Important lesson learned. Don't trust Tesla routing for Superchargers

[Gnaget]

I've had my car for 4 months now, and I finally had an opportunity to give it a real test. Drove it 120 miles, 240 mi round trip + dog mode all day. On the return trip back, I had about 100 miles of remaining range, and so it routed me to a super charger 80 miles away. This gave me 5% estimated battery life when I arrived at the supercharger. Felt a bit close, but I figured Tesla would know better than I.

I get on the highway, and within a few miles I see that estimated battery life drop from 5 - 4 - 3 - 2. I quickly decide it isn't worth risking it, and decided to manually route myself to a closer supercharger only to find out there wasn't another one between where I was and where I was going to. I turned around and went to the one where I left from, 10 miles backtrack.

So why didn't it just tell me to go to that supercharger to begin with? The other one was a risk, and I only needed to charge to 50% to get to my destination. As a new owner, I trusted Tesla software over my own intuition, and it almost resulted in me being stranded at night in the middle of nowhere.

On a side note, supercharging is cool. That was my first experience, and while I knew it was crazy fast, I wasn't expecting this fast. Seeing a charge rate over 900 miles / hr was fascinating. It was like having an entire substation's power dumped into my car. I went to a drive through to eat in my car while it charged, and I didn't even have time to eat it all, or finish a youtube video I put on.

 

[rhumbliner]

So why didn't it just tell me to go to that supercharger to begin with?

Tesla can factor in elevation change but not wind or vehicle speed. What was your speed relative to the limit or flow of traffic? Did you have a headwind? I assume temperature wasn’t a factor since your drive was done recently. I also assume you weren’t pulling a trailer or have something mounted on the roof?

 

[LoudMusic]

It is strange it decided to send you to a charger where it already expected you to arrive at 5%. Previously I believe it would try to have the car arrive with 10% but more recently I've been seeing 20%.

But the dropping arrival percentage is a different issue. That's usually due to unexpected conditions. The biggest being drive speed. Air resistance is exponential as speed increases. Beyond about 50mph, every 5mph you add the consumption goes up dramatically. The car initially bases estimates on speed limits then adjusts based on recent driving habits.

 

[kgvickers]

I've had a 2019 M3P since September 2019. I've made a lot of trips from Fort Worth, TX, to North Carolina on i20. My experience is that the Tesla routing has improved a lot in the last 3 years. I don't just automatically trust it - I always do a quick sanity check if I know it's going to be tight. I use the calculator app on my iPhone, and I know roughly what my usable battery capacity is.

If I want to drive really fast, say 85, then I've got to expect to consume 300 - 350 watt/hr per mile. If I want to drive the speed limit, typically 70 for that route, then the consumption is considerably less. In good weather it might be as low as 250 watt/hr per mile.

I always get better economy than my wife, doesn't matter what we're driving. She's always punching a pedal, the go pedal or the brakes. Even if we average the same speed overall, the constant acceleration/braking really eats battery.

 

[Gnaget]

Tesla can factor in elevation change but not wind or vehicle speed. What was your speed relative to the limit or flow of traffic? Did you have a headwind? I assume temperature wasn’t a factor since your drive was done recently. I also assume you weren’t pulling a trailer or have something mounted on the roof?

nothing unusual. The highway was 70, and my speed was set for 75

 

[fholbert]

I always get better economy than my wife, doesn't matter what we're driving. She's always punching a pedal, the go pedal or the brakes. Even if we average the same speed overall, the constant acceleration/braking really eats battery.

Pretty sure I followed her for about 30 miles today.

 

[fholbert]

I get on the highway, and within a few miles I see that estimated battery life drop from 5 - 4 - 3 - 2. I quickly decide it isn't worth risking it, and decided to manually route myself to a closer supercharger only to find out there wasn't another one between where I was and where I was going to. I turned around and went to the one where I left from, 10 miles backtrack.

Sounds like range anxiety to me.

You never said it wouldn't have made it to the 1st Supercharger.

Everyday I set my cruise for 79mph for 48 miles one way, I leave at 3:30am. When I get to work my % at destination has gone up 2% to 3%. Coming home, at noon traffic is a little heaver but I average about 65 MPH. Same thing, the range at destination is increasing about 2% by the time I get home.

 

[Big Dog]

nothing unusual. The highway was 70, and my speed was set for 75

Surprised the computer did not tell you to reduce speed to make it to yoru destination. (I've had it tell me to keep below 65 to make it to the next supercharger.)

But yeah, 75+ is gonna suck electrons.

 

[Silicon Desert]

The title was a bit misleading to me. I guess it is not the routing that is a problem. It is the prediction of where to charge. I misunderstood you were implying that routing is an issue.

I guess it is just me, but just like with my old ICE car, I NEVER like to cut things that close. Ya never know when some unknown issue crops up along the route.

 

[LoudMusic]

Surprised the computer did not tell you to reduce speed to make it to yoru destination. (I've had it tell me to keep below 65 to make it to the next supercharger.)

But yeah, 75+ is gonna suck electrons.

I'm curious about this too. Did it recommend slowing down to reach your destination?

 

[electrikcuban]

I've seen my estimated arrival state of charge drop from 15% to 2% after I have my wife drive the car.... she drives it like it's an ICE car. No regard for economy. Still made it, and never had the car tell us to slow down.

 

[Takumi]

My problem's the opposite. Tesla recommends stopping at a closer supercharger where I'll be charging for 5-10 min. I look at the map and the next supercharger will be exactly where I need the SOC to be - between 10% - 20%. Maybe there's a setting in there that I haven't looked? But my strategy for long drives is to speed up, draft, or slow down as necessary to get the estimated state of charge where I want it to be.

 

[Silicon Desert]

My problem's the opposite. Tesla recommends stopping at a closer supercharger where I'll be charging for 5-10 min. I look at the map and the next supercharger will be exactly where I need the SOC to be - between 10% - 20%. Maybe there's a setting in there that I haven't looked? But my strategy for long drives is to speed up, draft, or slow down as necessary to get the estimated state of charge where I want it to be.

yea I have occasionally had that happen, but not often for us.
You mention "draft", as in drafting another vehicle? Hmmm, something I never do. Consequences too great.

 

[Takumi]

yea I have occasionally had that happen, but not often for us.
You mention "draft", as in drafting another vehicle? Hmmm, something I never do. Consequences too great.

I haven't done it recently, but I did it unintentionally with the 2016 MS. Didn't care to pass a truck when it merged into our lane. IIRC, I had it set to a following distance of 2 or 3. I only noticed it was doing something because the estimated SOC kept climbing up. Then a rock hit the windshield. No damage, but it was enough for me to make the decision to at least get in front of the truck. That circumstance did tell me that was one of the cards I could play if needed.

For the most part, slowing down or speeding up does the trick. Daily driving the LEAF did prepare me to take EVs to a low SOC.

Before the superchargers were this ubiquitous, I used to manage the HVAC manually too.

 

[posity]

I view the suggested chargers as merely that: a suggestion. I always do the 'show Superchargers' voice command and look at alternate scenarios, then manually pick the superchargers that I will use. I also keep checking how busy they are to get an idea of the chances a particular location will be full when I arrive.

In the end, I probably only use the suggested superchargers about half the time. Now that there are so many supercharger locations, the routes I take and the superchargers I use frequently have multiple ways to plan a trip.