Interesting range observation - Jaguar I-Pace EV400 Forum
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post #1 of 14 (permalink) Old 02-09-2020, 03:23 AM Thread Starter
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Interesting range observation

I find that the range drops steadily coming off a full change but once we get down to 70 miles the rate of decreasing range tends to slow down. I try to plan my charging and not be a perpetual top-off kind of owner.

I had forgotten to charge the night before and I had a drive the nest day to a property about 35 miles away, which means a round trip of about 70 miles. My range indicator said I had 82 miles and I've heard our range is actually very conservative and we can go 10-20 miles more even when the range shows zero. I decided this would be a good mental exercise to reduce rangexiety so with a mere 12 miles (82 - 70) I went on my way.

When I arrive at my destination, I had a range remaining of some 46 miles (there were some hills to get to the location) and so I figured I could easily make it back. What can I say, I guess I like to live dangerously, eh? So I started my drive back, popped it into Eco and deliberately opted for no heat, no fan and even kept the volume lower on the radio LOL. I kept speed reasonable, accelerated gradually and drove conservatively.

Everything was going fine. The GPS navigation originally told me I'd arrive with 1% but it updated to 2% and then 3% (guess I caught a nice tailwind, lol). What I noticed is when I hit about 25 miles the range started getting sticky; I would travel about 2 miles to drop only 1 miles. Then the odd thing happened: at about 8 miles away from my home (and about 22 miles left on the range) I hit really bad traffic. So get this: rolling at a speed of 5-10 miles per hour found me going 4 miles with no drop in range! I've experienced this before when I had a higher range but also in traffic....these cars seemingly nibble the micro-volts when you're barely moving! Even going up a fairly steep hill the 5-10 mph takes a minimal toll out of the range!

I completed the last 8 miles and made it home with about 14 miles on the range. It would have been higher but once I realized I had plenty of range, I started to get jiggy with a Corvette and rather raced the rest of the way home. But yeah, if you ever get hit with close-call on range, definitely drop the speed way down and suddenly you're moving with almost no change in range!
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post #2 of 14 (permalink) Old 02-09-2020, 10:35 AM
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Well some of this probably has to do with non linearity of LiIon cells. Most battery management systems "learn" the behaviour of the cells and try to calibrate a somewhat linear SOC number. So until this happens you may not see a linear representation of the energy available versus SOC, and you may sudden less or "extra" range.
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post #3 of 14 (permalink) Old 02-09-2020, 11:00 AM
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Can you take a screen shot of that trip so we can see the total consumption and stats?
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post #4 of 14 (permalink) Old 02-09-2020, 06:15 PM
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Just a warning... my recent observation was just the opposite and I almost got myself caught out. I won't play around cutting GoM estimates close again.

In summary, with 21 miles remaining I switched to low power mode. The car dropped 16 miles off the GoM in the next 10 miles and switched to a even lower power mode where it would only barely accelerate with 7 miles reported remaining. Fortunately I was able to limp home the remaining 2 miles to home, arriving with 5 miles and 2% remaining.

See my post #26 in the SoC thread here: https://www.i-paceforum.com/forum/55395-post16.html

There's a screenshot of that trip.
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Last edited by StormRune; 02-09-2020 at 06:20 PM.
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post #5 of 14 (permalink) Old 02-09-2020, 06:30 PM
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I'd be careful when going low. I lost "situational awareness" once and focused on the range rather than state of charge. At 50km of range (and 30km left), mine dropped to 30 in one second. Went the last 30km in low power mode (and fingers crossed), seemed to gain and I entered the charger parking lot with 12km left, and it went to 0 instantly. Luckily the charger was on that side of the parking lot. Came close to having to push it for the last 50 feet!
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post #6 of 14 (permalink) Old 02-11-2020, 12:28 AM Thread Starter
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Originally Posted by rcomeau View Post
I'd be careful when going low. I lost "situational awareness" once and focused on the range rather than state of charge. At 50km of range (and 30km left), mine dropped to 30 in one second. Went the last 30km in low power mode (and fingers crossed), seemed to gain and I entered the charger parking lot with 12km left, and it went to 0 instantly. Luckily the charger was on that side of the parking lot. Came close to having to push it for the last 50 feet!
Hmm.....I've read that even when it reads 0 miles left, we still have another 5-15 miles to go before we stop moving. Obviously not an ideal thing to do but still, they say it's quite conservative.
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post #7 of 14 (permalink) Old 02-11-2020, 12:29 AM Thread Starter
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Not sure where or how to access that info. This was perhaps 3-5 days ago, would it still be available? I'd be happy to snap a pic, please guide me to this info!
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post #8 of 14 (permalink) Old 02-11-2020, 12:48 AM
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Quote:
Originally Posted by Steve R View Post
Not sure where or how to access that info. This was perhaps 3-5 days ago, would it still be available? I'd be happy to snap a pic, please guide me to this info!
There was a range test done with a few EVs.
I-Pace went 20 miles after 0% SOC before it just stopped

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post #9 of 14 (permalink) Old 02-11-2020, 08:42 AM
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Quote:
Originally Posted by PS702 View Post
There was a range test done with a few EVs.
I-Pace went 20 miles after 0% SOC before it just stopped
I think that was just dumb luck. I think the "math", if they want to call it that (I think it is squirrels throwing darts on the wall with GOM values on the board), has a habit if leaving a remainder, so rather than smoothly going to 0 (linear equation with no constant), there is a number. If that number is positive, you get a few km after hitting 0. If the remainder is -ve, you lose distance at the last minute. Mine went from 12km to 0 with no additional warning or super low power mode. Just 12km to Beep! Stop care safely, system shutting down.
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post #10 of 14 (permalink) Old 02-12-2020, 08:53 PM
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Thanks for posting your story. The specificity and details are helpful. Being new to e-ownership I have range anxiety. So hearing such things help. What happens is we run out on the road? Are the likes of AAA equip to handle a charge? Or are we forced into towing? Yow.
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