Use this for a truck I only drive every 2-3 weeks, have the clamps run straight to the battery and haven't had an issue in almost a year since I added it. Can't speak to what kind of voltage it's actually putting out but wouldn't imagine it's adding enough juice to be a problem and doesn't need to be plugged in so no cords all over the place.
https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1