Even if you think what you would say is obvious, please add. This is genuinely something I think makes sense regarding local bus routes given the longevity of light rail and how infrequently routes change, but I also suffer from confirmation bias, so I’m hoping for reasons this would be a terrible idea but obviously would prefer reasons it would be an even more amazing idea than I thought.
Electric busses are actually a lot more complex logistically than electric trains. With a train, you just need a bunch of big-ass transformers and overhead wires. Expensive to install, but very reliable and relatively low maintenance over many years.
Batteries on the other hand are heavy, relatively fragile, degrade quickly, and very expensive. With a 100KWh EV, about 1/3 of the total cost is the battery, so it would likewise increase the cost of a bus.
Charging is another problem, instead of the whole system using energy real-time, you now need a distribution system that can take hundreds of busses at night and charge them all back up, requiring a massive amount of power in a somewhat short time. While it’s nice that energy is generally cheaper at night, you still need the infrastructure that can take that load.
So, it’s not to say that there’s no place for them, just that our main focus needs to be on rail in most places. There are lots of low-density places with cheap power and temperate weather that absolutely need BEV busses, but a lot more with challenging weather, older grids, and medium density that are a better fit for rail.
IMO electric busses needs to have a trolley bus infrastructure on some route so the bus is recharged during the day. Won’t cover 100% of the energy needs, but will spread out the charging time.
I feel like I remember reading about tests on a roadway that could charge your car as you drive on it, like a qi charger. If that gets hammered out, dedicated bus lanes with the charging tech would limit the cost to implement to one lane while busses still have the freedom to reroute if needed.
There’s some infrastructure like that for trucks in germany. Currently in pilot stage: https://www.theverge.com/2019/5/9/18538030/germany-ehighway-siemens-vw-group-electrified-cables-wires-overhead-electric-hybrid-trucks
Trolley buses do exist…
https://en.m.wikipedia.org/wiki/Trolley_buses_in_Vancouver
You can charge electric buses at termini though. Albeit this doesn’t change the challenges much. The electric buses are best suited for lines where the higher capacity isn’t needed and where the line is not likely to be longer than a little over 15 km.