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lost critical range while parked for 20 minutes

lost critical range while parked for 20 minutes

I was driving my model S100D and stopped for 20 minutes with 26 miles range left and 17 miles from home. When I got back into the car after only 20 minutes, the range was 15 miles, an 11 mile loss with no heat, radio or anything else drawing power. Can anyone explain this? Unexpected range loss at a critical time, so I had to charge briefly to make it home. Would I have made it home had I not I not stopped?
Thanks for help with this!

murphyS90D | 29 octobre 2019

There were plenty of microprocessors drawing power. If the 12 volt battery dropped to the recharge SOC the HVB was used to recharge it. What was the temperature? Cold air can reduce the HVB SOC but normally there is a message on the screen telling you the car may not restart.

Anthony J. Parisio | 29 octobre 2019

How did you get home?

tes-s | 29 octobre 2019

That has not happened to me. But I also can't remember stopping with less than 10% range left and not being at a charger. The only time I go below 10% is when on a trip and heading to a charger - other than that I generally keep it above 20%.

jfemd.va.us | 29 octobre 2019

Why risk running out of charge in the first place? I can only remember one or two times when I got down to 25 miles of range or less (and that was four years ago when superchargers were not as prevalent).

dougk71 | 29 octobre 2019

We are entitled to explanations of this huge waste of power from Tesla. 11 miles is over 3Kwh and in 20 minutes that is a 10 Kw draw. This is close to the draw of running the A/c in an average house.
Sure if it didn't happen to you then you can brush this under the rug but if one car does this then any car has the potential of doing this. Now I suspect the information provided is derived algorithmically in that Tesla just has the battery voltage to measure charge and the retrospective use of the battery capacity from the actual driving record. This computes to a miles available number. Range anxiety is a human condition and Tesla needs to disclose how the computation of range is made...if these range numbers are accurate then the Tesla is not a wise manager of resources when parked.

pa30pete | 29 octobre 2019

The same thing just happened to me recently. (2017 P100D). Arrived at doctor appointment with 45 miles range left. I was getting alerts on screen that colder temps can reduce range. Also received alert that Sentry mode unavailable due to SOC. When departing doctor's office one hour later, was surprised to see range had dropped 36 miles. Had intended to make supercharger my next stop anyway so I got there with 31 miles range left
In fairness to Tesla, the temps in north Illinois have been cold. As a rule, I try not to let my charge level get below 20% as I understand it is not good for the battery pack.

p.c.mcavoy | 29 octobre 2019

I’ve experienced what looks like significant drops in range after I’ve driven the car for a significant distance and then parked it with battery at relatively low SOC, say around 10%. I’ve captured it in log files using VisibleTesla and actually see that it’s a drop in apparent range that occurs suddenly, say between two data points maybe 3-5 minutes apart. I’ve interpreted that as not really due to energy being “consumed”, but likely due to the battery temperature dropping. Physics of energy storage in a battery is that there is less energy that can be extracted from the battery when cold than hot.

The ambient temperature conditions in these situations has not been what you’d consider as “cold”. Instead it is the battery temp is actually elevated above ambient from extended operation and as it cools down to ambient, at some point, likely goes over a temperature break-point in the BMS range calculation algorithm such that displayed range is reduced.

That’s been my interpretation of what’s happening when I’ve observed this. Could you likely have made it if you had not stopped? Possibly. That’s where I’d say always realize that when you park your car at a low SOC you may find that you’ll likely see what looks like more vampire range loss than you might expect.

dougk71 | 29 octobre 2019

A 10Kw draw is a significant draw and needs a significant explanation. Tesla has open patents but often is opaque when it comes to informing owners of the parameters that are used in providing information to owners. Tesla has engineers let them transfer unfiltered details to owners.... we are deserving of this. Some owners may not care but that shouldn't result in others being denied the details of how their car develops the information we see presented.
What is going on to consume the energy when your car is parked?
We expect energy to be consumed when in motion but when parked a reasonable expectation is that the Tesla. would be frugal.
Maybe the calculation of range is deeply flawed after a car is parked for sometime ..if so why can't Tesla disclose it?

barrykmd | 29 octobre 2019

pa30pete | October 29, 2019
The same thing just happened to me recently. (2017 P100D). Arrived at doctor appointment with 45 miles range left.

Why are people not charging their cars at home? Or did you have 200+ miles of errands/work prior to your doctor appointment?

