Tesla Model 3 Unplugged – Summer edition

This is a follow up to my previous post about monitoring the phantom drain of my Model 3's battery as it sat parked for an extended period of time last winter.

Phantom Drain Summer 2019.png

Over 7 weeks this summer I remotely monitored the charge state of my car while I was away on vacation. During this time the state of charge dropped from 85% to 72%, meaning I saw not quite 2% of battery drain per week as the car sat parked in the garage.

The charge state was checked weekly using the Tesla app, thus allowing the car to remain at its low power sleep state for longer durations than during my last experiment when I took daily readings. I believe this explains why the drain was significantly lower this time around.

Car specification: Long Range Rear Wheel Drive Tesla Model 3, firmware version 2019.20.4, Sentry mode disabled.

Tesla Model 3 Unplugged – “phantom drain” when parked without plugging in

Despite Tesla recommending plugging their cars in when parking for extended periods I had to leave my Model 3 unplugged when I went to Sweden over the winter holidays.

Before heading to the airport I charged the car to 85% to make sure it wouldn't run flat. During my trip I tracked the so called “phantom drain” from the battery by taking a reading of the charge level every evening using the Tesla app.

Charge level vs. Day.png

After 42 days the charge level had only dropped by 28 points, to 57%. That's on average about ⅔ of a percentage point, or ½ kWh, lost per day. Based on this I wouldn't even worry too much about leaving the car unplugged for up to three months as long as I've charged it up beforehand. But plugging in while parked is of course always preferable as it lets the car run its battery management system.

An interesting data point to note is that one day after starting the experiment the charge level had increased to 86%. I suspect this was due to the battery recalibrating after the charging session.

Car specification: Long Range Rear Wheel Drive Tesla Model 3, firmware version 2018.42.4.

Environment: Unheated indoor garage in Seattle during December and January, temperature range 0 – 15°C (32 – 59°F).

Electric road trip from Seattle to Mount Rainier

In August 1919 a Detroit Electric EV made a promotional trip from Seattle to Mount Rainier. It's now 99 years later, and I decided to set out in a Tesla Model 3 Long Range to see if modern electric vehicle technology can do the same.


The goal of this trip was to see if it is possible to reach the Sunrise Visitor Center and make it back to civilization without getting stranded on the side of the road in the middle of the wilderness. Since charging infrastructure is extremely lacking around the mountain I took some precautions to avoid running out of juice.

The aero wheel covers were put back on the car to improve aerodynamics, the tires were pumped just past their recommended pressure to lower rolling resistance, and Chill Mode was enabled to compensate for my lead foot. I left downtown Seattle with the battery charged to 99%.

Click to enlarge map

Route and efficiency

The route I took included a detour to pick up my brother at Seatac Airport, and then to the Weezer concert at White River Amphitheatre, before ending the first day of driving at a hotel in Puyallup. There was no charging at the hotel, so early the next morning we set off up the mountain with battery capacity at 77%.

Tesla's navigation indicated that we would reach Sunrise Visitor Center at 1950 m elevation (6400 ft) with 30% remaining. Surprisingly we actually made it there with 41% remaining, having used 220 Wh/Km (353 Wh/mi) on the 114 Km (71 mi) drive from Puyallup.

While we enjoyed the views and mountain air for a few hours, we knew we were quite literally not out of the woods yet. Would the 41% battery be sufficient to get us to civilization?

Energy consumption went negative on the way down the mountain

Energy consumption went negative on the way down the mountain

We decided the next leg of our trip would be Route 12 south of the mountain, to the Centralia supercharger. As it turned out we needn't have worried about range. The regenerative breaking worked wonders on the way down and we arrived at the charger with 19% remaining in the battery, having used only 76 Wh/Km (122 Wh/mi) on the 195 Km (121 mi) drive from Sunrise Visitor Center.

Supercharging at Centralia, WA

Supercharging at Centralia, WA

After charging up at Centralia it would be no problem getting back to Seattle, so we declared the experiment a success at this point.

Road Trip Statistics

The stats for the full drive Seattle > White River Amphitheatre > Puyallup > Sunrise Visitor Center > Centralia ended up being 417 Km (259 mi), using 80% of the battery at a reported 133 Wh/Km (214 Wh/mi).

These reported consumption numbers look a little dubious to me. Assuming a battery capacity of 75 KWh the 80% utilization over 417 Km (259 mi) should be 144 Wh/Km (232 Wh/mi). I don't know how to account for this discrepancy unless losses while parked are excluded from the reported numbers. We did see 2% phantom drain during the hotel night, perhaps there was more drain during other stops along the way that I didn't notice.


I am frankly a little surprised at the reported efficiency figures we achieved during this trip. In my day to day driving I usually see reported consumption of 150 Wh/Km (240 Wh/mi). We did use air conditioning, but didn't speed or drive aggressively. I suppose the low speeds of the mountain roads helped avoid drag.

Something I hadn't considered before setting off was the lack of AT&T connectivity in the area. This lead to the car's navigation system being pretty unusable for the trip down the mountain until we found a spot with signal. Luckily I had brought a physical map. My brother's T-Mobile connection was superior to AT&T, so we could also use his phone as a navigation fallback.

Instead of heading straight for Seattle we decided to extend our road trip to the Pacific ocean, setting our sights on Westport where we were delighted to find the Cranberry Road Winery, which had a Tesla destination charger.

Destination chargers at the Cranberry Road Winery

Destination chargers at the Cranberry Road Winery

Referral code

If you are considering buying a Tesla car or solar panels you can use my referral code "kim33408" to sweeten the deal. Details on the linked referral page.



Icons used in route map graphic; "buildings" by Blair Adams from the Noun Project, "Airport" by Melissa Ambroso from the Noun Project, "Hotel" by Gan Khoon Lay from the Noun Project, "Mountains" by Alice Noir from the Noun Project, "charging" by Jared Ng from the Noun Project