Battery dilema (not mackintosh computer issue)

I've discovered the battery in my new (s/h) pajero not upto scratch and needs a good charg. The alternator is pumping out 14.75 volts according to my Jaycar multimeter but I would like to remove it from the vehicle and give it a good charge in the garage. I have a newish deepcycle battery that would fit into the vehicle but the question is would it be alright to put it into the vehicle for a week of "mummy going to work" (short runs) or is it beyond the deep cycle capcity?

(nuffin to do with Mackintosh computers)

Thanks in advance.