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3. Operation
3.1 Multi-stage charge algorithm
The Victron
Blue Smart Charger
range are intelligent multi-stage battery chargers, specifically
engineered to optimise each recharge cycle and charge maintenance over extended periods.
The multi-stage charge algorithm includes the individual charge stages described below:
1. Bulk
The battery is charged at maximum charge current until the voltage increases to the configured
absorption voltage.
The bulk stage duration is dependent on the battery’s level of discharge, the battery capacity and
the charge current.
Once the bulk stage is complete, the battery will be approximately 80% charged (or >95% for Li-
ion batteries) and may be returned into service if required.
2. Absorption
The battery is charged at the configured absorption voltage, with the charge current slowly
decreasing as the battery approaches full charge.
The absorption stage duration is adaptive and intelligently varied depending on the battery’s level
of discharge – this is determined from the duration of the bulk charge stage.
The absorption stage duration can vary between a minimum of 30 minutes, up to a maximum
limit of 8 hours (or as configured) for a deeply discharged battery.
3. Recondition
The battery is charged at low current until the voltage increases to the configured recondition
voltage.
Recondition is an optional charge stage for lead acid batteries and not recommended for
regular/cyclic use - use only if required, as unnecessary or overuse will reduce battery life due to
excessive gassing.
The higher charge voltage during recondition stage can partially recover/reverse battery
degradation due to sulfation, typically caused by inadequate charging or if the battery is left in a
deeply discharged state for an extended period (if performed in time).
The recondition stage may also be applied to flooded batteries occasionally to equalise individual
cell voltages and prevent acid stratification.
During recondition stage the charge current is limited to 8% of the nominal charge current, (for
example - 1.2A for a 15A charger) and the stage is terminated as soon as the battery voltage
increases to the configured recondition voltage or after a maximum duration of 1 hour (or as
configured).
4. Float
The battery voltage is maintained at the configured float voltage to prevent discharge.
Once float stage is commenced the battery is fully charged and ready for use.
The float stage duration is also adaptive and varied between 4 to 8 hours depending on the
duration of the absorption charge stage, at which point the charger determines the battery to be
in storage stage.
