GPS car adapter question?

[Dongotto]

I can get a car/boat charger for my Garmin Map76s. My question is will it power the unit without batteries, or if the batteries are dead?

[chodie1]

I have a garmin 76cx and I also have the plug in adapter. It will power the unit with or without batteries in it, but will not charge batteries. I found that the unit uses up the batteries real fast, so I bought the adapter. Works great this way.