I've been using my Sullivan starter with a Hobbico battery pack for a few years now and have had no trouble with it whatever. At first I was concerned about the weight of the pack hanging underneath the starter (see the ad pictures in Tower) but it's not too heavy, and surprisingly enough I find it adds a bit of balance to the starter. Besides once the engine starts you're gonna set it down anyway. By the time you need it again you'll be back up to strength! Nice not to have any wires to hook up and fiddle with.