11
Figure 4-2
Tracer
MPPT charging algorithm
·
Bulk 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, Tracer 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
Tracer 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.