Unpleasant Experience nearly running out of charge on M6

[TheManofMead]

To put this in context, I have owned my Model S for 2 years, and we have recently acquired a M3P for Mrs Mead. Had to go to Scotland last weekend, and as my S had a puncture, I had to take the M3P.

Now I completely accept that what ultimately unfolded was of my own making, but the contrast in range loss on the M3P compared to the Model S was disconcerting to say the least.

I set out from Scotland to travel back to Cheshire. Saturday evening, perfect weather conditions sunny and warm. Not sure about wind and direction and maybe it was strong against, considering what was to unfold.

I wanted to make the 260 mile trip with only 1 stop. I had just collected my elderly mother from hospital and wanted to get her back home with minimum charge stops. At Forth Valley Hospital near Falkirk the M3P said 202 miles range. 144 miles to Tebay charger was my plan. 56 miles to spare, no brainer I thought. What could possibly go wrong.

On approach to Gretna Services (last charge possible before Tebay) the car was giving the red warning not enough charge to reach destination without stopping at Gretna. At this point its 48 miles real world to Tebay and the car showing 63 miles. This was where I made my grave error. Extensive experience with my Model S told me there was no way I would ever not make it based on 48 miles and the car showing 63 miles. 15 'spare' miles for a 48 miler. It was unthinkable this could or would ever be a problem in the Model S. I concluded the M3P was being unduly cautious and it wouldn't be a problem. Bad mistake.

With 24 miles to go, the car showed 31 miles left. Still 7 to spare, ease off the speed, it will be ok.
By 12 miles to go the car showed 12 miles left. Really getting worried.
By 9 miles to go the car was showing 7 miles left. This isn't going to end well.
By 5 miles to go the car was showing 0 miles left.

All I can say is that for those of you familiar with the final miles to Tebay travelling South is that it is steep downhill for those last 2 miles. Great relief that was the case, and greater relief to successfully get to Tebay chargers. Around 4-5 miles travelled on 0 miles left. I have no desire to repeat this experience.

Nothing I did seemed to halt the alarming haemmorraging of miles. The last 20 miles were spent at around 50mph but even that didn't seem to help. I think for every 3 miles real world travelled I was losing 4 miles off the GOM. This just would not happen with the S. I've puzzled about what went wrong here (other than my own error of not heeding the charge up warning). Maybe the wind was heavy against, also steep uphill in parts? Finally, the M3P had been acquired during lockdown and all drives so far had been very slow and low Wh consumptions. The real world miles travelled was also very low, so maybe the car hadn't got such a well tuned "history" to draw on, thus contributing to the problem encountered.

Do you have your own "I nearly ran out of charge" story to share?

 

[xdcthedoc]

Urghhh - horrible.

Had very similar happen to me once... was relying on the chargers in Pitlochry... only to find them out of order when i arrived and ended up driving 4 or 5 miles on 0 charge like you.

I also found the estimate for the last 10-20 miles to be wildly wrong despite me driving very slowly.

Very stressful and not a great advert for the E-driving experience. .

 

[davidmc]

To put this in context, I have owned my Model S for 2 years, and we have recently acquired a M3P for Mrs Mead. Had to go to Scotland last weekend, and as my S had a puncture, I had to take the M3P.

Now I completely accept that what ultimately unfolded was of my own making, but the contrast in range loss on the M3P compared to the Model S was disconcerting to say the least.

I set out from Scotland to travel back to Cheshire. Saturday evening, perfect weather conditions sunny and warm. Not sure about wind and direction and maybe it was strong against, considering what was to unfold.

I wanted to make the 260 mile trip with only 1 stop. I had just collected my elderly mother from hospital and wanted to get her back home with minimum charge stops. At Forth Valley Hospital near Falkirk the M3P said 202 miles range. 144 miles to Tebay charger was my plan. 56 miles to spare, no brainer I thought. What could possibly go wrong.

On approach to Gretna Services (last charge possible before Tebay) the car was giving the red warning not enough charge to reach destination without stopping at Gretna. At this point its 48 miles real world to Tebay and the car showing 63 miles. This was where I made my grave error. Extensive experience with my Model S told me there was no way I would ever not make it based on 48 miles and the car showing 63 miles. 15 'spare' miles for a 48 miler. It was unthinkable this could or would ever be a problem in the Model S. I concluded the M3P was being unduly cautious and it wouldn't be a problem. Bad mistake.

With 24 miles to go, the car showed 31 miles left. Still 7 to spare, ease off the speed, it will be ok.
By 12 miles to go the car showed 12 miles left. Really getting worried.
By 9 miles to go the car was showing 7 miles left. This isn't going to end well.
By 5 miles to go the car was showing 0 miles left.

