purchased a generator from amazon.com it was a Duramax 4400e with a battery start option, after 3 years the battery was not charging any longer, so I tried to replace it no such luck the Duramax company had a patent on the battery and nobody else was selling this type of battery. My next try was to call Duramax to get this battery no luck they never did get the battery in stock in stock stock stockdo for medo not User's recommendation: do not buy there products.