I have to admit i have not put them in my car yet cuz im testing them out for battery life and to see if they crap out which they havent and i set these on my speakers that play music when i go to sleep at night so the vibration keeps them on all night long two nights in a row now about 8 hours each plus during the day well i use them for coasters for cups coffee mugs etc and still the batteries of not going dead they light up every time as stated when i place something on them theyre nice and bright a good bright though in the dark while watching tv and using them its not a blinding light