TeslaTap.com | 29 octobre 2019

@p.c.mcavoy - Sounds like the most likely reason. The battery can cool fairly quickly. When you get back in the car after sitting for a while, it needs to turn on the battery heater (6 kW) to get the battery back up to temp, so it may be doing a calculation on how long the heater will need to be on before the battery has more power, yet it's using quite a bit of power while near depletion and the battery has lower than normal energy due to temps.

fishbro | 29 octobre 2019

The 11 mile range loss was in 70 degree temp outside. I was coming back from a trip with no chargers nearby in a wilderness area. A lot of the drive home was downhill and I gained some miles before stopping briefly, where the range loss occurred. This was very disturbing as I rely on the range readout when trip planning, as we all do. Some information from Tesla about this would be nice.

TeslaTap.com | 29 octobre 2019

Sounds like temps are not the issue. Generally, I avoid under 10% SOC, so I don't have any expertise at running it to 0% SOC. Since you were running downhill, the watts/mile would be quite low. If you continue at that rate, you would have longer range. I've always heard the range calculation is static at a fixed watt/mile rate, but perhaps they tweak it a bit. I'm guessing here, but when you stop and get back into the car, it has no idea where you are going and resets the range based on the EPA watt/mile rating, which would be quite a bit higher than that you got while going downhill and the displayed range would reflect this.

I don't think Tesla has ever disclosed exactly how the range is calculated.

Bighorn | 29 octobre 2019

It was probably a recalculation based on the recent poor efficiency of having draws and not moving. You didn’t lose that much charge in reality and probably would have had a more accurate range estimate after driving a bit and would have gotten home with miles to spare. You should have had a screen message when you shut down that said you’d have considerably less range if the battery cooled. Who wants to take that risk of the flat bed of shame? Silly, in most circumstances, to be driving so close to empty in the first place with 100 kWh under the hood, but I’ve only skimmed so don’t know your particulars.

dougk71 | 29 octobre 2019

Well, absent a disclosure from Tesla it will take some one with a flat bed to follow the Tesla that just lost 11 miles of range after parking 20 mins and see how accurate the range actually was. Unfortunately the guinea big Tesla battery will be put at risk during this hypothetical test. Tesla step up please...range anxiety isn't reduced by owners not knowing how the range is calculated. In fact some could question how accurate is any range.
How far can you really drive a 100Kwh Model S...must it be non stop?
I believe Tesla is realistic about this max range but what if you park for 20 mins once or twice when measuring the maximum driving range.?

inconel | 29 octobre 2019

The sudden range drop only seems to happen at very low SOC. Tesla even has a warning display for that case. And p.c.mcavoy and TeslaTap explanations make sense to me.

inconel | 29 octobre 2019

The discharge voltage of Li-ion battery drops significantly at colder temperatures which is what happens when the car is parked after an extended drive and the battery starts cooling down to ambient temperature. While it would be nice for Tesla to explain to us that physics phenomenon I am fine if they don't :-)

At colder temperature the battery internal resistance is higher which will warm the battery up faster when we start driving again. With a higher SOC I guess the battery will have time to warm sufficiently up so that the lower initial discharge rate has less impact whereas a low SOC battery does not have enough range left for that.

cfishkin01 | 29 octobre 2019

Happened to me. 6/17 75D, 60 degrees. Long road trip, about 3 hours in the car, Cape May , NJ to Nyack, NY. Pulled into the driveway with 25 miles left. Unloaded the luggage, came back out an hour later to put the car in the garage. Showed 11 miles. Shook me up a bit. I thought I was rock solid to make it home. Not so sure now. Will try not to do that again.

Bighorn | 29 octobre 2019

@cfishkin
You were pretty solid. The 25 would have held without the stop if you'd kept driving. The battery cooling after arriving is also going to use some energy.

dougk71 | 30 octobre 2019

Often there are many reasonable explanations for a specific issue. Several of the explanations could be the correct ones. I thank those that take the time to try to explain these issues but though unlikely it may be they could be wrong.
This small uncertainty is at the feet of Tesla...why not publish the range calculating algorithm?
Many expect it is approximate and is less so after the Tesla is parked for awhile.
I saw based on the range some large draws when parked overnight in a home garage.
An earlier version of the range calculation had the car lose 3 miles overnight an newer calculation had it at 11 miles.
With no explanation from Tesla time was taken to explore the several possible reasons. Similar cars in similar situations had differing range losses. It in the end it just remained a puzzle.
Later software releases reduced the estimated loss.
I just accepted that range estimation is good when the car is moving and much less so when the car is parked.

pa30pete | 30 octobre 2019

@barrykmd
I had just returned from a trip to central Wisconsin and planned on charging at the local 72 KW SC after
Doc Apt. With free SC charging for life, I plan/use the local SC in Glenview IL (near my home) when I can.
Also, my post should have read "dropped to 36 miles".