Reportedly one unit has been running for several years. They are supposed to run around 6 months between nickel recharges. The public demos have been sufficient to rule out chemical reactions, though if Rossi was using different techniques to hide wires, or store some kind of battery in some of the shorter demos, it’s possible this is some kind of fraud. But we’ve been tracking it on FR (in scores of threads) since January and no one has figured it out yet if it is bogus.
Even Rossi's scientist friend, Levi, said he would like to see it run for more than 24 hours before ruling out a chemical reaction.