EV Range Variables



Range meter animatedRemember, back in the day, when the starter motor in your old ICE vehicle took a bit longer to turn over in the Winter? Or on a cold morning, when you were running late, the starter battery died completely? Or your mobile phone or camera battery went flat too quickly on that snow trip?

Batteries don’t like the cold – the chemical reaction in the cells of a battery is less efficient in cold weather. Battery charge longevity decreases in cold weather. Batteries love 25ºC, not so much 5ºC! And the battery in your EV is no different.

Temperature isn’t the only factor that affects a battery’s state of charge – and consequently the perceived driving range of your EV. Factors that impact battery energy consumption, and in turn driving range, include the speed at which the car is travelling, the use of the heater and air conditioner, how hard the car accelerates when moving off from start, the use of cruise control, if you are driving uphill or ‘coasting’ downhill, how much deceleration regeneration is available, etc, etc. All these things affect how much stored battery energy is consumed per kilometre.

But even more confusing is the vehicle’s electronic ‘fuel gauge’ that tries to estimate the remaining range of the vehicle, in kilometres, based on the interaction of those many mechanical and electronic variables.

Winter vs summer range

This gauge is often referred to as the Guess-o-Meter, or GoM!

In Spring, driving around town at 50 kmh, with Eco mode selected, and little use of climate control, your EV may have an estimated range of over 300 km with a full charge (depending on battery size). The same car, driven on the highway at 100 kmh using cruise control in Winter may see that estimate reduced to under 250 km for the same State of Charge (SoC).

And once the GoM gets it in its head that this is the vehicle’s ‘normal’ range, it may be difficult to recalibrate.

Don’t despair – that’s just the nature of the beast. And it effects all EV’s regardless of price. The battery capacity hasn’t necessarily changed – just the number produced by the electronics interpreting the variables.

When it comes to battery temperature, many EV’s include a system to warm/cool the battery to maintain an optimum operating environment. But of course, these systems also consume stored battery energy.

Most EV’s include software that will display the estimated driving range based on the previous use of the car. If you regularly drive on the highway, travelling at 100 kmh, the GoM may assume that this is ‘normal’ usage, and predict the estimated range accordingly, even if you are only planning on a day driving around town at relatively low speeds. This ‘range guess’ is ultimately based on an estimation of your rate of energy consumption, measured in kWh/100 km…

Current journey gauge animation

On a day-today level, this level of energy consumption is informed by a number of factors, including the use of air-con and heater settings, performance setting (Eco, Sports, etc), regenerative braking settings, and how heavy your right foot is when pressing the accelerator.


Can you change the range estimate to reflect your current driving conditions?

Maybe.

While you can’t change the outside temperature, you may be able to reset the vehicle’s memory of your previous driving performance, so it is able to recalibrate range estimates based on more recent usage patterns.

But this is only a ‘maybe’, and is likely to vary from brand to brand, software versions, etc.

The only way to find out is to give it a try….

Look for the RESET option on your Accumulated Journey consumption dashboard (rather than your Current Journey display)…..

Reset button

After resetting and then driving for a few hundred kilometres, your GoM’s calculations may be recalibrated, based on this more recent driving experience. This may (or may not) help your system to recalibrate range estimates!

Either way, your battery’s stored energy capacity stays the same – it is only the vehicle’s interpretation of the impact on the above-mentioned variables that may be altered. A more accurate measure may be to keep a record of the actual distance travelled (from your odometer) and compare that to the GoM’s calculations.

It is also worth comparing your EV’s range estimates in Winter and Summer to give an indication of the effect of temperate on your car’s range between recharges.



More reading…