The real question is; is that 5.1% remaining after dash reported 0% including the anti-bricking buffer or not? I wonder because I know some have reported driving below zero until that 5.1 % value goes to zero. I can't believe Telsa would allow that, since my understanding is that pretty much means death to the battery. Maybe there is some hidden % reserve not shown by the CANbus data.
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
I think my car is lying to me...
- Thread starter supratachophobia
- Start date
I think 5.1% on your battery is exactly 4kwh correct? So yes, brick protection seems included?
You would guess that, but like I said, some have driven down to 0% from there, which wouldn't make sense if it includes the brick protection.
Let's take a step back. Can the car drive 272 miles at the consumption Tesla defines (in it's own algorithm or the one used with the EPA) with the battery capacity available to it?
The answer is no.
Any other questions after that are trying to explain the 'why'.
You are correct, which proves that not all miles are created equal.
According to the car, BMS, Tesla, etc., 1 mile at X percent at Z consumption DOES NOT equal 1 mile at Y percent at Z consumption.
Good question and I don't know the answer. The percentage that the car reports on the CAN bus is what the app is showing. Since Tesla doesn't document the CAN bus to the public no one knows for sure what this number really means. We do know what it shows to the driver is not true.
Sometimes the car let's you drive beyond zero. I believe it depends on 'how well the battery is doing' at this point. Battery temperature makes a big difference. How you have been driving makes a difference. The power limiter sometimes shows up when I'm at 15% SoC, sometimes only when I'm at 7%. There seems to be other factors/conditions that determine how much you can drive before the car will actually shut down, not just SoC.
A little more of an update. I'm working on a second graph to see if another complete data-set corroborates the 1st. But in the meantime, just wrapped up a long let of a trip with 11% remaining then put it on a charger. But it's dinnertime, so we had to go out with 15% charge, but round-trip said 5% remaining (5 there, 5 back), so we good right?. Nope. Head out, arrive with 9%. Eat, come back, car says 8%, put the car in drive, BOOM, 3% remaining. Cue the ride home at 18-22mph! Arrive with 0.00%, BMS says 0kwh usable remaining.
So yeah, I'm pretty angry right now.
So yeah, I'm pretty angry right now.
Ok that is definitely messed up. I have done that many times. Just the other day I was driving down at a low SoC. My car is pretty consistent and doesn’t drop range suddenly. That’s really important and if your car does that on a normal basis Tesla should investigate.
Yep, you are or much confirming on the charge side what I confirmed on the discharge side. I was hoping this was a battery size specific issue, but if your 85 is doing it then all the battery sizes probably are too. I think this is super shady.
UberEV1
Member
Might the discrepancy be analogous to remaining gasoline in the fuel tank that is still measurable but below the outlet tube (i.e. not pumpable to engine)? Curious if ICE cars calculate remaining range based on what the fuel gauge measures or what is actually accessible from the tank. If the latter, then Tesla is relying on a different standard.
I think gas gauges work similar. When they show zero there is still a little left. The difference is that Tesla does show zero kind of in the same way (before the battery is actually dead) but the range is shows you is based on the total capacity which is not available in any scenario to a driver. So in a way they are lying.
I'm a bit late to this thread... but the usable capacity of a 90 pack is not 81 kW, it's closer to 78 kW (78.5 if memory serves)... I've gone through 4 90 packs and they all test out to 78 kW usable, even when brand new. This number checks out with consumption and charge verification from nearly 10 megawatts of charging and consumption.
Please share how/why you've gone through 4 batteries? And yes, it would not surprise me that brand new there is only 78 usable.
Initially I had a failed cell in one of my packs. I cycle the charge in all my new packs, so the replacement pack ended up being a dud, which they replaced with another new pack... which was the wrong model for my car, so I ended up with a 4th, brand new pack. All of this took about a year from start to finish and gave me quite a bit of time to investigate each pack. So I've tested V1, V2, and V3 packs and they all have about 78 kWh usable energy. My 3 85 packs that I've played with all have had about 75 kWh usable energy, for comparison.
Just to be clear, when you say usable energy, you mean if you drove continuously from a 100% charge, the dash odometer would display 78 and 75 kWh consumed at the point the battery display says 0% remaining?
Hmm, no idea there... the battery display for consumed energy is wildly inaccurate in this context. The easiest way to find out without special tools is to:
1. Drain your car to shut off
2. Turn it back on manually
3. Drain it to shut off again (this is not... great for the battery, YOLO!)
4. Charge to 100%, preferably via CHADeMo or a Supercharger to minimize wasted energy from charging
What your car says went in and what the station says went in should be pretty close to each other - if so, that's your total usable energy. You'll have the added bonus of having a very calibrated BMS, where 0 means 0. This will ferret out any weak cells you have... I have no idea what the long term consequences of this might be, so I wouldn't do it more than very rarely. Once a year at most.
Nope, it's just a waiting game with Tesla. It can take months or even years to get your replacement pack. Just enjoy using the loaner pack for free miles! You can even sell the car while you have a loaner - your original pack will follow the car to the new owner. Happened to me on my P85 - it was over a year waiting for a replacement and I ended up selling the car. They finally replaced it about 6 months after the new owner took delivery... although, I think the loaner pack ended up dying if I recall.