This is an excerpt from my Modifications Part 2 that just talks about the Voltage Sensitive Relay I installed one my sled. The relay allows you to charge a second battery while you are running around but then acts as an isolator once the engine is turned off. If you run your accessories, like a Vexilar, off of the second battery you will never drain your starting battery. Another plus is that your Vex battery gets automatically charged. UPDATE: Recommend installing a disconnect or manual breaker between battery and VSR. The VSR is always on and continually drains a small amount of power. It was enough to permanently kill my battery dead this off season.
