The writing has been on the wall for a while now: Electric cars are here to stay, the death knell is ringing for fossil fuel.
That’s all very black & white though, and the reality is perhaps a little different. Certainly, electricity is the motive force of the future, and for the moment, developments are happening so fast that even oil giants like BP are investing heavily in the infrastructure. But can BEVs really cope with everything that internal combustion can?
At the moment, not really.
That isn’t to say that they aren’t a viable alternative right now, just that any owner of a Battery Electric Vehicle needs to get used to that twinge in the pit of their stomach called ‘Range Anxiety’.
Read any write-up, report or owner’s perspective about their BEV and they all mention the same thing – fantastic in every way aside from the range anxiety, which they’ve all suffered from at some point.
Typically, ‘optimum’ ranges can be anywhere between 130 miles – 290 miles depending on the vehicle, but just as manufacturers use their know-how to ‘increase’ the mpg figures for a regular car, so do electric vehicle manufacturers.
One example of this is temperature. Although each manufacturer does carry out extreme weather testing, the published figures are, of course, taken from optimum conditions – battery cells like to be comfortable, around 21 degrees Celsius, start deviating from that temperature, and things start looking different.
The American Automobile Association have recently compared the effect that temperature can have on the optimum range, and staggeringly, it could be as much as 41% to the deficit in cold weather. That doesn’t mean the reverse is true either; warm things up above the optimum, and you’ll still see a decrease in battery reserve, although not as acute.
For the record, we aren’t talking extremes of weather unlikely to be found in the UK – approximately 6 degrees below zero, or 35 degrees above.
Extreme weather effects
The decrease in range is down to a number of elements, partly physics, partly comfort.
Timothy Grewe, chief engineer at the General Motors Electric Propulsion Laboratory explains: “When the weather gets cold, the battery components develop increased resistance that limits how much power they can hold, as well as how fast a battery pack can be charged or discharged”.
That loss of efficiency equates to around 12% without the heater running, but staying warm could add a further 28% loss in range; testers noticed an overall loss of 41% on some models, including the heating system for the battery (which is separate from the cabin heater).
While extreme warmth also loses range, it’s nothing like as much – around 4% without the air-conditioning running, and 17% with.
While few manufacturers have officially commented on AAA’s findings, a spokesperson for Tesla commented: “Based on the real-world data from our own fleet, which includes millions of long trips taken by real Model S customers, we know with certainty that even when using heating and air-conditioning, the average Model S customer doesn’t experience anywhere near that decrease in range at -6 degrees, and the decrease in range at 35 degrees is roughly 1%”.
While we’re used to seeing improvements in the technology, batteries and range, these losses may be difficult to engineer out. An internal combustion engined car has lots of spare heat energy, so diverting some of that to the cabin is relatively straightforward, but an electric car only has the capacity to generate heat by using the onboard electricity.
It’s a similar story for the battery heating system.
It would seem as though the best advice if you have an electric vehicle is to try and pre-condition the car while it’s still plugged in – either heating it up or cooling it down, most of the BEVs allow for this, along with storing it in the garage or at least ‘out of the wind’ where possible.
There is no doubt that electric vehicles are taking big steps toward being a genuine, viable alternative to their internal combustion counterparts, but that’s at a price, both in terms of financial and practicality. There are still a number of issues that need ironing out before they truly beat fossil-fuel in a fair fight, but is that so surprising seeing that the car as we know it has been under development for well over a century?
No doubt that someone will point out that electric vehicles were also developed over 100-years ago, but they were never mainstream, or that both petrol & diesel also lose efficiency when temperatures plummet, but the difference here is that it’s an easy job to refuel, that takes 5 minutes.
Would you own an electric vehicle? Is it something that you want, but practicality or financial reasons outweigh the decision? Let us know in the comments.