The Tesla plug adapter and my longest drive

When I bought the 2017 BMW i3, I found myself visiting Napa Valley (about 100 miles away) every other month. I had friends that would join me on occasion which made the trip more fun. I discovered there were DC-fast chargers installed in three locations in the valley along my route and I could recharge for my trip home in about 40 minutes. I also found level-2 chargers at several of the wineries in the area, and sometimes I would add one of those wineries to my itinerary just to take advantage of the charging, getting my car juiced while I got juiced.

One day I was shopping on Amazon and found an adapter that allows me to charge the BMW i3 using a Tesla destination charger. I knew this would open up access to more of the wineries with only Tesla chargers, as well as some hotels. The price wasn’t too steep, and I could store the adapter in the i3’s “frunklet” (a tiny front trunk area that holds the level-1 charger and tire repair kit). Shortly after I received the adapter, I headed to a local Tesla destination charger and plugged in my car. It worked. Now I have a plan-B for when I’m traveling. This would soon come in very handy.

On one of my next trips to Napa Valley, I decided to visit one of the few Zinfandel producers remaining in Napa. (Most wineries converted to Cabernet Sauvignon because of its success there.) Storybook Mountain Vineyards lies at the northern end of the valley, which is furthest from my home to the South. I plotted the route in Google Maps and the distance was 126 miles. Driving conservatively, I knew I could make it there without charging, but I couldn’t go much further without plugging in. Storybook Mountain Vineyards was listed as a winery with an EV charger, so I could charge there before heading back. (My tasting appointment didn’t allow me enough time to charge en-route.) When I arrived at the winery (with 14 miles remaining), I noticed the EV charger was a Tesla destination charger. I nervously connected the car and adapter to the charger and the car started charging. I relaxed and enjoyed my wine tasting experience and ate a sandwich afterward. The 90+ minutes boosted my charge enough to drive almost 50 miles, so I had plenty of electricity to complete my winery visits before charging up at the DC-fast charger on my way home.

One-pedal-drive and the brake lights

When driving any car, as you apply the brakes using the brake pedal, a switch connected to the pedal is “closed” and the brake lights are turned on. The point of this is to signal the driver directly behind you that you are slowing down. This signals the following driver to also slow, or change course, to avoid a collision. (I once had to repair the switch in my brake pedal and learned a little about this.) Similarly, when stopped, keeping your foot on the brake makes it clear to other drivers that you are stopped on the road so they can prepare to stop.

After driving my new BMW i3 for a while and adapting to using the one-pedal driving technique, it occurred to me that I didn’t know what was happening with the brake lights when I would slow down or stop (using the regenerative brakes). At first, I tried watching other i3’s around me to see that their brake lights came on (and they did), but I couldn’t tell whether these drivers were using the brake pedal or just the regenerative braking from the motor. I tried applying the brake pedal while coming to a stop (to ensure the brake lights lit), but that made my stops jerky and uncomfortable.

Finally, I figured out a way to learn more about how the brake lights were activated. The Ford F-150 sometimes comes with a large, “chrome” grill. When one would pull up behind me as I approached a red light, I was able to check my reflection in the grill to determine when my brake lights would be on. I learned that once the regenerative brakes are engaged roughly 40% or more, the brake lights come on. They stay on until the car comes to a stop (because the “brakes” are no longer engaged). So, if I slow gradually, the brake lights stay off. If I brake abruptly, like approaching a traffic signal, the brake lights stay lit until the car stops. For many safety reasons, I have learned you should keep your foot on the brake pedal while stopped at a traffic signal. This prevents the car from rolling and signals the cars behind you that you are not moving.

Learning to drive “one-peddle driving”

Anyone who has learned to drive a stick-shift car will tell you it takes a little while to train your feet to manage the clutch work, braking, and accelerating when you first start. With an automatic transmission, there is no learning curve like this. With an EV, there is just one speed (gear) so there is no need to shift. In the Mitsubishi i-MiEV, the (software) engineers managed to emulate the behavior of a gasoline engine coupled with an automatic transmission. Namely, when your foot is off the gas and the brake, the car will propel itself at very low speed. This is especially useful when backing into a driveway – just start moving, take your foot off the pedal, and let the car “coast” into position. The BMW i3 changed all that.

