Instruct: Classify an Amazon review as either positive or negative.
Query: Works perfectly

My SUV has an always-on plug in the back, and I use it to plug in my Koolatron 12V Travel Cooler (D24).But since it is always-on, I would need to unplug it when I stopped for any length of time to ensure my battery would not be drained.This is where the Koolatron Battery Saver comes in. It plugs into my vehicles outlet, and then the cooler is plugged into it.It will continue to provide power to my cooler until it detects that my battery is starting to lose power (around 11 volts) and then it will kill the power to the cooler.Now I can just leave the cooler plugged in all the time, and I don't worry about running down my battery.Great product, and works exactly as described for me.