I am looking to buy a portable battery charger to keep in my truck in case of emergency. I live in Michigan so it gets pretty cold and I leave my car in drive way for weeks at a time. What is the minimum cold cranking amps I should be looking for? What would be the optimum AMP capacity I should buy? 350? 500? 1000? Any specific make and model you guys would recommend? I was thing about the Stanley J5C09 500-Amp Jump Starter with Built-In Air Compressor http://www.amazon.com/Stanley-J5C09...F8&qid=1388466754&sr=8-1&keywords=stanley+500