We used two auto batteries with the Dynatron and if you kept the engine rolling over for any length of time the starter would start getting hot to the touch. If we just burped it on and off it was fine. I have loaned out my starter with that HF 18 volt to people and if they keep it rolling over too long it will get hot. When I loan it out I make sure to tell them how to use it or the switch can get fried.
I didn't know that Sullivan didn't have a complete warranty on that starter. My friend that bought the Dynatron is now fully electric so when I see him this year I may be able to get whatever old gear he still has, I hope the Dynatron is still with him!! That's one stout starter.