I have made up my mind that I will be using a circuit breaker in my transpack to offer safety and the ability to cut the power to the rest of the system. I may also purchase some semiconductor fuses in the 1000 to 1500 amp rating for extra safety. I purchased a Cutler hammer HMCP250W5 circuit breaker, which is rated at 250 amp continuous. It is a 3 pole motor circuit breaker that will work with up to 250Vdc, and has an instantaneous trip rating of no higher than 1750 amps when using it in DC. I will use the two outside poles, as the breaker suggests, and put it inline of the positive and negative wires of my trans pack. I still have not decided if I want to put it in the center of my trans pack, so there are 3 48 volt blocks of batteries, or put it on the main leads going into the pack, so there would be a 144 volt block of batteries. I will probably put it in the center.
The contactor that I plan to use is Tyco Electronics Kilovac p/n: EV200HAANA. It has a reasonable price, and proper specifications for what I will be needing.