[slaw]

Watt/hour is speed of power. It doesn't make any sense.

[Tostino]

No, you misunderstand what it means in that case. Watt-hours are comparable to joules. 1 watt-hour = 3600 joules.

[slaw]

watt*hour=joule

watt-hour: you cannot subtract time from power, it doesn't make any sense.

watt/hour: delta of power per time, something very weird.