The Tortoise and the Hare

My brother has been living in Singapore for over a year now, but came over to Oxford for a conference at the university last week. As I haven’t seen him since early last year, the weekend seemed like the perfect opportunity to meet and have a catch up.

Oxford is around 200 miles from my house in Skipton, so outside of the range of even the 30kWh LEAF that I am now driving. However, it is perhaps indicative of my confidence in the range of the LEAF, and the multitude of charging options available these days, that I was more worried about how to keep my two sons occupied for the 4 hour journey, than where and when I ought to be charging my LEAF en-route.

There are chargers at all of the motorway service stations I would be passing, so I just decided that I’d aim to stop when I got down to around 15-20% charge. I had been pre-warned that parking in the middle of Oxford was akin to Airport short-stay parking prices, and therefore I was going to park at the Park&Ride site to the north of Oxford, at the Pear Tree interchange. A quick check of Zap-Map showed that there was a 7kW charge point on the Polar network at the P&R site (a remnant from when Mini was trialling an electric mini concept in the area several years ago), as well as an Ecotricity Rapid (50kW) charger at the service area, a matter of a couple of hundred yards away.

So we set off on Saturday morning, just after 9am, with 100% charge in the battery (overnight, from my home charger). The first part of the journey is over some very steep hills (1200ft above sea level), which makes it difficult to drive in an “eco” way. However, what goes up must come down, and therefore we were able to gain some range when driving down the other side. From Colne, we took the M65 towards Preston, then the A56 to the M66, then around Manchester on the M60 to the M62, then M6 south to M42, then M40 down to Oxford.

This brings me to the Tortoise and the Hare. Aerodynamic drag increases with the square of speed. Therefore, if you drive at or above 70mph, despite the LEAF having a drag coefficient of just 0.29, the act of overcoming wind resistance means that you use an exponentially greater amount of energy to go just marginally quicker. So if you drive at a slightly slower speed, you will use less energy, and therefore will be able to travel further before stopping for electricity.

According to Aesop’s fable – the tortoise, tired of the hare’s boastful behaviour, challenges the hare to a race. The hare soon leaves the tortoise behind and, confident of winning, takes a nap midway through the race. When the hare awakes however, he finds that his competitor, crawling slowly but steadily, has arrived before him.

I therefore adopted the “Tortoise” method – staying in the left lane, following the trucks and coaches at around 60mph. This has a two-fold effect, as not only are you keeping your speed down, but the trucks also push the air out of the way, so your car has less work to do. This worked very effectively, as despite the climate control and heating being on (it was just 3-6°C outside), we managed to reach Stafford services after 98.9 miles, with 15% (20 miles) still available.

As it was almost 12 o’clock (ok, 11:28), and my boys were hungry, we went inside for a McDonald’s, and left the LEAF on charge. By the time we’d finished lunch (12:14), the LEAF was charged up to 94%, with 130 miles showing on the “Guess-o-Meter” (Range estimate).

 

According to the sat-nav, it would be just over 100 miles to the Pear Tree Park & Ride, so I felt confident that I’d be able to make it straight there without any further stops (although I would pass several motorway services, and rapid chargers between Stafford and Oxford, so would be able to stop earlier if needed).

I set off along the M6, and settled behind a suitable truck. We carried on at a steady pace all the way down to the A34 turn off on the M40. We arrived at our destination (14:19), having covered 101.2 miles, and using just 74% of the battery. We had 20% left on the battery, which due to the way that we had been driving, would have given us another 30 miles of range if needed.

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This just goes to show that if you’re willing to sacrifice a few mph, you will reap the benefits in terms of range.

Luckily, the sole chargepoint in the park & ride car park was unoccupied, so we connected up the Type 2 to Type 1 cable, activated the point with my Polar network card, and hopped on the Hybrid double-decker into town. It cost £2 for parking at the site, and a further £2.60 for myself and two boys’ bus tickets.

We met up with my brother, and went for a very enjoyable afternoon looking around the Oxford University Museum of Natural History. After a spot of dinner, we went back to the car (18:55), now fully charged, and very optimistically showing 150 miles on the range meter.

We drove to our hotel (Premier Inn Oxford, near the Mini factory), and retired for the evening. Well, that was the idea… but my two boys were still bouncing around well after 10pm!

TO BE CONTINUED…

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