Here is a bit of a description of the Redarc
Product Description
The BCDC1240-LV is a 12V 40A In-vehicle Battery Charger featuring technology designed to charge your batteries to 100%, regardless of their type or size. By providing a unique charging profile to each specific battery type, the BCDC1240-LV In-Vehicle Battery Charger is able to achieve and maintain an optimal charge in your auxiliary battery, at all times. It is designed to operate with variable voltage alternators.
The BCDC1240-LV In-vehicle Battery Charger also features a Maximum Power Point Tracking (MPPT) solar regulator, allowing you to deliver the maximum amount of power from your solar panels to your auxiliary battery.
Features
Multi Stage DC-DC Battery Charger
MPPT Solar Regulator
Start Battery Isolator
Fully sealed
Super quiet operation
Charges AGM, Gel, Calcium content, VRLA and Standard Lead Acid batteries