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REDARC's BCDC Charging Process Explained

*This article is property of and was originally featured on REDARC. It has been repurposed with permission for use by etrailer.com.

REDARC's BCDC product line features technology designed to charge batteries to 100% regardless of their type or size.

By providing a unique charging profile to each specific battery type, a REDARC in-vehicle battery charger is able to achieve and maintain an optimal charge in an auxiliary battery at all times.

The BCDC automatically senses once the vehicle has started charging the main battery. When the start battery reaches 13.2 volts (26.4 volts on a 24-volt system), the BCDC will then commence charging the auxiliary battery.

Three Stage Charging Process

Boost Stage
Absorption Stage
Float Stage

Image provided by REDARC

The three-stage charging process starts with the ‘boost’ stage, providing maximum current until the battery reaches its predetermined ‘absorption’ voltage. The BCDC will then remain in the absorption stage, holding its set voltage until the unit is 100% charged.

The BCDC then switches to the ‘float’ stage, where it retains the 100% charge. Once the secondary battery voltage falls below 12.7 volts (12 volt) or 25.4 volts (24 volt) due to a large load, the BCDC will recommence the boost stage.

During these charging stages (including float) the BCDC is able to supply loads (up to maximum current output) without necessarily switching back to the boost stage. This protects the battery from overcharging.

The microprocessor constantly monitors the main vehicle battery input charge levels, automatically switching off the BCDC should the main battery fall below 12.7 volts (12 volt) or 25.4 volts (24 volt), so it will not flatten the start battery.

Two Stage Charging Process (Lithium)

Constant Current
Constant Voltage

The BCDC charger works a little differently when used with lithium batteries. When turned on, the charger will move to the Constant Current stage. This stage maintains a constant current until the battery voltage reaches its set point. The current may vary during operation in order to maintain safe operating temperature, or to limit the difference between input and voltage.

The Charger will then move to Constant Voltage stage. This stage maintains 14.5V on the battery output, keeping the battery topped up. When a load is applied to the battery, causing it to lose charge, it will move back into the Constant Current stage.

Image provided by REDARC

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Tom E.

6/17/2022

The article does answer the question of what a DC to DC charger is and how they work. Good article.

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