I assume that we're talking about a full-sized school bus, which is a medium-duty truck chassis with a 30 to 40 foot long body on it.
Fitted out as a motorhome, this is likely a ten-ton vehicle. So, with that mass and the huge frontal area, it seems reasonable to me to assume that it will take about five times as much energy to move this vehicle as it would take to move a compact car the same distance.
So... 120 mile range will require five times the battery capacity of a typical battery-electric car with that range. The Nissan Leaf has somewhat less range than 120 miles with its 30 kW-h battery... so, perhaps 180 kW-h, or about double what a Tesla Model S has. You could use six complete Leaf batteries.
A small school bus is on a commercial van chassis, and could be substantially smaller, with correspondingly lower energy needs.
Fitted out as a motorhome, this is likely a ten-ton vehicle. So, with that mass and the huge frontal area, it seems reasonable to me to assume that it will take about five times as much energy to move this vehicle as it would take to move a compact car the same distance.
So... 120 mile range will require five times the battery capacity of a typical battery-electric car with that range. The Nissan Leaf has somewhat less range than 120 miles with its 30 kW-h battery... so, perhaps 180 kW-h, or about double what a Tesla Model S has. You could use six complete Leaf batteries.
A small school bus is on a commercial van chassis, and could be substantially smaller, with correspondingly lower energy needs.