Originally Posted by TonimusMaximus
+1 on the LiPo batteries. WAY smaller and lighter. Really robust too. You could put two LiPo batteries in a fire bag for less than the cost of a decent deep cycle. Two 7.4 volt LiPos in series will start my truck no problem. 5.2 amp hour, 14.8v nominal, about $45.
Why not get like a proper tongue box from Harbor Freight? They're cheap, light, and designed for this.
When you say two 7.4 batteries will START your truck "no problem", are you saying they will start your truck ALONE, or are you just using them to give your regular battery a quick boost? Because those two small batteries would have to produce some 400 cold cranking amps of power during the time you are cranking your engine.