I'm using a legacy cigarette lighter socket and a separate 2x2.4A USB charger. That is because a cigarette lighter socket is nearly unbreakable being very simple and it somewhat tolerates water, no fancy electronics in it. USB chargers might not be that long lasting (having more components), a separate charger is easy to replace and it's easy to unplug (it consumes some power by itself). The other thing is that in the winter time I do not unplug the battery but every now and then connect the CTEK smart charger to the cig lighter socket. A cig lighter socket also enables you to connect any other compatible device and there are plenty.