I went past a juice point actually in use on the way in today, just north of Waterloo Bridge and opposite the Lyceum Theatre. There are 12 of them in Westminster, and you can recharge your electric vehicle here free for up to three hours.
The points - which look disconcertingly like they should be dispensing smoothies - carry the warning 'Contains electricity', presumably for the benefit of those with an allergy.
Cyclists have a similar but more comprehensive network of juice points of course. They're not free, but some of them are very reasonable, such as the ones run by Wetherspoon's.