Equalization stages for a shorter duration. This will
prevent overcharging / boiling of the battery. EVO Series has 2 programmable options to use this Adaptive
Charging Algorithm – (i) 3-Stage Adaptive (Table 5.2, Srl. 1) & (ii) 4-Stage Adaptive for Equalization (Section
5.8).
1.4.3.3 Stage 3 - Constant Voltage Float Stage: The Float Stage is a maintenance stage in which the output
voltage is reduced to a constant lower level, typically about 13.5 V for a 12 V battery and 27 V for a 24V battery to
maintain the battery's charge without losing electrolyte through gassing and also, to compensate for self discharge.
Self discharge of Lead Acid Battery is the electrical Ampere Hour (Ah) capacity that is lost when the battery is not
being charged and there is no load connected to it. i.e. sits idle in storage. Self-discharge is caused by electro-chemical
processes within the battery and is equivalent to application of a small electrical load. For example, Lead Acid battery
stored at 30°C / 86°F would self-discharge at around 1% of remaining capacity every day. Self-discharge increases
with increase in temperature. Self-discharge of the battery under long term storage will create condition equivalent to
under charging and consequently, lead to “sulfation” as explained at Section 1.4.4.1.
1.4.3.4 Stage 4 - Constant Voltage Equalization Stage: This stage is normally initiated manually because it is
not required every time the battery is recharged [In EVO, it is carried out manually through programming parameter
"EQUALIZE-4STAGES"(See Section 4.4.2.12 in EVO-RC-PLUS Remote Control Manual)]. Normally, only vented / wet cell
/ ooded batteries are equalized. Some sealed AGM batteries may be equalized if recommended by the manufacturer
(e.g. Life Line brand of sealed, AGM batteries). Equalization Stage is normally activated after completion of the Bulk
and Absorption Stages. During the Equalization Stage, the battery is intentionally charged at a constant voltage at a
value above the Gassing Voltage which is normally in the region of 2.5 to 2.7 V per cell at 25º C / 77º F (e.g. 15 to
16 V for 12 V batteries and 30 to 32 V for 24 V batteries). The time the battery remains in this stage is determined as
follows:
• By a xed timer (e.g. 4 to 8 Hours): This may result in overcharging of almost fully charged batteries
• Using an automatic Adaptive Charging Algorithm: This ensures that the battery is equalized in a safe
manner for longer battery life. EVO Inverter Charger Series uses this Adaptive Charging Algorithm for
Equalization. [Refer to Section 1.4.3.2 (c) for details.]
Recommendations of the battery manufacturer are to be followed for equalizing the batteries as the equalization
voltage, current, time and frequency will depend upon the specic design of the battery. As a guide, a heavily used
ooded battery may need to be equalized once per month and a battery in light duty service, every two to four months.
The Equalization Charge Current should be a relatively low current of around 2% to 10% of the Ah capacity of the
battery. Such a low current prevents an overcharge condition that results in excessive gassing and excessive loss of water.
1.4.4 Why Flooded / Wet Cell Lead Acid Batteries Are Equalized?
For proper health and long life of a Lead Acid battery, it is required to undergo an Equalization Stage (described at
Section 1.4.3.4 above) during the charging process to prevent / reduce the following undesirable effects:
SECTION 1.4 | General Information – Battery Related
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