Outback Power Systems FLEXmax Extreme Owners Manual - Manual (Page 74)

Applications
72 900-0150-01-00 Rev A
Float stage. The charger will also also exit Absorbing if the Absorb End Amps setting is reached, regardless of
the timer. This resets the timer to zero. (See page 36.) This stage is temperature compensated.
Float
This is the third stage of charging. It is a constant-voltage stage. The batteries are maintained at the Float set
point. This stage is not timed. The FLEXmax Extreme will continue to maintain Float as long as PV energy is
available. Current varies as needed to maintain the voltage, but typically drops to a low number.
If the PV cannot supply enough power to maintain the Float set point, the FLEXmax Extreme will not
immediately initiate a new charge cycle. It will attempt to draw more PV energy and recharge the battery until
the Float voltage set point is reached. This stage is temperature compensated. (See page 72.)
A new charge cycle can be initiated if the voltage falls below the ReBulk set point for 90 seconds or more (see
page 36).
Equalize
Equalization is a controlled overcharge that is part of regular battery maintenance. Equalization follows the
same pattern as standard three-stage charging. However, it brings the batteries to a much higher voltage and
maintains this voltage for a period of time. This has the result of removing inert compounds from the battery
plates and reducing stratification in the electrolyte.
The set points for equalization are adjustable with the MATE3 system display. See page 38.
CAUTION: Battery Damage
 Do not equalize any sealed battery types (VRLA, AGM, Gel, or other) unless approved by the
manufacturer. Some batteries may suffer severe damage from equalization.
 Contact the battery manufacturer for recommendations on equalization voltage, duration,
schedule, and/or advisability. Always follow manufacturer recommendations for equalization.
Equalization is normally performed only on flooded lead-acid batteries. The schedule for equalization varies
with battery use and type, but it is usually performed every few months. If performed correctly, this process can
extend battery life by a considerable amount.
Equalization can be triggered manually. To trigger equalization, press the EQ button located on the front of the
charge controller. (See page 6.) Hold this button for 5 to 10 seconds, then release. Once triggered, the Status
indicator begins alternating amber and green once per second. If the batteries are below 1.75 Vpc, the Status
indicator will alternate amber and red. (See page 23.)
Equalization can also be triggered on an automatic schedule. The settings for this schedule are adjustable with
the MATE3 system display. See page 38.
Battery Temperature Compensation
Battery performance changes when the temperature varies above or below room temperature (77°F or 25°C).
Temperature compensation is a process that adjusts charging to correct for these changes.
When a battery is cooler than room temperature, its internal resistance goes up and the battery voltage changes
more quickly. This makes it easier for the charger to reach its voltage set points. However, while accomplishing
this process, the charger will not deliver all the current that the battery requires. As a result, the battery will tend
to be undercharged.
Conversely, when a battery is warmer than room temperature, its internal resistance goes down and the voltage
changes more slowly. This makes it harder for the charger to reach its voltage set points. It will continue to
deliver energy as time passes until the charging set points are reached. However, this tends to be far more than
the battery requires, meaning it will tend to be overcharged.