Dave doesn't have access to it. There is only one of these
OCube things in the wild.
Honi soit qui mal y pense.
Anyway, let's assume this is not a complete scam but uses energy harvesting to provide at least
some function.
Since there are no solar cells visible, they could use harvesting from WiFi or other electromagnetic waves.
I guess harvesting to supply 1mW devices is somewhat realistic, so letting aside obvious losses, they could maybe harvest 1 mWs within a second without groundbreaking technology.
-> 1h -> 3.6 Ws
-> 1d -> 86.4 Ws
-> 1w -> 604.8 Ws
A modern smartphone's battery has around 2000mAh at 3.7V -> 7.4Wh -> 26640 Ws
So after only about 44 weeks, there would be enough energy harvested to charge a smartphone (well, no losses and so on).
Now let's be absolutely optimistic and assume they could somehow harvest 10mW, it would still take more than 4 weeks to harvest enough energy to charge a smartphone.
Taking into account the losses for trickle charging and the self-discharge of the battery/capacitor, the numbers will look even worse of course. Actually, probably
much worse.
So even assuming this is not a complete scam and they put some kind of state of the art energy harvesting technology inside, it's hard to believe they aren't aware that the amount of energy harvested is too small to be of any real word use that they claim.