What Car? magazine have a done a feature on how far a selection of EVs will travel (on test track) and what happens when they run out of power. Tesla is still the most efficient but interesting that they’ve said that the 3 and Y both behave differently when they run out of power.
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What Car EV feature
- Thread starter up_north
- Start date
I don't believe or trust reviews like this because they've not caught up with a few material facts
1 - over the air software updates can change how cars behave in ways we don't always see. Does the M3 and MY perform differently or are they on different versions of software?
2 - The M3 is also an old one, maybe only a few months old but with the older smaller battery as the current M3 and MY LR now have the same battery, yet they seem to have taken the range figure for the new M3, bit of a fail and explains why the 18% shortfall.
3 - quite a few comments elsewhere have talked about BMS calibration and cell balancing, and my limited understanding is the issue with the BMS is it can struggle to predict where 0 is over time and becomes slightly pessimistic. In other words, the cars drops the available range shown, but the range is still there. My long forgotten physics A level would lead me to think that once a car hits zero, the worse the BMS calibration is the more the car still has in reserve. Ergo, to suggest the car has an 11 or 13 miles buffer is a function of BMS calibration and not a design decision, and a calibrated BMS will have a smaller buffer.
I may be mistaken in some of the detail but a battery running down isn't as easy to assess as an emptying petrol tank.
1 - over the air software updates can change how cars behave in ways we don't always see. Does the M3 and MY perform differently or are they on different versions of software?
2 - The M3 is also an old one, maybe only a few months old but with the older smaller battery as the current M3 and MY LR now have the same battery, yet they seem to have taken the range figure for the new M3, bit of a fail and explains why the 18% shortfall.
3 - quite a few comments elsewhere have talked about BMS calibration and cell balancing, and my limited understanding is the issue with the BMS is it can struggle to predict where 0 is over time and becomes slightly pessimistic. In other words, the cars drops the available range shown, but the range is still there. My long forgotten physics A level would lead me to think that once a car hits zero, the worse the BMS calibration is the more the car still has in reserve. Ergo, to suggest the car has an 11 or 13 miles buffer is a function of BMS calibration and not a design decision, and a calibrated BMS will have a smaller buffer.
I may be mistaken in some of the detail but a battery running down isn't as easy to assess as an emptying petrol tank.
The danger of these kind of articles is that when you see numbers in print you have a greater tendency to believe they are facts! It’s interesting of course … but that’s all. I won’t be assuming that my car can drive onwards happily for x miles so whichever model I have I will be finding somewhere to plug in before 0%.
Sparkeur
Member
Who actually cares what the reserve is...why would you worry about something you will never have happen? This sort of drivel sells magazines but it is no longer relevant - anymore than doing the same exercise on an ICE car is. Charge at home up to 80% for daily driving and then follow the charging networks for destination driving. I've been doing this for two and a half years and 50,000km across Europe and never come anywhere near having a problem. There needs to be a society of EV manufacturers pushing out PR to get the facts across and not let this nonsense continue to grab headlines.
True! Such an article implies that this is an issue EV drivers have to face as an inevitable aspect of ownership ... so you'd better know about it. (Sucking the rusty contents of the bottom of your fuel tank in an old ICE when on empty might be worth an article ...)
It also serves to reinforce the anxiety that people with electric cars need to think about running out of power. How many of us has this ever happened to?
I disagree that the article is pointless. Of course you would hope that people aren’t stupid enough to get down to zero, just like you would hope people aren’t stupid enough to let their ICE car run out of fuel…but it happens, so it’s worth knowing what to expect if the worst happens and for some cars, that knowledge itself might be enough to deter people from pushing their luck.
This clarifies the Model 3 discrepancy.
This clarifies the Model 3 discrepancy.
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Yes, I don't think it's pointless as it does have some value for prospective EV owners to know that EVs don't just stop at 0%. However, perhaps not so much when you get to the level of comparing models with 13 as against 15 miles as if that makes a real-life difference to how you would use your EV or base a choice of EV.
They should have used the range of that model, the chart shows a crazy shortfall because it’s wrong.
They’re also setting the expectation you have 10 or so miles after zero, I think you’d be living dangerously assuming that in real life.
But it highlights a problem, maybe consequence is a better word, mentioned elsewhere, every few months a Tesla is different to the same model but made earlier, any article saying this is how a M3 or MY is is often only relevant to that production window. The article suggests a M3 and MY behave differently, but do they, or does a 2021 model behave differently to a 2022?
I don't get the Symonds fascination, he gets the battery details wrong more often than What Car. The more I watch the more I cringe at his non conclusions and methods.
I agree he can be cringey. He is very car salesperson-y and not scientific.
However, I’d rather he do this to a car in his possession and I learn something from it, than risk doing it in my to be delivered car.
When has YouTube ever been the go-to destination for thoroughly tested, unbiased and peer reviewed data? Bjorn, EE and Munro are about the closest we have to that, and even they're not perfect in that sense.
I agree, but people seem to punt Symonds videos as if they explain something when they never do, or not accurately.
I haven't watched them all, but driving 300metres in 2 cars, one with and one without the laminated windows and a phone app trying to measure the sound, the newer car with the laminated windows actually recorded a louder sound and his conclusion was they were the same or maybe the new car was better. Announcing the new battery in the LR not long ago that actually came out 6 months ago, driving the i4 around an industrial estate trying to work out the range then concluding it was pointless, you get my drift. You can tell he's great salesman, he talks rubbish and people still believe him!
sleepydoc
Well-Known Member
This doesn't really matter, though. The cars were all run until they died and as others pointed out, you're not going to voluntarily run the car below 0.
Oops! Do you think there was reason for the BMS to be out of adjustment? (Eg. Car not been run to high or low percentages for a long while before the journey in question?)and here i am with an S that ran out of power at 2% and only 1/4 of a mile from the supercharger and i had to get a tow.
airborne spoon
Active Member
Oddly enough my battery is quite well balanced after all these miles. And that time I ran out of juice was a couple months ago and having gone to 1% and 2% multiple times in the past I was expecting the same to be good. I even drove super slow and drafted a truck. But sometimes the car just says **** you and dies for the hell of it I suppose.
It matters because it sets the expectation there is a reliable buffer, and there might not be one, or not as big as subsequent posts have shown.
It is a pretty big article to cover something that you'd never do, I don't recall them ever doing it for petrol cars where they compared how a BMW ran out of fuel compared to a Mercedes. So I also have a concern it's reinforcing the mindset to those who do not yet have an EV that range is an issue and you need to know this kind of thing because it's important.
