eNate
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Re: Thoughts on cutting off 100% to account for lost capacity?

Wed May 20, 2020 8:02 am

ksnax wrote:
Sun May 17, 2020 11:15 pm
...the i3 adjusts usable displayed capacity based on a formula and recent performance history. There really isn't any way to measure a battery directly for capacity. Voltage values are interpolated into range, but even a mostly cooked battery can still display full voltage or any value in between, so it is always just an estimate.
jadnashuanh wrote:
Mon May 18, 2020 2:26 pm
The i3 just will not let you use the entire battery capacity...


That furthers my point. The car is already displaying "false" capacity. 100% displayed = 96%, and 0% displayed = 10%. That's manipulation for the benefit of the driver.

So my suggestion is an additional manipulation.

Showroom new, my car goes 100 miles on a charge, so my SOC reads 100%.

Over time, through voltage measurements and logged data over thousands of miles of driving, using fancy algorithms and lookup tables, the car sees my battery has degraded 10% and maybe my average range has decreased to 90 miles.

In that instance, fully charged, my SOC would read 90%. It would never display any higher. It would be a very "in your face" acknowledgement that the battery had degraded capacity. If I sold the car, the buyer would have a very good indication of what they're getting into.

Make no mistake, this wouldn't be a "floating" percentage that would increase on warm days and decrease in cold days -- this would be a carefully tracked and "permanent" indication, that could perhaps be adjusted with a dealership capacity test, supposing that could provide more accuracy.
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skeptic
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Re: Thoughts on cutting off 100% to account for lost capacity?

Wed May 20, 2020 8:27 am

I think it would cause far more confusion. Non-stop "why will my car not charge all the way" comments. As ICE cars get old they sometimes lose mpg, or when you put different tires. Doesn't take much to get used to the new max range per fill-up when you throw a set of big mud terrain tires on your truck, I don't think it will be hard to adjust to a lower range per charge as the battery slowly loses capacity.

eNate
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Re: Thoughts on cutting off 100% to account for lost capacity?

Wed May 20, 2020 9:36 am

We can rest on "we've always done it this way" but as I see it, the battery represents the largest and perhaps most expensive component in an EV, and its health should be front and center to the owner.

BTW I'm not talking i3 specific. I'm suggesting across the board industry practice.

We're all seen the posts where an owner "guesses" their battery has diminished, goes to the dealer to explore a warranty assessment, and gets the car back reprogrammed and magically cured -- suspecting the invisible reserve has been tapped into.

I don't think we have to live behind the rose-colored blinders that is a false 100% indication. EV owners can be treated as rational humans capable of understanding that all batteries degrade with age and use, and be presented with its condition as the car is capable of calculating, without having to dig through buried diagnostic tools.
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jadnashuanh
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Re: Thoughts on cutting off 100% to account for lost capacity?

Wed May 20, 2020 12:55 pm

It's not designed to be a range to empty indication which IS displayed...it's designed to indicate whether the battery is charged as much as possible, whatever that is.

I think most people would be upset if it never 'charged' to 100%, and would wonder why when they plug it in, it isn't charging to achieve that value.

If you know your car well, and have tracked it over many miles, you'd have a pretty good idea of capacity based on the miles to empty indicated. Throw in variations in temperature that will sometimes significantly affect your range, and changing the percentage readout could make things even worse. I'm open for change, but I don't think this one is the proper one. Now, they could make it an ADDITIONAL displayed option, but with the known variability in that calculation, I'm not sure that it would really clarify things for the average user.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV
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MKH
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Re: Thoughts on cutting off 100% to account for lost capacity?

Wed May 20, 2020 1:13 pm

I don't think we have to live behind the rose-colored blinders that is a false 100% indication.
Except for it's not a false 100% indication. It is 100% of the battery available to you.
Mark H.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 19 inch 427 wheels, EVoInnovate EVSE

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