"Batteriser can continue to deliver a 1.5 volt charge in batteries that have discharged down to 0.6 volts. There are more than eight 0.1 volt steps between 0.6 and 1.5 volts, so, in grossly simplified terms, the Batteriser can extend operational battery life somewhere around a factor of eight."
They explained right after that how you get more amp-hours at each voltage step. The math works for that, though I don't think it fits the actual behavior of the discharge curve past 1.1 volts...
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No. That's not how maths works.