2.3 MPPT—Four Charging Stage
Magicube series controller has a 4-stage battery charging algorithm for rapid, efficient, and safe battery
charging.
MPPT Charge
In this stage, the battery voltage has not yet reached boost voltage and 100% of available solar power is
used to recharge the battery.
Boost Charge
When the battery has recharged to the Boost voltage setpoint, constant-voltage regulation is used to
prevent heating and excessive battery gassing. The Boost stage remains 120 minutes and then goes to
Float Charge. Every time when the controller is powered on, if it detects neither over discharged nor
overvoltage, the charging will enter into boost charging stage.
Float Charge
After the Boost voltage stage, the controller will reduce the battery voltage to Float voltage setpoint.
When the battery is fully recharged, there will be no more chemical reactions and all the charge current
transmits into heat and gas at this time. Then the controller reduces the voltage to the floating stage,
charging with a smaller voltage and current. It will reduce the temperature of battery and prevent the
gassing, also charging the battery slightly at the same time. The purpose of Float stage is to offset the
power consumption caused by self consumption and small loads in the whole system, while maintaining
full battery storage capacity.
In Float stage, loads can continue to draw power from the battery. In the event that the system load(s)
exceed the solar charge current, the controller will no longer be able to maintain the battery at the Float
setpoint. Should the battery voltage remains below the boost reconnect charging voltage, the controller
will exit Float stage and return to Bulk charging.
Equalize Charge
Certain types of batteries benefit from periodic equalizing charge, which can stir the electrolyte, balance
battery voltage and complete chemical reaction. Equalizing charge increases the battery voltage, higher
than the standard complement voltage, which gasifies the battery electrolyte. If it detects that the battery
is being over discharged, the solar controller will automatically turn the battery to equalization charging
stage, and the equalization charging will be 120mins. Equalizing charge and boost charge are not carried
out constantly in a full charge process to avoid too much gas precipitation or overheating of battery.
WARNING: Risk of explosion!
Equalizing flooded battery can produce explosive gases, so well ventilation of battery box is
necessary.
U(V)
MPPT
Charge
Boost
Charge
Float
Charge
Equalize
Charge
Night
TIME
13.7V
14.5V
14.8V
Night
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