Review on Xantrex C40 Charge Controller by Max Rosengren

With enough power from our charger, the C40 keeps the battery charged to a few tenths of a volt. The application is a backup power system on a remote amateur radio repeater. We have two 200Ah batteries charging from a 70A DC source. The D-Star repeater system connects directly to the batteries. AC power for the computer and accessories is provided by a Xantrex sine wave inverter, which is also connected to batteries. The C40 is set to ramp the battery down to 14.5V and then slowly let it drop to 13.5V. These are the values recommended by the battery manufacturer. As stated in the manual, the green LED on the C40 will flash when the battery voltage falls below the float level. The number of flashes in the sequence tells us where the C40 is in its loading sequence. When charging is complete, the LED will be solid.