The other day, a Tesla Model 3 driver stopped by to top off his charge while visiting some nearby relatives. It was VERY cold out (-20℉ when I woke up…) The car charged at 40 amps, and I thought I’d film some THERMAL VIDEO of the car charging out in the cold!
I’m on Plugshare, which is a way of sharing and finding electric vehicle charging stations, whether commercial or private. I got a text message from Marc, who was hoping to stop by to charge his Model 3. I normally charge with a 16A Amazing-E EVSE, but would want to be able to charge the 3 faster than that! I also have a 32A GE EVSE on the other side of the garage. That with the snap-on Tesla adapter would work fine. But best of all was that I also happen to own an older Tesla universal mobile connector. That’s a very compact, portable, EVSE for Tesla which can plug into a 240V 50A electric outlet. I simply unplugged my daily charging cable, and plugged in the Tesla connector in its place.
Marc pulled up with his car, and we plugged him in. After a brief tour of my solar array and EV projects in my garage, he headed out with relatives in a different vehicle to spend the afternoon at a local lake cottage. Before leaving, he offered to pay for my electricity. When I refused it, he asked if I drink beer, and I said that indeed, I do.
The car was charging at 40A. Modern electric cars have all sorts of information on the display or on a phone app. My Mitsubishi iMiEV is more basic, so I had added a multimeter to the 50A electric outlet in my garage. I was able to track how much power and energy the Tesla used, even without looking at the dashboard or an app. It drew a fairly steady 40A for the entirety of the 3 hours the car was plugged in.
When we first plugged in, the solar array was producing 10A – a solid 25% of the power being used to charge the car! Unfortunately, the sky clouded up not too much later, so the solar energy to the car ended up being relatively low.
After charging for a good hour or so, I pulled out the thermal camera to take a look at what heat was being created and where. I’m shooting thermal images with my FLIR ONE smartphone attachment (https://amzn.to/2S90ZRv)
I started at the 50A electric outlet. That was a nice clean connection with minimal heat. Next, I looked at my “Remote Box” – a switch, contactor, power/energy display, and NEMA 14-50 electric outlet. I was surprised at how much heat was being produced right in the middle of it. That’s where the contactor is, and the full 40A would be running continuously through it. I later looked up my original order and the specs of that component. It is rated at 40/50A, so it’s the right part, but it might not hurt to have purchased one with the next higher rating.
The plug of the Tesla universal mobile connector was also rather warm. I expected that, as the end is detachable to swap between a standard electric plug and a NEMA 14-50. Being detachable means another set of contacts in close proximity to the blades that plug in to the wall.
The cord itself was slightly warm.
When viewed in thermal video, the cord stood out in stark relief against the colder concrete. In fact, I could even move the cord and see the heat after-image on the concrete of where the cord had laid.
I headed outside to take a look at the car.
The cold outside air easily dissipated any excess heat from the cord. The Tesla end of the cable looked warm, but really didn’t feel that way. The thermal camera essentially uses an auto-iris, so the warmest areas in an image are red, even if they are only a few degrees above zero. That means that the sunlight – even making something a degree or two warmer than other areas, can very much change the look of the thermal video. That’s one reason why I use the on-screen thermometer to be able to spot check the temperature in the middle of the screen.
Viewing the rest of the car with the thermal camera, I was hoping to find particular hot or cold areas. Unfortunately, I did not. I know that there is an active fan and radiator on the front of the car, but didn’t notice anything in particular. The front of the car looked slightly less cold, but that end was also facing the sun, so it’s hard to be sure.
One friend on Facebook said “Wait, you are PAYING for somebody else to use your electricity!?”
I sure was! Sharing an electric outlet is a great way to build good will and meet new and interesting people. But how much was this costing me?
I took a photo of the kilowatt-hour meter before the start of charge, and after the car was unplugged. Going from 189kWh to 218kWh means that the car used at least 29 and no more than 30 kWH. That’s the financial cost equivalent (at $0.13/kWh) of $3.77 to $3.90. I also checked later in the day and found that the solar only produced 3 kWh in that same time, subtracting a mere 39 cents from my bill! Charging somebody else’s Tesla still cost me $3-$4!
A while later, the owner returned. I heard a *clink, clink* on my front porch as a package was dropped off. I headed to the front door, grabbed my coat, and went outside to put away the charge cord and say good-bye. Just as Marc left, it started to snow.
Back inside, I had my fireplace cranking away. Nothing beats the super-cold temperatures like roaring wood heat and 75 degrees in the living room. The mysterious package turned out to be a paper bag six-pack of bottled Milwaukee Brewing Company beers. I’m not sure of the exact economic cost of the six-pack, but it’s certainly more than the addition to my electric bill.
So, I get to make new friends, learn more about charging at higher currents with electric cars, AND drink a beer.
Life is good.
Until next time, stay charged up!
-Ben
