Just looked it up out of curiosity – the advertised WLTP range for my car is 388 miles.I am a bit surprised that the real-life range is that close (but of course not practical as you really don’t want to go below 10% EVER)
aart wrote:
My second one has miraculously increased in capacity. Spec said 450 km of range and I’m recently getting indications of 500 km range.
I have similar experience with my Kia E-Niro. Advertised range is 450 km and I regularly see 470-480. The car is 2 years old and has run 60 000 km.
But it depends very much on how fast you drive. Most of my driving is in cities or on country roads with an 80 km/h speed limit. If you go up to 110 km/h on a motorway then it is a very different story. The same in winter months.
Those are the numbers shown on the display. Whether you would actually get them is a different question – ever noticed how the last few % of your smartphone battery drops like a stone, much faster than it drops from e.g. 80%-70%. Probably no-one takes an EV low enough to test it out.
As Peter suggests, I would bet the house that they manage the stated capacity in software at both the high and low end. When new what it displays as ‘100%’ and caps charging at will be less than 100%, and as time goes on it opens up more real capacity to avoid showing degradation. Likely they allow you to run lower as time goes on too.
Degradation is unavoidable. Making it obvious to the use is avoidable.
Faking these things is absolutely standard. Whenever I was asked to design something (I used to do a lot of custom stuff) with a digital display, the customer laid down a spec for what to fake. It may be trivia like implementing hysteresis so you don’t get a display rapidly changing between 25 and 26 if the temperature changes between 25.499999 and 25.500001, or it can be something deeper. With a battery powered product you fake a lot more.
With an EV you probably have a 5% margin and as that is used up you drop the displayed capacity from 100% to 99% (instead of 95%). That will be good for say 3 years (the typical financing contract duration; almost nobody will offer GFV finance after that, according to my sources at a nearby car dealership). So you have a happy customer for 3 years who sees only a 1% battery drop.
The car business has a long history of going to a lot of complexity for faking emissions 
Graham wrote:
I would bet the house that they manage the stated capacity in software at both the high and low end.
Definitely at the low end – the car will continue to drive for a bit even at 0%; but it is difficult to tell for how long. The main issue here is that it only needs for some cells to be “empty” to make driving impossible, so at some point you would do damage so the battery management system shuts it down.
At the top end, it depends on the manufacturer. You can probably tell by the charge speed – it drops to a trickle for the final % if 100% is the true capacity. The Porsche Taycan is widely reported to have such a buffer at the top, the Teslas don’t seem to have one (except for the models which were sold with larger physical batteries and a software limit on capacity which could be unlocked for a fee).
Graham wrote:
Probably no-one takes an EV low enough to test it out.
I’ve taken my down to 6% and I couldn’t notice any difference in drop rate.
Do they have any sort of power conservation mode when they get very low?
Peter wrote:
The car business has a long history of going to a lot of complexity for faking emissions
A very good point. With the history of that business, would you trust what they tell you about batteries?
Graham wrote:
Do they have any sort of power conservation mode when they get very low?
They do, one of my colleague was not very happy that his EV decided to turn off the heating of the occupants because of that. This happened when outside temperature was -16°C, hence him not being happy!
Graham wrote:
Probably no-one takes an EV low enough to test it out.
I have taken it to zero and below. There’s actually some juice left even at zero indicated, probably 10 km or so, but I have never driven so long that the car would stop all together. But, I have had poor voltage in the 12V battery a couple of times. The first time I had no clue what was going on, the car was dead, nothing worked. Called help, and out of the truck came a dude with a jump starter. I said, look, that’s an electric car, and he just laughed and said, of course it is, and this jump starter will fix it. What happened was the 12V had low voltage for some reason (severe cold for instance). Everything (except the motors) run on the 12V, and when the voltage drops, nothing works, not even charging the 12V.
After that I bought a couple of these tiny Li-Ion jump starters. Had to use it once. According to the car rescue person, this is the usual reason why EV suddenly won’t work: bad 12 V battery 