When my brand new 2017 BWM i3 first arrived, I took it out for a spin around the block. The first thing I noticed was that taking your foot off the pedal caused the car to come to a stop. This makes sense because regenerative braking is slowing the car, and bringing the car to a stop maximizes the energy generated. It didn’t take me long to adapt to driving forward like this. I quickly learned how far back from a stop sign to remove my foot and let the car come to a stop on its own (except downhill). The trick was trying to back up. All my (driving) life I had learned to back up by providing a pulse of motion, then allowing the car to coast backward until I was ready to stop, when I’d press the brakes. That’s not how it works with one-pedal driving. In order to coast in a car that employs one-pedal driving, you need to train your foot to learn the pedal position of the neutral spot, where neither acceleration nor braking occur. (This is similar to learning the spot in the clutch travel where the transmission engages.) Before I learned where this spot was, I would give the car a nudge to start moving, then remove my foot from the pedal and the car would stop right away. This was confusing and frustrating. (I have a 60-foot driveway and it took about five tries to back up all the way to my garage.) Once I learned the neutral spot in the gas pedal, I was able to nudge the car into motion, adjust my pedal to the neutral position, and allow the car to coast into position. Then I simply remove my foot from the pedal to stop. This technique has now become second nature to me. So, which style of driving do I prefer? With a gasoline engine, I have always preferred a manual transmission with a clutch. You have much more control of the speed when driving through the hills. Between the Mitsubishi and the BMW, I find I much prefer the i3’s one-pedal driving to the i-MiEV’s. You actually have more precise control over when the energy is applied to or removed from the drive wheels, giving more precise control in the hills. And because the car has rear-wheel drive, using the motor this way for braking does not rob traction from the front wheels the way that the brakes do. I am hopeful that all of my cars in the future will also provide an option to use one-pedal driving. On top of the driving dynamics, it reduces brake pad wear dramatically (which also reduces the metal particle emissions during braking).

What became of the purple i-MiEV?

After I had my fun in the tiny Mitsubishi i-MiEV, I passed the car down to my other half who would drive the car each day to work, to family, and home. The daily round-trip was 20 miles. Charging would be needed every other day. Since we shared one charger at home, I would have to plan my charging for the days he would not need to charge. Because I could easily go four days without charging my BMW i3, this was not usually a problem. On occasion, I would plug in the i-MiEV at 9:00pm. It would finish by 2:00am when he was leaving for work. I’d have him plug in my car as he unplugged his car and I’d have a full charge by 7:00am.

Just as had happened with me, the characteristics of the i-MiEV motivated my partner to opt for driving surface streets rather than the freeways. The i-MiEV was based on the Japanese Kei-car requirements, which limits horsepower to just 63 ponies. Around town, that much power is more than ample, but pulling onto the freeway was a real task for the little car. As I had noticed before, he found driving on the streets seemed more relaxing than taking the freeway. On the freeway, everything is rushed, and you sense this as you drive. On streets, you’re traveling slower and notice more details of your surroundings. Plus, the instant torque means you have an advantage at each traffic signal to leap ahead of the other cars.

Together we managed to accumulate nearly 80,000 miles in the i-MiEV. When the time came, I sold the car to a family in Santa Cruz. They already had an early electric Fiat 500e and were hoping to get a four-door EV to accommodate their teen-aged kids better. Towards the end of our i-MiEV’s journey, the car wouldn’t charge. I tried at a ChargePoint charger to determine whether it was my home charger at fault (it wasn’t). So, I took the car to the local dealership. They needed the help of a remote diagnostic tool and the engineering team in Japan to isolate the problem. Six months (and two service managers) later, I received a call that the car was now repaired and ready to take home. I was dreading the repair bill, but Mitsubishi covered the cost of the repair. It was the happiest possible ending to the longest lasting repair that I have ever experienced. I sold the car just a few months later and used the new charging controller as a selling point.

How to end daily range anxiety

 So, driving a small electric car with a tiny (16KWh) battery almost forces you to think about and plan every mile you intend to drive the next day.  If you’re not able to complete your trip within 55 miles (round trip), choose a car with more range (e.g., a gasoline powered car).  Those were my choices while I drove my 2012 Mitsubishi i-MiEV.  For the most part, my commute and errand runs all fit within that range, so my daily range anxiety was limited, although ever present.

My 2012 Mitsubishsi i-MiEV

That all changed when a couple of unexpected things happened.  First, BMW released a larger battery pack for the 2017 i3 (32KWh instead of 22KWh), which increased its driving range to over 120 miles.  While I wasn’t a fan of the car’s looks, the larger battery would mean I could take the i3 to many more of the places I visit more or less each month, and fast charging would nearly double how far I could easily drive in the car.  The i3 was also one of the few rear-wheel drive electric cars available when I was ready to buy.  As for the second unexpected thing, a robotics startup that I had worked for ten years ago had been acquired by a larger tech company, and all the shares of stock I had been granted were now going to be worth something… enough to pay for 20% of the car.  BMW was also offering a big financing incentive, so I got a loan too.  I picked out a 2017 BMW i3 electric in Protonic Blue.

My 2017 BMW i3 when it was delivered

After about a month driving the i3, I noticed that my daily range-anxiety had dramatically diminished.  I could commute four days without recharging and have plenty of range remaining when I finally did plug in (15-35 miles).  I could drive to work, visit my mom after work, drive home again, and still have enough charge for the next day.  What really shocked me (ha ha) is that the BMW i3 was averaging 5.3 miles per kilowatt hour, while I only measured 4 to 4.5 miles per KWh in the Mitsubishi i-MiEV.  On top of that, the BMW was bigger, heavier, and more powerful, all while using less energy to propel itself.  Now the range anxiety shifted to my monthly longer drives.  I could now drive roundtrip between San Jose and San Francisco on a single charge (75% to 80%).  But the best part was finding the DC-Fast chargers in Napa Valley, which meant I could visit all of my favorite wineries and recharge for my trip home.  The biggest concern on my Napa trip was driving into the wind on the way home, which really used up the charge.  Even so, I was able to make it home with more than 12 miles to spare.

