If nobody else want to guess... I will.
Legally, with all the paperwork, cut-off switch, special meters, fees for special meters, etc, payback could be 100,000,000 years.
IIRC, that is UL listed and legal to connect, AFTER all the hoops are jumped through.
('gorilla' is a lot less appealing than it once was)
IIRC, they did not have the best track record as far as useful life expectancy.
Trace went through all the effort and cost to get it UL stickered, then stopped making it, Why?
There was a time when it was easier to find online requests about repairing one than buying one.
(it may not function)
More useful data would be found online using the European brand name.
If it was a vote, mine would be use the 120W for the battery.
G-