How hard would it be to make an electric semi truck

[JRP3]

Loads of mixed packages might average out, but dedicated loads of single products would certainly have different densities, i.e. pillows vs barbells.

 

[dhanson865]

Loads of mixed packages might average out, but dedicated loads of single products would certainly have different densities, i.e. pillows vs barbells.

Yeah I'm thinking about this stupid shipping gang – Consumerist just browse a few of those and look at the pics of boxes that are 90% air. A huge amount of shipments from online shopping are like that.

 

[Red Sage]

Use your imagination. A 3500 lb 5-passenger car manages to carry about 900 lb of cargo (passengers and luggage) about 25 miles on one gallon of gasoline. Vehicle weight to cargo ratio = 3.9 : 1
A 4500 lb Tesla carries the same load the same distance on about 10 kWh of power, using a 1200lb 85 kWh battery. Vehicle weight to cargo ratio = 5 : 1
A loaded truck & trailer weighs about 80,000 lb and carries a 40,000 lb payload 25 miles on about 4 gallons of diesel. Vehicle weight to cargo ratio = 1 : 1
How big would that electric truck's battery have to be to deliver enough power? Bear in mind that the legal weight limit per axle is 12,500 lb, so battery weight has to displace cargo weight (so does fuel in a diesel, but 250 miles worth of diesel weighs just 264 lb. on a vehicle 16 times as heavy as Model S.

I look at it another way... Diesel fuel is slightly more energy dense than gasoline. Or, 40.7 kWh per gallon. If one gallon of diesel will move the vehicle 6 miles, that is equivalent to 6,783 Wh per mile energy consumption. Electric vehicles are far more energy efficient. So it would take less energy to move the same distance in an EV powered truck. If you presume that a diesel system is 38% efficient (they aren't) and the EV were 90% efficient... That means of the 6,783 Wh expended per mile for the diesel, only 2,577 Wh were used for actual motive force. So, an EV would need to have 2,864 Wh of available energy to travel one mile with the same load. Thus, in order to get a range of 600 miles, you need a bit over 1,700 kWh of battery storage. In practice, you'd probably end up with four separate 400 kWh battery packs. Yes, they would be much heavier than the diesel fuel, and yes, their weight isn't going to drop 99.9% as electrons are 'burned'... So you always have to carry the 'extra' weight around with you, but that is no big deal. How much would they weigh? Idunno. But I suspect it would be nowhere near the 12,500 lbs per axle limit.

 

[Red Sage]

Tesla semis mentioned in master plan 2, BOOM!

Here, I'll help with that...

 

[Red Sage]

I think the hardest part will be delivering enough electricity to truck stops to charge 30-50 trucks at once at 500kW each.

I think this is where the notion of battery swap comes to fruition. If someone really does need to 'hit the road' immediately, that would do the trick. Supercharging could still add 50% in half an hour, and in the big wide, open spaces along US roads, solar power with battery backup would be superb.

 

[Red Sage]

Not Perpetual motion because only 1 motor charging/supplementing 2 motors using, eg your using more than you can generate thus needing to recharge at some point.

OK. We'll call it a 'perpetual stopping machine' instead. Because what you describe amounts to driving with the front brakes on all the time.

 

[Red Sage]

A 600kW unit should juice the T300 up to 80% in roughly 20 minutes. Introduced in strategic alliance with [gas station company] for deployment along all major transportation routes.

Or even exclusively available at Tesla Depot locations that are EV Specific...?

 

[K5ING]

I think this is where the notion of battery swap comes to fruition. If someone really does need to 'hit the road' immediately, that would do the trick. Supercharging could still add 50% in half an hour, and in the big wide, open spaces along US roads, solar power with battery backup would be superb.

I can also see a case for Tesla built tractors and flatbed trailers. Fill the flatbed with batteries under the floor and use containerized cargo. When it comes time for a swap, the driver (if there is one!) would just pull in under an overhead crane which would lift the cargo and place it on the fully charged flatbed next to it. The driver switches the tractor unit to the new flatbed and goes on his way while the discharged flatbed trailer charges and awaits new cargo. As I said, it would require containerized cargo but it could also carry bulky items that flatbeds traditionally carry, and would eliminate the need for rapid charging. Of course, the flatbed trailer can also have motors to help, especially in bad weather. The tractor unit could have enough batteries to deadhead, say, 100 miles also if needed.

