Hey im new here and just wanted to find out some info on my retard car
ok in the last month my car has not been the same i can turn it on and off heaps of times with out the battery going flat but when i take it for a drive to like a petrol station i fill her up then go to start and it seems like the battery is flat so then i have to get some one to come jump start me

lol
but today it did the same thing but at home so i just left it there for a couple of hours while i went and did some work inside and went back out with a multimeter and the batter was at a 100% so i tried to start it and it worked
what i want to no it is seems to do it when the motor is hot

would it have something to do with the starter motor?
when i was looking around the motor and the battery i seen the a couple of the wires that go from the battery to the frame the plastic around it has melted off?

so i was looking at changing all the wires what would be the best wire to do so (0 gauge?) if so were can i get a roll of it for cheap?