If you’ve got a heat pump, you’re probably looking at several kilowatts to keep a big battery warm. 5 is probably generous. I’d imagine a few hundred kilowatt hours in a battery like that (figure roughly 1 mile per kwh). If a bus is on the road for 10 hours, you’d be looking at a loss of 50 kwh, leaving about another 250 kwh (about 250 miles) for driving. A quick search says a school bus usually drives 65-75 miles daily.
Can they be plugged in to help things? Of course. Is it absolutely necessary to? Probably not. Every little bit helps, but if we’re talking about just 120V you’ll probably only get about a kilowatt, which wouldn’t be huge even with a heat pump in cold weather (unless I’m grossly overestimating how much the heat pump would need, which is possible, but would also leave even more battery capacity by that calculation)
For heating, EVs experience pretty severe drain. That includes heating the battery and heating the cabin
Most have heat pumps which are more efficient than electric resistance heating, but it still results in a significant loss of range
For the busses (and car EVs) they just need to factor that in when designing the battery storage and vehicle storage itself
If the bus can sit in a temp-controlled environment or hooked up to even a 120V charger, it can keep warm without sacrificing range
If you’ve got a heat pump, you’re probably looking at several kilowatts to keep a big battery warm. 5 is probably generous. I’d imagine a few hundred kilowatt hours in a battery like that (figure roughly 1 mile per kwh). If a bus is on the road for 10 hours, you’d be looking at a loss of 50 kwh, leaving about another 250 kwh (about 250 miles) for driving. A quick search says a school bus usually drives 65-75 miles daily.
Can they be plugged in to help things? Of course. Is it absolutely necessary to? Probably not. Every little bit helps, but if we’re talking about just 120V you’ll probably only get about a kilowatt, which wouldn’t be huge even with a heat pump in cold weather (unless I’m grossly overestimating how much the heat pump would need, which is possible, but would also leave even more battery capacity by that calculation)