An automotive charger is far to powerful, depending on what the "maintain" setting was a person could maybe use that as it is usually a trickle setting charging at a very low amperage respectively. But I couldn't condone it.
I would recommend investing in a balance charger, that way a person could charge various battery types and cell counts. Much safer too.
http://www.amazon.com/dp/B005EF15Q4...UTF8&colid=995CBEQ0QFBT&coliid=I3AT7T9XME7556
Would need to either purchase the laptop power supply in the "frequently bought together" or a better option would be to "hack" a power supply of a desktop computer so that it will run, not hooked to a computer. These power supplies have more juice available and can handle larger loads, as well as have a built in cooling fan. I use the B6 linked above, but I have yet to set up the desktop PS, just running on the laptop charger right now, it gets pretty warm at times.
Or if you really don't see yourself getting lipo/multiple battery's and just sticking with what you have, a wall charger would do just fine.
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXL342 (not sure what connection you have, just an example)
But if you upgrade your motor/esc I see lipo's in the very near future.
Edit:
Wait, I'm confused, is this unit in question for charging automotive batteries?
Or is it a charger that hooks to an automotive battery to charge smaller batteries?
Two very different things.