There’s lots of really smart people out there whose capabilities are wasted and I suspect the guy who friend requested you is one of them. The perpetual motion people always overlook one or two important things as to why it won’t work but otherwise, their stuff often checks out. So I could see how they get hooked on their own theories. Plus, with no one to contradict them…
From a pragmatic perspective, I’d be satisfied if one of their solutions resulted in a self-charging battery that can handle high drainage loads for, say, 20 years continuously before stopping. That’s reasonable perpetual.