By 2023, 200 to 300 miles of range had become the norm for electric cars.  With that much range, many more places would be accessible (round-trip) on a single charge, and a drive from San Jose to Los Angeles would involve a single charging stop along the way.  That kind of range nearly eliminates range anxiety for almost all except for the few long-distance road-warriors and long-distance trailer-luggers that are probably still better served by a gasoline-powered car.

Gone with the wind

Walking into the wind takes a little extra effort than walking in still air.  Walking into a strong wind takes a lot of extra effort.  Bicycling into a strong headwind really slows you down, and that’s only at a speed of about 15 to 20 miles-per-hour.  So, you can imagine my surprise at how quickly the power depletes from my car’s battery while driving down the freeway into a strong headwind.  At first I thought that maybe the tires were a little low and in need of a good pumping up.  Then I looked at the tree tops.  (The palms are a dead giveaway.)  The top branches were swaying in the wind, suggesting a strong wind was working against me. 

How big is the difference in energy consumption driving into the wind?  Normally, my drive from home to the exit I would usually take for work (and to visit mom, and to drive up to the winery) uses about three ticks of energy on the gauge.  Driving into a strong wind, I noticed that the energy used at any moment to maintain speed was slightly higher, but shortly after taking my exit, I noticed the forth tick drop off.  I cover a distance of about 13 miles, suggesting that the extra wind load uses about 20% more energy.  Considering that the battery performs a little worse in colder weather (such as typically happens with a strong wind), I would attribute about 10% to 15% of the extra 20% power drain to the wind itself.

The impact of this extra power drain is more significant than it seems, especially for freeway trips.  Under better conditions, my now four-year-old battery can travel about 58 to 62 miles on a charge, mostly on the freeway.  If I am driving into a strong headwind, that range drops to 49 to 56 miles.  Even when I was working in Palo Alto, the 49 miles was enough to get me to work and back, and a quick trip for tacos nearby for dinner.  But, if I had planned to visit the wine store (an “errand”) in Redwood City during lunch, then that would add another 12 miles to my trip, meaning that I would be at risk of not making it home from work on a windy day.  When the battery was newer, the range was closer to 70 miles, and even a 15% drop in efficiency would still get me to the wine shop and home.

Charging atop a mountain

After losing my job due to a company layoff, and while searching for work (a full-time dedication for an older engineer), I found myself missing the moral support of coworkers (and a paycheck).  So, I decided to apply for work at a winery that was only open to the public on weekends.  This would mean that I would have the option to keep the job even after I resume my career, allowing me to build my experience working in the wine-hospitality industry.  The winery is atop the mountains in Cupertino at an elevation of 2,200 feet.  (Home is a mere 100 feet above sea level.)  The winery also has a level-2 EV charger available to employees.  Having driven to the winery twice before, I knew that the EV charger would be a comfort more than a necessity for getting up and back on one charge.

My prior experience driving up the mountain suggested I would use one-half of the total charge to drive up the mountain.  I would also regenerate about 10% coasting back down the hill, allowing me more than enough power to make it home (and to the store).  So, on my third trip up the mountain for work, I learned about charging atop the mountain.  I had only driven about eight miles the day before and decided not to recharge before driving to work.  When I got to work, the power level was lower than I am usually comfortable with, so I plugged in the car (just towards the end of my shift).  By the time I had disconnected, there was just one bar remaining (out of 16) to be filled, and I knew that the remaining energy would be generated while braking on the trip down the mountain.

Apparently, the engineers at Mitsubishi had anticipated my very situation and had to prioritize the survival of the charging system.  Once the car’s battery is nearly full, most EV chargers will send less current to the car (as observed using the ChargePoint web site dashboard).  It would seem that this is at the request of the car, not the charging station.  While driving downhill, this time I noticed that the amount of regeneration happening was a fraction of its usual potential.  It dawned on me then that the same battery-protection logic had kicked in and the battery was accepting less charge from the brakes.  That meant that I had to work harder using the friction brakes to slow down the vehicle.  As the charge level approached full-charge, the regeneration brakes were almost completely ineffective and I was relying almost entirely on the friction brakes.  While this is only a minor problem, the biggest concern is having to take the turns more slowly because the friction brakes act on all four wheels, while the regeneration affects only the rear wheels, allowing the front wheels to dedicate all friction to traction in turns.  (Only the Tesla and BMW share this rear-wheel drive configuration with my Mitsubishi – all others are front-wheel drive.)   

So, what have I learned from this experience?  I have to time my charging carefully when atop the mountain.  I estimate the time needed to attain a full charge (say about four hours), then I deduct an hour from the charge time and start a timer on my phone.  When the timer’s alarm goes off, I dash out quickly to unplug the car.  This leaves me with just enough empty battery capacity to run the regenerative brakes nearly all the way down the mountain.  (In the winter months, I soon learned that I could drive down the mountain in toasty comfort by channeling excess power generated by the brakes into the cabin heater.)