A Tale of Slow, Cold, Supercharging

[bdogmac]

I own a Model 3 Long Range, Dual motor. On Thanksgiving day I traveled from Montclair, NJ to Schenectady, NY (about 157 miles). I had the aero covers on the 18” wheels, and the tires were a hair low at 41psi. My wife, two small children and I departed about 7:15a and it was about 18°F. The night before departing, I attempted to charge the battery up to the full 310, but for some reason (the cold?) was only able to get it to register 300 miles on the battery. I do not have a garage, so the car was outside. I was using a 12A/120v UMC up until the time we left. I had preheated the cabin to 68° while still connected to shore power. My wife kept her seat heated on the medium (2nd?) setting while I had mine set for low, we kept the cabin at 69°. We drove, not very aggressively at about 70mph or less, using Autopilot and Navigate on Autopilot most of the time, 98 miles to the Kingston, NY Superchargers (120kW). By this time there were about 150 miles left on the battery indicating to me that we were paying about a “50% cold tax” (ie. 100 real miles but lost 150 miles off the battery). There was no one else at the chargers when we arrived. I parked in a sunny spot and plugged in. The charger ramped up to 35kW and sat there. On the downside it was still about 18°F outside, but on the upside I had be driving 65+mph for the last 90 min (= warm battery?). After about 5 min another model 3 pulled up and parked about 4 spots away. I asked the driver how fast his car was charging and he showed me his phone and it was 65kW (he said he had come from Summit, NJ, about the same, if not slightly farther, distance that I had come.) I then unplugged and moved my car over about 6 spots and tried again, still getting only up to 35kW. A few minutes later, the other Model 3 owner departed, so I unplugged again and went to the exact same charger he was on, plugged in and it ramped up to 35kW. I stayed there for about 5 minutes, but no change. I do not recall what the “Current Charge” setting on my screen was showing, but I do recall that it was greyed out – as if I was not able to make any adjustments (preferably upward.) My mistake in not taking a screen shot.

For the 4 hrs at my in-laws’ house I kept the car plugged into 120/12A via the UMC – still about 16°F outside. We preheated the cabin while on shore power and pretty much all the variables were still the same. At about 5p we drove 15 miles to the Crossgates Mall Superchargers (120kW) and plugged in there with about 120 miles on the battery indicator when starting to charge. I parked far from the only other Tesla at the 20 stalls. This time the charger ramped up to 65kW, but no higher even though I was charging for 45 minutes. Thankfully the ride home was uneventful with the cold tax of 50% still holding all the way home.

In addition to the potential questions regarding the maxing out at 35kW and 65kW, and the cold tax, I wonder if using TACC, Autopilot, and/or Navigate on Autopilot improves or erodes efficiency. And I wonder since I was driving a mostly constant speed, and not a bunch of accelerating, if the battery can get cold even though the car is going 65mph.

Thoughts?
Thanks.

 

[Big Earl]

Autopilot and TACC are less efficient than driving carefully on your own. Both tend to accelerate and slow down more rapidly than an attentive driver would, especially in traffic. Chill mode helps, but driving it yourself can save energy in a pinch.

I think you probably have gotten a full speed charge if you had charged in Albany or Guilderland instead of Kingston, as the extra driving time would have added more heat to the battery.

A Better Routeplanner suggests that you'd arrive at Guilderland with 34% remaining. If it was going full speed, a 17 minute charge would have gotten you to your destination with 60% battery remaining.

I've found it's also helpful to give it a good full acceleration run from a slow speed to a high speed, followed by regen back down to a slow speed before pulling off the highway to Supercharge. This will create some additional heat in the pack that can be beneficial for charging speed.

Finally, I much prefer to have the battery level displayed in % instead of miles. For determining range, use the energy application to monitor consumption and to see the car's projected remaining range based on your recent 5, 15 or 30 miles of driving.

 

[TexasEV]

I own a Model 3 Long Range, Dual motor. On Thanksgiving day I traveled from Montclair, NJ to Schenectady, NY (about 157 miles). I had the aero covers on the 18” wheels, and the tires were a hair low at 41psi. My wife, two small children and I departed about 7:15a and it was about 18°F. The night before departing, I attempted to charge the battery up to the full 310, but for some reason (the cold?) was only able to get it to register 300 miles on the battery. I do not have a garage, so the car was outside. .

Yes, the reason is batteries have less capacity when they're cold. It's one of the many reasons that EVs have less range in the cold.

I wonder if using TACC, Autopilot, and/or Navigate on Autopilot improves or erodes efficiency. And I wonder since I was driving a mostly constant speed, and not a bunch of accelerating, if the battery can get cold even though the car is going 65mph.

No to the efficiency loss. The problem is cold air has greater density, it takes more energy to push through it, and tires have more rolling resistance in cold.
Yes your battery can still be cold when driving in 18 degree weather even when going 65 mph.

 

[mswlogo]

If your battery is near 50% it just won’t charge that fast and your battery was still probably pretty cold.

Using 120V charging in below freezing temps will be painful.

I drove 70 miles the same cold night before. Battery at 20% and probably not quote as cold. It just lost all dots of reduced regen about 10 miles earlier. So battery was still probably not completely warmed up.

It charged at 110 kw.

The last 4 weekends with warmer conditions (35 F) and 50% battery it refused to go above 50 Kw.

SOC seems more critical than the temperature. But you need to be pretty low on battery and warm battery to get the high charge rates.

 

[ewoodrick]

First, Superchargers have pairs of pedestal. There's an A and B for each number. It doesn't matter where you park, next to, or long way away, you have to look at the pedestal number. If you plug into 3, you need to see if the other 3 is in use.

Your issues are probably a combination of many things.

It's cold outside, everything is slower. ICE are often plugging in, just to keep their block from freezing.
You don't get the high current charging when the battery is full, It starts at full and starts rolling off earlier than some folks think.

Let's put something in a test chamber and cool it to 15 degrees and then blow 15 degree air over it at 70 mph. How much energy would be needed to warm it up to over 50 degrees? Well, that's what's happening to your battery.

Preheating the interior doesn't take much energy or time. Keeping it heated for 15 minutes takes a lot more. If you want to be energy efficient, turn the heat down more and keep the seat heaters on. Honestly, 69 degrees and seat heaters is possibly about the most inefficient that you can get. If you get that car warmer, you don't need the seat heat.

If you want to charge fast, use more battery.

And did you have the 18 inch wheels and covers on?

 

[xilex]

At 55%, supercharging for me is 40 kW. This is at urban supercharger that is rated 72 kW. In 75 degree weather. So probably you had plenty of battery left when charging.

 

[suwaneedad]

OP, looks like an ~8% cold tax to me. 150mi of range used to travel 100mi at highway speeds implies a 33% total tax (not the 50% stated). And at highway speed, my experience has been a ~20% range tax applies (uncovered aeros in moderate/warm/hot weather in my case). So that'd mean you paid an incremental ~8% range tax due to the cold temps. That seems remarkably reasonable to me, although will continue to be an issue as Model 3s go mainstream to first-time EV owners in cold climates.