CTEK's D250SE battery charger unboxed 

David and Steane take a close look at CTEK's D250SE 20amp DC-DC battery charger.
The D250SE will work effectively with a smart alternator, it’s just a matter of connecting the red and black smart alternator cables that exit the right side of the unit as directed in the instructions, black to earth and red to an ignition signal.
The D250SE charger also has a solar input so that you can add some solar charging to your system, and it can be used in tandem with a CTEK SMARTPASS 120S to more effectively charge larger (300Ah+) auxiliary batteries.
Not only will the D250SE charge wet cell, AGM, gel cell and calcium batteries, it will also charge the increasingly popular lithium LiFePO4 battery types, and that is essentially what separates the D250SE from the D250SA that it has replaced on the market.