All I can say is that for those of you familiar with the final miles to Tebay travelling South is that it is steep downhill for those last 2 miles. Great relief that was the case, and greater relief to successfully get to Tebay chargers. Around 4-5 miles travelled on 0 miles left. I have no desire to repeat this experience.

Nothing I did seemed to halt the alarming haemmorraging of miles. The last 20 miles were spent at around 50mph but even that didn't seem to help. I think for every 3 miles real world travelled I was losing 4 miles off the GOM. This just would not happen with the S. I've puzzled about what went wrong here (other than my own error of not heeding the charge up warning). Maybe the wind was heavy against, also steep uphill in parts? Finally, the M3P had been acquired during lockdown and all drives so far had been very slow and low Wh consumptions. The real world miles travelled was also very low, so maybe the car hadn't got such a well tuned "history" to draw on, thus contributing to the problem encountered.

Do you have your own "I nearly ran out of charge" story to share?

Glad you made it ok

One thing that seems to stick out to me in your mention above is that you had 3 passengers (including baggage?) in your car and on what sounds like a hilly drive? Maybe this would have contributed to the dramatic loss in range?

Never happened to me, but it may one day happen :/

 

[tsh2]

A/C running? I know my best long distance runs only achieve 85-88% efficiency (at around 60-65 mph, traffic constrained on the A1) in a SR+

It may be explained by a charge re-calibration (if you have been doing many short charging cycles over 50%, the BMS is only guessing what the actual SoC and range are).

I've not got this close to empty, but I find the trip energy extrapolation chart is good for showing what the trend looks like, and if you are beating the route planner estimate.

 

[Durzel]

I don't have any experience of this, but as above I wonder if this boils down to battery calibration (or lack thereof) ?

Presumably your S gets frequent use whereas the 3 - being newer and your missus's car - doesn't? Has there been a case before where you've driven it down to that sort of charge? If not, I wonder whether the range quoted to you was optimistic because the car simply didn't know any better, and as it went down in charge it was able to see that - actually - the percentage of battery left translated to far less miles than it originally thought, because it could actually see you were burning X percent battery for every Y miles travelled.

 

[Jeeves]

... Do you have your own "I nearly ran out of charge" story to share? …

Thankfully I don’t, but I’m glad you made it.

I get twitchy when I get below 10%, let alone something like you experienced. I switched to %charge instead of miles because the GOM seemed useless. I tend to use ABRP for quite conservative plans because I have no prior experience of another EV like you.

Loads of people I know wait for the fuel warning light to come on in an ICE car and seem to take pride in how far they can get on the vapours, a level of stress that I don’t require in my life.

@Durzel, what is this ‘battery calibration’ you mention? Might the %charge on my car be misleading?

 

[Durzel]

No, the charge % would not be misleading, but the predicted range might not be as accurate in a car that only ever does short journeys at high SoC vs one that regularly (or at least semi-regularly) drives for longer distances, using up more of the battery charge.

Perhaps "battery calibration" is too definitive a term, I didn't mean to imply there was an actual Tesla approved process as such.

 

[Jeeves]

Thanks. Just wanted to make sure I wasn’t missing a trick.

 

[TheManofMead]

Yes aircon was on...until grave concern kicked in and off it went.

There was only one passenger - my mother whom at 88 years is around 7 stone soaking wet. Plus her luggage - not much.

Durzel - agree prime supect is something to do with calibration.

In comparison, in July we roadtripped to Spain 3 in the Model S (70D) 3 adults plus luggage plus constant aircon. Fully charged the Model S shows 217 miles these days.

Bayonne Supercharger to Zaragoza Supercharger (around 198 miles) done comfortably starting with around 96% charge both ways.
Zaragoza to Valencia Supercharger (192 miles) also comfortable.

In both cases above arrived with around 10 miles still remaining on the GOM, so from a charge of 212 miles starting a loss of only (20 miles in one case and 14 miles in the other). Both of those journeys have some steep ups and down.

So (in rough terms) the Model S lost maximum 14 miles on a 198 mile real world journey.
The Model 3 lost 58 miles on a 144 mile real world journey.

 

[arg]

Yes aircon was on...until grave concern kicked in and off it went.
So (in rough terms) the Model S lost maximum 14 miles on a 198 mile real world journey.
The Model 3 lost 58 miles on a 144 mile real world journey.

Were you using the navigation system & predicted range, or just looking at the "fuel gauge" range? The sort of calculations of "50 miles to go, 20 spare" is what I used to have to do in the early days of Model S, but since the navigation-based range calculation appeared I always use that and find it so accurate as to barely need my own mental arithmetic as cross-check. Even if I know where I'm going (and perhaps disagree with the nav as to the best route), I usually put my destination in the nav for the range estimate.

