Range to zero

[MidnightM00N]

I had a few Teslas and they all continued to drive past 0. A few miles after zero they start to be power limited though and have trouble keeping up with highway speeds. One time, in our Model 3, it would only go about 30mph at the very end before we made it home.

The real scary part with doing this is that if your BMS (battery management system) is out of calibration, it could be wrong and you have less than it shows. This could be why your sister's Model X died at 5 miles -- that's certainly not typical.

Have an old Model S and this is definitely the case. There’s a buffer built in, but it’s hidden from the user specifically to protect against running out early in case the BMS is slightly optimistic. Most times you can drive to 0 or beyond (I’ve gone past 0 by 11 miles before), and the buffer helps hitting 0 more often than not (I.e. it’s usually a bit pessimistic/conservative).

But it also can be optimistic/wrong as I’ve lost power at 7 mi (3%) remaining before too. Capacity (amp hours) is calculated, not directly measured, by the BMS based on a bunch of variables. Things like (according to Tesla support) very cold weather or a series of DC charges on a long road trip in succession without time to sit and recalibrate can throw the BMS and therefore the mileage gauge, which is a fixed estimation based on the capacity calculation, off.

Probably similar for Rivian since they use a fixed ratio to display miles in the instrument cluster instead of a variable guess-o-meter like the older Leafs, i3s, etc used, which was a range estimate based on recent driving habits.

Tesla generally uses a 4kwh buffer. Rivian’s is unknown to this point I think.

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[Eeyore]

Motor Trend did a test with a R1T to see what happens when you don't stop at ZERO. It didn't sound like much fun. As you might guess, you eventually end up with a brick.

The best I've been able to do was 12 miles of range left when I pulled into the carpark at work where the chargers are.

 

[Robin]

My wife took my truck instead of her mache for a work trip so that she wouldn’t have to stop to charge. On the way home she didn’t leave at 100% so when she was 45 miles away she called me and said that it says there is 48 miles of range left. I said, eh, you should be fine. She limped into the garage at 0 miles and 0%. Gotta love it!

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[Supratachophobia]

Have an old Model S and this is definitely the case. There’s a buffer built in, but it’s hidden from the user specifically to protect against running out early in case the BMS is slightly optimistic. Most times you can drive to 0 or beyond (I’ve gone past 0 by 11 miles before), and the buffer helps hitting 0 more often than not (I.e. it’s usually a bit pessimistic/conservative).

But it also can be optimistic/wrong as I’ve lost power at 7 mi (3%) remaining before too. Capacity (amp hours) is calculated, not directly measured, by the BMS based on a bunch of variables. Things like (according to Tesla support) very cold weather or a series of DC charges on a long road trip in succession without time to sit and recalibrate can throw the BMS and therefore the mileage gauge, which is a fixed estimation based on the capacity calculation, off.

Probably similar for Rivian since they use a fixed ratio to display miles in the instrument cluster instead of a variable guess-o-meter like the older Leafs, i3s, etc used, which was a range estimate based on recent driving habits.

Tesla generally uses a 4kwh buffer. Rivian’s is unknown to this point I think.

You are mostly right. But don't forget that Tesla includes the 4kwh in it's 100% range number. It readjusts as you deplete the battery, until 0% on the dash is the 4kwh buffer remaining. Yet another way they lie about the range numbers.

 

[windblowlc]

My wife had a similar episode recently. I had to give her the explicit instructions to go ~60 and to drop it into conserve mode. She was surprised to learn that speed affects range

Of course, the next week her R1S leaked fluid and had to have the rear drive unit replaced (which apparently may be tied to using Conserve mode) so that ended up being my fault.

Of course, blame it on conserve mode!

 

[Wojo]

This past Saturday I made a 200 mile round trip to deliver a piece of farm equipment with my R1T and 2500 lb (empty weight) trailer. I stopped 3 times to charge, 10-15 minutes each time. The third time I stopped to charge, I brought the range up to about 73 miles. I reset the trip meter before leaving the Rhode Island park and ride ChargePoint facility for my last leg home. About 3 miles from home the range went to 0. After pulling in my driveway and dropping the trailer, I connected to my level 2 charger. It took probably 20 minutes of charging before anything positive registered on the range display. When I checked the trip meter it showed 50 miles. It is consistently so disappointing to have the range not only be so poor when towing, but to also be so inaccurate to boot. Another point of dissatisfaction, out of the 3 charger locations I used, the RAN location in East Greenwich, R.I. Was the most expensive @ $.60/kwh. The cheapest was the ChargePoint at the Hopkinton, R.I., I95 exit 1 park and ride @ $.36/kwh. Almost half what Rivian was charging. If dipshit trump doesn’t kill the ev industry, future charging rates certainly will.

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