The Ironman 140 Amp Dual Battery Kit allows two batteries to be charged at the same time. When the engine is started and the main battery reaches 13.4 volts, the Ironman module engages, allowing the two batteries to be charged simultaneously.
When the voltage drops below 12.8 volts (e.g. the engine is stopped), the Ironman module disengages, isolating the batteries.
The Ironman dual battery monitor displays the voltage levels of both batteries. The Ironman 140 Amp Dual Battery Kit eliminates the possibility of draining the starting battery, as long as your accessories are connected to your auxiliary battery.