Hacker News Reader

Comment by smarx007 | Hacker News Reader

> motorway speeds

Do you mean 110..130 km/h EU speeds or 150+ km/h Autobahn speeds?

Driving 130 km/h can knock ~30% off your range compared to driving 90 km/h according to various sources[1]. Add cold on top of that and losing 50% over advertised range seems reasonable.

If you want to optimize for range you should apparently aim for holding a constant 50-55 km/h.

[1] https://teslike.com/

https://cleantechnica.com/2018/07/15/tesla-range-plotted-rel...

50% loss in the cold is pretty darn high. You can mostly eliminate the cold range loss by:

- preconditioning the battery & cabin while the car is parked and plugged in

- using one of the newer models with a heat pump

- turn the cabin heat down and the seat heating up

The first point is the most important. We often have little range loss on our way to the destination but significant on the trip home because we couldn't plug in at our destination and the car got cold.

It is indeed unrealistically high, and I say this as a Canadian driving my Volt in a Canadian winter. I only see about 30% reduction even in -20C.

That said, the Volt will warm the system with the ICE if it gets below -10C. But I've heard similar numbers from pure-BEV owners.

> If you want to optimize for range you should apparently aim for holding a constant 50-55 km/h.

I think rather 80-90 km/h, at least for Nissan Leaf, as well as from the table you linked (55 mph ~~ 89 km/h)

I own a Nissan Leaf and can confirm 90km/h is about the sweet spot for trip duration. Above it, you're draining battery faster than you can recharge it. Below it is unsafe on motorways. I usually set it at 104km/h, which makes the estimated range pretty much exactly match reality.

However, for newer EVs the sweet spot will be at higher speeds, because those cars are able to recharge at much higher speed (at least 2 times faster).

from the table you linked (55 mph ~~ 89 km/h)

The table doesn't show any data below 55 mph. This site: https://cleantechnica.com/2018/07/15/tesla-range-plotted-rel... has a graph that plots range vs speed all the way to 0 (for the Model S) and it shows the 'optimal' speed to be around 35 mph.

My bad, didn't check the second link, thank you. The data looks too smooth. Is there raw data somewhere? Or analysis without too much regression applied?

And draft behind a truck! I know a guy who’s skoda has something silly like 3.6l average consumption over 250km.

For your "average car", driving at 160 kph/100 mph requires 3x the energy as 110 kph/70 mph (due to aerodynamic drag), while only increasing velocity by 1.45x. Simply put, you're requiring 2x the energy per unit distance, which pretty neatly lines up with losing half the manufacturer rated range.

You can’t drive in a German motorway at 110kph. You’d be in the truck lane at 80kph for your whole trip, having to over take every single truck, of which there are many. So 130kph+ is the minimum unless you are towing.

I was doing 160km on (most of) the Autobahn from basically the top of Germany to the bottom.

Sounds incredibly dangerous. You mentioned you had most of the voyage at -5C. Were you worried about road ice?

Lived in Germany several years and it was not unusual to get wild game cross the street at the worst times. Most Authobahn have protections against, but some parts are badly maintained and I have seen some crossings...

"Wild Boar Crash Test Highlights Growing Accident Risk" https://www.spiegel.de/international/zeitgeist/road-carnage-...

In 2010 for example... "...A total of 27 people died and 3,000 were injured in a quarter of a million collisions with wild animals on German roads in 2009, not to mention the hundreds of thousands of animals that perished in the process..."

I was not worried. The Autobahn is one of the safest road networks in the world because of how well it's maintained and how well drivers follow the rules. Of course one should always stay vigilant. I've done the trip many times before and know the potential hazard zones. Wild animals jumping out at high speed is a risk almost anywhere in the world. According to your stats, that risk is exceedingly low compared with the actual miles driven each year.

Reply on news.ycombinator.com