Waterloo Region built an urban light rail [1] system ten years ago and overall I'm a huge fan of it, but the snarl of wires required at each intersection to make the overhead lines turn a corner is unfortunate. It would be neat if you could have the power only on straight runs and have frequent brief interruptions.
It says in the article - only 20-30% of the route needs to be electrified for these to work. And the batteries can be recharged at stations in 20 minutes.
"It shows that Siemens Mobility’s battery bi-mode trains would only require 20 – 30% of a line to be electrified. These trains, utilising Lithium Titanate Oxide battery chemistry, can charge their batteries to full capacity in 20 minutes whilst moving along the electrified sections or charging whilst stopped at stations."
As for charging, Jago Hazzard has a video on a fast-charge trial[1] for a battery-only route. As it's using a modified tube train, I'd assume it's lighter and thus requires smaller batteries, but recharging from third-rail takes roughly 4 minutes.