Range Warning, Where is it?

[Heima]

I tried to search if others have asked this question, but was denied, with the explanation that Warning Range were too common of words.
Ok.....
So for shits and grins, I took my 2017 down to 0 miles range. Fortunately I was near a stout 240V charger.
I started the drive with 8 miles left to go, and 8 % SOC. I took a country road and was doing an average 50 mph.
If I punched it, the car responded as usual.
No messages of limited range, no icons of turtles, no color changes. Where were the warnings?
At 4 miles left, I turned around and drove back. The SOC was at 6%. The car would accelerate as usual.
At 1 mile left, the range circle in the small navigation screen was shrinking.
Soon, it was smaller than the arrow representing the car.
Still, no words, no warnings, no flashing lights.
Finally, I was at the charger, but decided to drive around the block a couple of times.
Still could accelerate quick, and I must have drove for 2 miles before it went to 0. Then drove back to the charger.
Charging, SOC was 4%
Never was there a message about reducing speed, reduced range, turning off climate (though it wasn't on), charge now, turtles, snails, sloths with X-out eyes, nothing to let me know that I was heading into a world of hurt if I kept driving.

The Fiat 500e will give you a turtle, but you will slow down before that. The range and SOC will go from green to yellow at 20miles or 15% SOC, and then orange, and then red.

So will a FFE tell you that you are soon to be SOL, or is there something up with mine?

An aside, after charging to 100% a couple of times after that event, I checked the Kwh to empty with Forscan. 28.006.

 

[jmueller065]

One would think that seeing you have only 2 miles to go is enough warning??

You are correct: The FFE has no warning that you're about to run out. Considering that the max range of the FFE is about the time the "low fuel light" comes on in a gas car you would expect the low range warning to be on all the time :lol:

About the only thing you'll get is sometimes the car will give you a "Stop Safely Now" error when you're completely out of battery--of course its too late at that point.

 

[triangles]

:lol: Are you saying they removed the battery low warning when you are down to 10 miles left on the guessometer from the '17??? I have to agree with jmueller065 seeing that you only have single digit miles left isn't enough of an indicator for you?

 

[Heima]

Actually there is another side to this story. I was wondering if this lack of a warning, was some indicator of how the FFE processes its battery telemetry. I was thinking, that maybe the warnings did not come up, because the battery state was fine, and that the calculated miles to go was really off.

We know the car has a shunt or hall effect sensor to measure the current flow. The car can also measure the battery voltage. From these two data points and elapsed time, power consumed can be calculated. The car also probably has a lookup table of available power according to battery voltage, and also a constant of the maximum power available. Throw in the velocity of the vehicle, it is possible to calculate in how many miles and in how much time, the battery will be depleted. This is all using linear equations. Note, from the data I have seen for other batteries, the lookup table might be approximated by a 3rd degree polynomial.

The above information is processed through whatever polynomial/series function to determine Guess O Meter range. If you were to drive pedal to the metal for a time, and then backed off to a crawl, your calculated range would be short, even though you have X battery capacity remaining. Conversely, if you drove like a turtle for a time, and then stood on the accelerator, your calculated range would be long, even though you have the same X battery capacity remaining.

So going back to my experience, to go from 1 mile to 0 miles, I had to travel about 3 miles. At 0 miles, there was still 4% SOC. Might this have been a situation where the GOM would have displayed 0 miles continuously until the SOC had actually dropped to 0%? And only at that time, would a SSN or other message appear?