what's wrong with the Honda? can it be repaired?
3/4 acre, I'd probably stay with ICE.
I do have batteries that are 9 years old, but I can't imagine them lasting 3X that. They are pricey, but you should consider them prepurchased fuel. Then they don't seem pricey.
As for the rest of the...
Do the problems coincide with any change in the ac supply outlet? Have you tried a different outlet? Just wondering if a hot/neutral reversal at the outlet would cause anything like this.
There may be a guy on ebay that works on that stuff.