A recent blog by Patrick Mannion on EDN has floated the suggestion that "In all probability current electric vehicles will have an actual expected range of 10% (or less) of the advertised life."  This (and those of you who think me an EV-pessimist may be surprised to hear me say this) is somewhat over stating the case!

Take a Nissan Leaf with a 24kWh battery pack, and a whole bunch of worst-case assumptions.

Let’s assume that 80% of that is allowed to be used, and that after 5-10 years of regular fast-charging, 70% of that capacity remains.  That gets us down to a usable 13.4kWh.

The worst-case scenario consumption scenario for an EV is arguably constant flat-out high speed driving.  This consumes a lot of energy, with no opportunity for brake-energy recuperation.  The limited top speed for a Leaf is 90mph.  I reckon to push a Leaf through the air at 90mph takes around 33kW of power.  Let's add on 3kW worst-case additional electrical loads (lights, heater, stereo at max etc.)  Total power consumption is now 36kW.  This means that 13.4kWh will last around 22 minutes at 90mph.  That will take you around 33 miles.  

So yes – a max-speed blast in an aging Leaf with high electrical loads could see you running out of juice in around 20 minutes, having covered a bit more than 30 miles.  However, this is still around 30% of the advertised range – NOT the 10% postulated in the EDN blog!

This is why EV top speeds are limited.  The Leaf has an 80kW motor.  Were it allowed to run flat-out continuously, at a consumption of 83kW (with our 3kW electrical loads), the “aged” battery would only last 13.4/83*60 = 10 minutes.  I reckon 80kW would push a Leaf to around 126mph flat out, giving it a range-at-top-speed of only 20 miles.

But that’s still ~20% of advertised range, not 10%.

As someone who spends a reasonable amount of time aboard aircraft, I have a certain interest in air safety. I recently came across an article on MSNBC titled "Are airline pilots forgetting how to fly?" This essentially argues that some recent fatal crashes have been caused by pilots being unfamiliar with how to operate the airplane when the automatic systems fail.

The automotive industry is clearly well behind aerospace in the levels of automation offered.  The article states that it is commonplace for the crew to only manually fly the aircraft for 90 seconds at each of take-off and landing.  However, with the increasing level of ADAS (Advanced Driver Assistance Systems) and other support, do we risk de-skilling drivers?

What will the driver who has relied on their automatic parking system do when it fails?  What will the driver used to autonomous cruise control do when driving a rental car without it?  I know from my own experience the momentary confusion that can often arise when switching to and from vehicles with manual and automatic transmission.

The industry is progressing upon generally sensible lines.  For example, the Volvo City Safety system, which can apply emergency braking effort automatically, offers no audio/visual warning to the driver.  This is deliberate, the thinking being that if it did, drivers may begin to rely on the system to keep an eye out for them.  The system intervention is deliberately late and harsh, so that it is truly an emergency aid only.

However, we regularly see examples of people taking dangerous and unsuitable roads because their sat-nav told them to.  Some seem to have already delegated navigation responsibilities to a machine, and will obey it blindly.

Safety and support system designers will need to keep a close eye on ensuring that they do not unintentionally de-skill drivers and leave them in situations that they no longer have the talents to deal with.