The shop I went to kinda made it sound like it wasn't worthwhile. I'm not really in need of one that small so I think he told me he could get me a true 90 amp or bigger for around 90.00 so that's what I will do over the Winter. That way he can verify it while I'm standing there. My small tire car came with a 16 volt but for now it will be going back to 12 volt. Back to back testing on my car years ago showed me that wasn't needed and I didn't even have an alternator on that car.