Installed in a car with parasitic battery discharge. I checked that the battery is well charged and has a voltage of more than 12.4 volts. I installed this device according to the instructions and in a specific critical order. After waiting two months to finally check my car. Nothing - dead battery, dead truck. WOW what a false promise that was. Of course, the time it takes to see if it works means you've exceeded the return period. So I have $100 plus a unit of JUNK! I would NOT recommend this at all. I feel like an idiot buying this. I'm sure you can ask a lot of questions - is the battery dead - is the truck in a vortex electromagnetic energy field - is there some other reason that could have caused this that I'm not considering? All excuses to explain why it's on the market and still selling. The answer is simple - I don't know - but I know it's a waste of money now that I actually work for. I know this device may be a rare bug that you won't experience when you buy it. Whatever it takes for a person to justify a purchase and feel right about their decision, just remember I've been there too. I figured I'd survive the risk and succeed. I didn't - I DID NOT pass - will you be next? Add to cart and find out.