MK4+ Hybrid Charge Controller User Manual
3
Constant-Current and Constant-Voltage Charge Mode:
A charging battery normally falls into one of two states. When a battery is
significantly discharged it can initially accept all the current the wind generator
can supply it with. In this state, we refer to the charging profile
as the “bulk”
stage, or constant-current mode, of charging. When operating in the bulk
phase, the battery is accepting the maximum current, which allows its terminal
voltage to increase as it accepts the charge. When the battery reaches about
75% of full charge,
the controller begins the “absorption” stage, or
constant-voltage mode, of charging. In the absorption stage, the maximum
charging voltage is now limited by the controller, and the charging current
begins to naturally fall off as the battery continues to charge. The MK4+ is
unique in its ability to vary the amount of energy that is supplied to the batteries
in order to reach a full state-of-charge and avoid damage from overcharging.
In a sustained high-velocity wind, when the MK4+ charging current exceeds its
maximum current set-point, the controller will automatically begin to brake the
wind generator (slow or stop the blades) to protect the controller and the
generator windings from excess current and heat. In this over-current
condition, the brake will automatically remain applied for 10-15 minutes to
protect the wind generator and controller from overheating. In addition,
should the battery voltage exceed its over-limit shutoff voltage, the controller
will automatically brake, slowing or stopping the blades. The braking mode
may also be deployed manually at any time by the user by using the manual
