No More NissanConnect

The 1st gen Nissan LEAFs came with a 2G Telemetry Unit (TCU), which is a cellular modem that allows the car to talk to the Nissan Connect/CarWings backend. This gave some neat features like being able to remotely poll the charge level, start/stop charging (if plugged in), and perhaps, most importantly, remotely trigger the climate control to preheat/cool the vehicle before you get into it. The latter is especially useful in the coldest winter months where you want to be able to heat up the car on AC power before you leave. With some API hacking I even had the thing hooked up to Google Home so I could voice activate these commands.

However, 2G is pretty dated technology now, and Rogers (the remaining operator of 2G on which Nissan had all the vehicles registered with on some prior agreement) is finally pulling the plug after extending it for a year. This has happened a while back in the US and Nissan even offered to pay for most of the upgrade, costing the consumer only $199 USD. However, in Canada they did not offer this option and a few years back when people started thinking about this, various folks were getting answers ranging from "its not possible" to a whopping $2000 or so from the dealers. Since then, the active recall on most 1st gen LEAFs was to just disable the 2G before the service ends.

For posterity, I took a snapshot on Dec 31 2020, which is probably one of the last time the car "talks" back to the server/app:

While I considered building my own OVMS setup complete with an always-on lithium pack and GPS module for location logging, in the end I decided to hold off for now as finishing off this PhD while raising two kids after packing up our lives on the other side of the continent means there are probably more pressing matters to attend to ;). Also, since we're back on the milder West Coast now, the need to pre-heat/cool the car is a lot less, considering it is parked in the underground parkade most of the time.

One thing that I will probably miss more than the other features of Nissan Connect/CarWings, is the extensive data that I was logging prior to the shutdown. While I got lazy after a certain amount of time (and having moved to where the JuiceBox wasn't logging charging data any more), the nearly two years of monthly charging and driving yielded some interesting overall results. The most interesting one is probably this one, that shows that there is an optimal ambient temperature for driving efficiency. Each dot is the average of an entire month of driving, plotted against the average temperature:

Based on this, the efficiency peaks at somewhere between 10 and 20 C, and the best explanation beyond extreme temperature situations that limit battery performance is that there is very little use of AC/heat! Since most of our driving is in the city and we spend quite a lot of time sitting in traffic, the energy used to not move the car becomes quite significant, especially in winter.

Coupled with this, here is the power grid to battery conversion efficiency:

Note that this was nearly all at L2, which should have as high as low 90%'s conversion efficiency from wall input to battery output. In the winter, even though the actual L2 charging rate remains similar, we spend a lot more time topping up the pack (which means having to trickle charge/balance the pack as it approaches 100%, and that wastes more energy than charging at full speed at lower levels). There's probably some cold weather dependent behaviour on the battery itself too, but I would guess at this point most of it is because we need to top up to 100% a lot more often in the winter. The final graph, showing how many days between charges, kinda corroborates this:

Here we see that in general, the colder it is, the fewer days there are per charge. In the worst months we're basically charging every single day. Of course this doesn't take into account variability of driving habits, but when you take the same commute every day over a period of 2 years, the data tends to be relatively consistent even if you take the odd weekend trip here and there...

When we first realized that there was no route for Nissan to (reasonably) provide this TCU upgrade, I was definitely a bit disappointed since the car logged all this information in the background automatically. Having the exact energy consumption over distance driven for every trip was pretty neat from a data perspective (privacy advocates should probably take note of this however). But in the end, I guess I can be glad that I was able to get this data while it worked, and I'm sure if (when) we get the next vehicle, the kind of connectivity options will be even better. The Nissan API was extremely slow and didn't work from time to time, but overall, it served us well for the couple of years we had it.