A Thought for Electric Vehicle Manufacturers – Introduce a Special Reserve Mode

As some of you know, internal-combustion-engined vehicles behave in a certain way when they run out of fuel. While it is a rare occurrence, it may happen. Most vehicles just stall where they run out of fuel, but others may give you a slight warning if they are running low, which may leave just enough time for you to pull over.

For example, back when I had a motorcycle with a carbureted engine, it had a shut-off valve between the tank and the carburetor, and there was a “reserve” mode on top of the “ON” and "OFF." The latter two are the bare minimum for this kind of valve, and they allow someone to stop the flow of fuel to a carburetor to perform maintenance work without fuel spilling from the gravity-fed tank.

While it was not an industry standard (as far as I know), I learned that many other motorcycles had one. The idea with it was that you did not have a fuel gauge or even a low-fuel-level light, so there had to be a way to provide a bit more range in a pinch.

Once I got the hang of it, I could sense the moment when my 1994 Kawasaki GPZ 500S was about to run out of fuel, and I could just switch it to reserve as I was riding. I would only have to remember to fuel up soon, and that was it.

If I were not riding at high engine speeds, I could sense the moment when fuel was running low and make the switch. It worked the same way on my Honda CBF600.

I have only encountered the situation of running out of fuel in a vehicle in my family's (now) classic Mercedes, but only after presuming it still had a fair amount of fuel in the tank, as the gauge showed ¼, which means a quarter of the tank.

Sadly, the gauge was misled by the fact that the vehicle was parked in a banked spot, which led to an erroneous readout. It has not happened to me since.

In electric vehicles, things work a bit differently. The battery of an EV has a gross capacity and a net capacity. The latter is the one that you get to "use," while the former represents the entire capacity. To prevent damage to the battery and ensure it is more durable, some claim that automakers leave a slight “buffer” on the battery level gauge.

With context out of the way, here are two ideas on the matter. First, automakers should enable a small reserve integrated into each electric vehicle, which would kick in when the remaining range hits zero, but would require the driver to press "OK" or would come with audio and visual notifications. The vehicle would be able to move under its power in the given situation, but it would drive in a limp-home mode, with limited power and limited maximum speed.

It would be better than getting stranded on the side of the road if you are not paying attention to the battery level gauge in an electric vehicle. From personal experience, I can say that most electric vehicles will warn the driver if their energy level is alarmingly low, and there is no chance to ignore it.

The only reason to justify running out of energy in an electric vehicle without being negligent would be if you had planned to drive to a particular EV charging station, and it did not work. Otherwise, you miscalculated the trip, drove too fast, or something in between. A reserve mode would prove handy, right? It would be better than pushing the vehicle if you ask me.

The second idea that came to mind was also a suggestion to vehicle manufacturers – specify in the owner's manual what happens when an electric vehicle's range estimate reaches zero and its battery is also at zero percent.

It would help people be more relaxed if they knew that there was a possibility of driving their car for three miles at city speeds when the battery reaches zero percent. Enabling a reserve mode, as suggested above, would be an alternative – it could probably be programmed and offered as a free update.