Why do you recommend a 4.0AH battery for one of the batteries in the snow blower? AH means length of run time. Not power output. I have two 2.5AH batteries and not a big area to snowblow. Wouldn't that be fine? The output power should be the same with a 2.0AH battery vs a 7.5AH battery. The blower just shouldn't run as long. Right?