Section 6: Multistage Charging

The Prosine inverter/charger has a fully functional multistage battery charger. Any time an acceptable (within frequency and voltage parameters) AC source is presented to the unit, it will charge the batteries connected to it. When AC is present and the charger is enabled, the charger will charge the battery bank regardless of the position of the inverter’s On/Off switch.

Charging Profile

The battery charger in the Prosine charges in three stages—BULK, ABSORPTION, and FLOAT— to provide rapid and complete charge cycles without undue battery gassing. The figure below shows how DC voltage and current change with time through the different charge stages.

 

 

 

 

 

 

 

 

 

Bulk

Absorption Charge

 

Float Charge
ChargingBulk Volts Setting

 

 

 

Started

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Float Volts Setting

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

DC Voltage

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Constant Current

 

 

 

 

 

 

 

 

 

 

 

 

 

@ Maximum

 

 

Reduced Voltage

 

 

 

 

 

 

 

 

 

Charge Rate

 

 

 

 

 

 

 

 

 

 

 

 

 

Load current on demand

 

 

 

 

 

 

 

 

 

 

 

 

Constant Voltage

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

DC Current

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TimeFigure 7. Three-Stage Charging Profile
Bulk Charge

In the first step, known as the bulk charge, the Prosine inverter/charger delivers the maximum charge current allowable given the configuration settings, that is, battery type and temperature, maximum AC input setting and battery bank size. This current is delivered to the batteries until the battery voltage approaches its gassing voltage—typically around 14.4 volts for 12 volt batteries and 28.8 volts for 24 volt batteries (again this voltage can vary depending on battery type and other settings). The bulk charge step restores about 75% of the battery's charge. The gassing voltage is the voltage at which the electrolyte in the battery begins to break down into hydrogen and oxygen gases. Under normal circumstances, a battery should not be charged at a voltage above its gassing voltage since this will cause the battery to lose electrolyte and dry out over time. Therefore the Prosine inverter/charger transfers to the next stage, known as the absorption charge.

Absorption Charge

During the absorption charge, the charging voltage is held constant near the gassing voltage and the charging current is steadily decreased. When the charging current has decreased to a predetermined

Prosine 2.5/3.0 Installation & Operation Guide

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