The "fuel gauge" range is a fixed conversion from energy to miles, so does not take account of your driving style, tyre choice, weather conditions etc. So my suspicion here is that for your driving style in that car you will never get close to the range on the gauge - the fact that you were consistently losing range from the very beginning suggests it wasn't anything particular about this journey, it was the difference between the two cars.

You don't mention that you were fully charged at any of the points where you quote range figures: is it possible your wife's car is configured to show 'rated' range and your car is configured to show 'typical'? What do you see on the M3P when fully (or 90%) charged?

 

[CountvonC]

Glad you made it, I find the same with my M3P, 6k miles in 5 months and with that experience I know that I would never risk 144 miles on a 202 mile charge.

 

[TheManofMead]

@arg the most I have charged the M3P to is 90% which gives 278 on the GOM. So suggesting 310 at 100%. I thought the “fuel gauge” did adjust according to the history of your usage. Didn’t know it’s based on a fixed useage rate. I was just using the ‘fuel gauge’ as it’s always worked fine in the S. Finally I’m sure both the S and the M3P are configured to show the same (rated or typical) but not sure which as I dont/rarely go into that screen.

 

[MrBadger]

With 24 miles to go, the car showed 31 miles left. Still 7 to spare, ease off the speed, it will be ok.
By 12 miles to go the car showed 12 miles left. Really getting worried.
By 9 miles to go the car was showing 7 miles left. This isn't going to end well.
By 5 miles to go the car was showing 0 miles left.

By this stage, were you using the energy graph on trip mode? If so, what was that predicting?

 

[bhav]

I think moral of the story is don't use miles, use battery %.

That way (and in my view), you should do whatever it takes to ensure you're going to arrive with *at least* (say) 15% charge. It gives you a good enough safety net if the worst were to happen.

 

[TheManofMead]

By this stage, were you using the energy graph on trip mode? If so, what was that predicting?

No I wasn't. As I had gone beyond the point of no return (Gretna Services) I was accepting my fate at this stage and to be honest it never even occurred to me to look at the energy graph.

 

[anonymouse]

It would be interesting to know what ABetterRoutePlanner predicts if you put in the car model and details of the journey. Wonder whether it would have made a better stab at estimating?

 

[CyberGus]

Here's my true story (repost) about planning.

My first time using a Tesla was via Turo rental. I had an appointment 40+ miles away, and in-car nav pointed out I would return with -20 miles. There was a Supercharger nearby the destination, so I decided to take the appointment and charge before returning.

When I arrived, the SC was 12 miles away with 20 miles of range left, sweet! Unfortunately, the appointment ran long while a cold front blew through town. Now I had only 10 miles of range, and would come up 2 miles short.

My y-chromosome took over and said "no problem! we got this! I'll just turn off the seat heaters..." And off I went, confident that my mad driving skillz would deliver me to the promised land. Turns out that drafting is not very effective at 25 MPH, and driving "carefully" does not extend range.

8 miles to go, 6 miles of range left.
4 miles to go, 2 miles of range left.
3 miles to go, 1 mile of range left.

So now I'm wondering what I'll do with a disabled Tesla. Will it give me warning enough to pull over? Can a tow truck rescue me with a bucket of electricity? Buy 500 AA batteries? Long extension cord??!?

2 miles to go, 0 miles of range left.

I expected something momentous to happen, like a Start-Trek red alert klaxon blaring, or at least a "sad trombone" sound, but the wheels just kept turning.

1 mile to go, 0 miles of range left.

Maybe it'll just go slower as the battery dies, like a 70's Walkman? I was moving at the slowest speed that traffic would allow anyway, scanning the horizon for a Supercharger and wondering how far I could push a dead Tesla.

I never found out. I made it to the SC, despite having reached 0 range when still 2 miles away. Obviously the range is a calculated estimate, and/or they leave a small reserve for idiots like me.

Whew!

 

[TheManofMead]

It would be interesting to know what ABetterRoutePlanner predicts if you put in the car model and details of the journey. Wonder whether it would have made a better stab at estimating?

Just tried it out, using 65% (202 miles) as starting position. It suggests a charge at Gretna to add 16% and thus an arrival percentage of 17% at Tebay. Or alternatively you could say no stop at Gretna and 1% arrival.

I do recall setting Tebay as the destination at the start and it said arrive with 5% charge at Tebay. I briefly thought thats ridiculous it must be way more than that (again all based on / biased by my previous Model S experience). Virtually without exception in the S the predicted arrival percentage is always pessimistic and ticks upwards anything from 3% to 7% or more during a journey. Hence my misplaced confidence throughout.

 

[ArunG]

I would also go along with another person's comment of "a hilly drive". That area through the borders is definitely not good for battery or mpg in an electric or an ICE car.

 

[TheManofMead]

One thing I forgot to mention is that on plugging in at Tebay, before the charge commenced, the battery image on screen still showed a (very) small amount of red charge left (not that I would want to test how far it would have got me)!