While I'm oon the topic of ruining batteries because I'm not monitoring their relative voltages closely enough...
Last fall, a fellow EV owner in the UK sent me a portion of his hand-made LED battery monitor that he'd designed & assembled for his Metro EV. (
Rover Metro - not at all the same car
)
Here's what it looks like.
(Note: the height of each LED column is about 3 cm.)
His EV obviously used more batteries than the ForkenSwift - so I only have eight segments from this setup.
It works simply enough: each of the 10 separate LED's in a column represents about 6% from "full" to "empty" for each battery.
Of course, I haven't installed it yet. Winter. You know how it is.
He replaced his home-made setup with a relatively new commercial battery monitor called the Pak-Trakr.
Unfortunately, disaster struck his car: it caught fire and was ruined on New Year's day.