The Slow Death of the Internal Combustion Engine

[redpoint5]

Even more interesting to me is if a loaded semi will be able to maintain higher speeds when climbing a grade. Potentially more time savings there.

The main point isn't time savings though, but to lower the operating costs associated with fuel and maintenance. Time is a bonus.

[JSH]

Originally Posted by redpoint5

Even more interesting to me is if a loaded semi will be able to maintain higher speeds when climbing a grade. Potentially more time savings there.

The main point isn't time savings though, but to lower the operating costs associated with fuel and maintenance. Time is a bonus.

It is a trade off between time and money. Class 8 trucks vary wildly in engine specs anywhere from 250 to 600 hp and 1000 - 2000 lb-ft of torque. Plenty of trucks can maintain speed on grades but doing so burns a huge amount of fuel. (Just like blasting up a grade at 80 mph depletes a battery very quickly)

The problem with Tesla's claims is that they don't tell us the diesel truck they are using for comparison.

[Xist]

How much time can semi drivers (and potentially small vehicles stuck behind them) lose due to hills on common routes?

I found this from a seeming veteran truck driver: "I pull a lot of loads that put me in the 75,000-79,999 range, and I also do a lot of driving in the Rockies. Sometimes I have trouble keeping it above 25 on the uphills." https://www.truckingtruth.com/trucke...ng-40k-lb-load

I know that semis on I40 drive 75 MPH, but if we say that 65 MPH is closer to the average speed limit [for trucks] in the U.S. [any of our trucker friends reading this?]; if a trucker spent 10% of their drive going half the speed limit, that makes the trip 5% longer. Instead of saving 1.1% in the scenario I described before, this would save 5%.

My other concern was that accelerating harder should use more energy, but as long as you can climb the hill, you should be able to use regenerative braking.

I am not sure how important the argument about using electric trucks as trucks shortening their range.

How many people use trucks as trucks?

[redpoint5]

There's essentially no efficiency penalty for going up a grade at a faster speed (higher power output) with an EV except for the aero penalty of the higher speed. That equally applies to flat travel though, so there's no reason to slow down for a hill with an EV if it's capable of maintaining speed.

Gasoline vehicles tend to be most efficient at about 80% torque, and 50% of rated horsepower. I'm not sure about the BSFC for diesels, but they can probably be very efficient to the upper portion of their power rating.

The EV trucks would indeed recapture much of the energy spent climbing the grade.

EV drivers report little difference in overall efficiency with regard to climbing grades as long as the destination elevation is approximately the same as the departing location. Efficiency plummets while climbing, and is recovered on the way back down.

As an aside, many truckers are paid per mile. That means when they are going slower than the speed limit, they are getting paid less. Hills can be seen as a reduction in pay... unless you can maintain speed.

Semis in Oregon average about 60 MPH with a speed limit of 55.

[JSH]

Originally Posted by redpoint5

As an aside, many truckers are paid per mile. That means when they are going slower than the speed limit, they are getting paid less. Hills can be seen as a reduction in pay... unless you can maintain speed.

True but there are also fuel economy bonuses for hitting fuel economy targets and if you consistently burn too much fuel you can be fired. (Previously company had their own truck fleet and required a minimum of 6 mpg)

Fuel bonus can be up to 8 cents per mile which is a big boost to the typical 30-40 cents per mile rate.

Driver pay is also a lot more complicated than it seem. There are drivers that get a set hourly wage. Then there are the company drivers that get paid by the mile. Then the guys that lease the truck at a weekly fee from their company and pay their own expenses. Finally the owner / operator that pays everything out of pocket.

[redpoint5]

Well EV trucks solve both the problem of low speed, and the problem of poor efficiency. The main consideration then becomes turning around the truck as quickly as possible.

I wish I knew something about the trucking industry because I think EVs could be a gamechanger for short-medium hauling. Would be great to snatch up those contracts/routes that would most easily accommodate EV delivery.

[JSH]

Originally Posted by redpoint5

Well EV trucks solve both the problem of low speed, and the problem of poor efficiency. The main consideration then becomes turning around the truck as quickly as possible.

I wish I knew something about the trucking industry because I think EVs could be a gamechanger for short-medium hauling. Would be great to snatch up those contracts/routes that would most easily accommodate EV delivery.

For long haul the next step is hybrids. You get the electric boost accelerating and climbing hills plus the advantage of regeneration braking and going down hills.

For Class 8 EV trucks the industry is focused on drayage (port to depot) and within ports. Those types of routes can easily be accomplished with a 200 mile range and the truck can charge at the depot. They are also generally found in cities where pollution is a big concern.

For light and medium duty EVs the focus is on local delivery and trash collection. Those routes are generally 100 miles or less per day. Again, the truck can return to the depot to charge.

[redpoint5]

No reason why we're still sending diesel garbage trucks out with worn out squealing brakes to wake the neighborhood at 6am.

[Frank Lee]

School busses should be EV. They put on a zillion miles daily, often in an ev friendly radius.

[JSH]

Originally Posted by Frank Lee

School busses should be EV. They put on a zillion miles daily, often in an ev friendly radius.

Working on it: https://newpowerprogress.com/thomas-...ic-school-bus/

The problem is school buses actually don't drive that many miles in a day so the break even is poor. The average is 62 miles per day.