[Al Skierkiewicz]

To clear up a few misconceptions...
Although one would think that connecting batteries this way should be possible, it is not. No battery has exactly the same terminal voltage as another battery, even fully charged batteries of the same type and manufacture. When two batteries are connected in parallel the slightly higher voltage battery will try to supply current to the lower voltage battery until it becomes the lower voltage and the the second battery will try to supply current to the first. Around and around the current goes until both batteries are dead and you haven't even connected it to anything yet. (It takes a while but it does happen)
Add a third battery and a fourth and the same thing occurs with more permutations.
The correct way to connect batteries (in parallel) for greater current is to use power diodes in series with the positive lead. If you can't stand the voltage drop of a power diode you can use a power Schottky diode which has a lower junction voltage. Connect the anode of each diode to the positive battery lead and then connect the cathodes of all the diodes in parallel.
As you have noticed, the more current capability the more dangerous shorts become. Have you ever seen a 1/4" open end wrench go incandescent?
For safety, the terminals of all batteries need to be insulated at all times and the output of the diode connection needs to be protected with a circuit breaker or fuse.
These batteries, even in single quantity, are capable of very high current, and if mishandled can result in fire, damage to battery and possible explosion hazard. It is essential to know the dangers of battery misuse. If you have a question just ask, I will get back to you.