Great work again, Joe!
Too bad the reporter doesn’t understand how batteries are charged. Twelve-volt lead-acid batteries are charged by chargers putting out 13-14 volts or so. You can’t charge a battery with 12 volts. Therefore, right after the inmates start pedaling, they are putting out more than 12 volts. A battery charged to 12 volts is only about 20% or less charged. When the batteries are fully charged, their output is about 12.6 volts to as high as 13 or more.
But I don’t expect reporters to understand anything having to do with science.
You are assuming that there are batteries. I am not sure this is the case.