SoLucky is so right.....
I was thinking about adding a pig-tail onto the batterry that lays neatly in the trunk,with male/female receptical ends so it is convenient to recharge on a regular basis.
Just check battery capacity (both volts and % charge) using jumper points under hood and even a new battery can be below 12V and low 50% capacity.
Will be interested if the battery is the issue.
Good luck... it's the easy solution... if it is the solution.