RE: discharging batteries
This will work for a while. I used that method for quite awhile when running cars. But I would invest in a descent charger that will cycle your batteries for you. Keeps them healthy and the charger will pay for itself in the long run. (45 dollars a crack for good batteries). As far as what charger to use! I use the triton have had no problems. Recommend seeing the batteries and charger section on this site for a better look at what to buy!
Hope this helps