Have you read their warranty?
It looks like they have included every possible way to get out of covering
the battery by things like operating temperatures, type of cleaners used on the battery casing, decrease in charge retention capacity before the warranty period expires (what's with that???) etc.
I would be very suspicious until I see more test data from actual use, not the manufacturer. As stated above, they do not specify their waiting times between recharging, which is key to preventing sulfating in any lead based battery system.
Be careful out there!!!