In article ,
Christian McArdle wrote:
Because the cells are all standard sizes they have a maximum capacity
in amp hours. Increase the voltage and everything else being equal,
the amps drop so the battery lasts longer.

Except that cheap brands use lower quality cells and lower quality, less
efficient motors, so, IME, a 12V brand name performs like a 18V cheapie.

Indeed. That's why I put 'everything else being equal' ;-)

--
*Honk if you love peace and quiet.

Dave Plowman London SW 12
RIP Acorn