The Cyrix battery combiner is a microprocessor-controlled heavy-duty relay that automatically connects batteries in parallel when one of them reaches the preset voltage (indicating that the battery is charging) and disconnects when the voltage drops below the float level (indicating that one or more batteries are low). Cyrix battery combiners are an excellent replacement for diode isolators. The main feature is that there is no voltage drop. Therefore the output voltage of alternators or battery chargers does not need to be increased.