I use a battery master switch, but I use it more for when I go to car shows and cruise nights so I can leave the doors open and not worry about the lights killing the battery. It is bad for the battery to constantly kill it and charge it. This is called deep cycling and it shortens the battery's life sigificantly. It is even worse in cold weather because a dead battery can freeze and warp the plates inside ruining the battery. In storage the battery should be removed and kept in a warm place on a piece of wood and trickle charged once a month for 1 day. BTW if you use a battery master switch unless you bypass it for the radio you will always lose the time and the preset stations. David Teitelbaum vin 10757 --- In dmcnews@xxxxxxxxxxxxxxx, "spaceace3113" <spaceace3113@xxxx> wrote: > Does anyone use them on their cars? If so what type and from where. > I take my car out infrequently and almost always have to boost it.