VICTRON ENERGY CYR010120412, is an intelligent voltage controlled isolating relay (battery combiner) including cabling, cable ties and ring cable lugs.
Cyrix battery combiner is a microprocessor-controlled powerful relay that automatically connects batteries in parallel connection when one of them has reached a preset voltage (indicating that the battery is charging) and breaks when the voltage drops a floating level (indicating that one or several batteries discharge). Cyrix battery combiners are an excellent alternative to diode isolators. The most important feature is that there are virtually no voltage drops so the output voltage from generators or battery chargers does not need to be increased.
In a typical installation, the alternator is connected directly to the starter battery. The consumption battery and possibly a bow battery or other battery, are each connected to the starter battery with a Cyrix battery combiner. When a Cyrix senses that the starter battery has reached the junction voltage, it ensures that the others are charged in parallel.
Good product related links: