Generally speaking. The trickle charger is the best thing for your batteries however, u need to get one suited to the type of battery you have in your car. Lead acid batteries are the everyday batteries that u can "top up" and they would be the easiest to maintain but every now and again need to be checked for fluid levels and the calcium/calcuim batteries which are commonly referred to as maintainence free batteries. These batteries require a different charger so they dont over charge. 14.1V is a recommended voltage for these.