 

[Snow Drift]

So will Tesla buy Nikola Motor or hire their people or just allow competition to flourish?

 

[Red Sage]

So will Tesla buy Nikola Motor or hire their people or just allow competition to flourish?

Tesla Motors is a fan of competition. Elon Musk that healthy competition is essential to growth. He stated so long ago, and reiterated many times since. Especially after opening Tesla's patents.

 

[ZAKEEUS]

My random thoughts on this thread.
There is no need for rapid charging if you can get good enough range, there is plenty of time to charge while on break. Truckers are only allowed to drive for 11 hours a day. They are only allowed to work for 14 hours a day before their mandatory 10 hour break. You could add in a rapid charger for the required 30 minute break which has to be taken before reaching 8 hours on duty. Newer trucks are getting 7mpg fully loaded and about 10 with an empty trailer. I did 500 miles yesterday and finished at 9.3 mpg. The legal weight limit per axel is not 12,500 lbs. The steering axel limit is 12,000lbs. Drive and trailer tandems are 34,000 each. If we get to a point where most trucks are able to drive themselves on the highway, maybe the FMCSA would back off the requirement for drivers to take a break between 1-5am. That would allow more truck drivers to drive Safely at night while avoiding rush hours.

 

[JRP3]

So using 9.3 mpg and 500 miles that's 54 gallons of diesel, using 40kWh of energy per gallon that's 2160kWh, x 35% efficiency = 756 kWh of energy actually put into motion. We'll add 10% to that for buffer and EV drive losses which gives a 831 kWh pack. 756 kWh available would mean 500 miles at 1512 Wh/mi.

 

[ZAKEEUS]

So using 9.3 mpg and 500 miles that's 54 gallons of diesel, using 40kWh of energy per gallon that's 2160kWh, x 35% efficiency = 756 kWh of energy actually put into motion. We'll add 10% to that for buffer and EV drive losses which gives a 831 kWh pack. 756 kWh available would mean 500 miles at 1512 Wh/mi.

One more thing to consider is fuel used at idle while on break. The average is 1-1.5 gallons per hour. This is probably 9 hours out of the 10 hour break. An electric truck wouldn't need Diesel Exhaust Fluid, which is currently more expensive per gallon than the diesel itself. 1 gallon per 300 or so miles times the life of a truck 1.5-2 million miles.

 

[S'toon]

Mercedes-Benz To Compete With Tesla In Electric Semi Truck Segment

 

[Ibrido]

Battery swapping makes even less sense for large vehicles then it does for passenger vehicles...

Besides, it won't be needed at all as large batteries charge super fast. My feeling is these will be coupled with a new type of Supercharger intended for commercial vehicles - the SuperDupercharger

A 600kW unit should juice the T300 up to 80% in roughly 20 minutes. Introduced in strategic alliance with [gas station company] for deployment along all major transportation routes.

Super fast charge comes at a price .. Life of battery. The more you use quick charging the more quickly it will come near to replacement.

 

[JRP3]

In general yes, but it really depends on the C rating of each particular chemistry and physical cell construction characteristics. Supercharging seems to have little to no negative effects on Tesla packs.

 

[WarpedOne]

The more you use quick charging the more quickly it will come near to replacement.

Such is the layman wisdom.
Experimental data does not uphold it.

 

[Red Sage]

Such is the layman wisdom.
Experimental data does not uphold it.

True enough... But there is the phrase 'Super fast charge' used at the beginning of the post. Something tells me that charging two, four, or eight times as quickly as Superchargers currently operate will develop... issues, and stuff. When it comes to longevity and durability of battery cells.

 

[ItsNotAboutTheMoney]

So using 9.3 mpg and 500 miles that's 54 gallons of diesel, using 40kWh of energy per gallon that's 2160kWh, x 35% efficiency = 756 kWh of energy actually put into motion. We'll add 10% to that for buffer and EV drive losses which gives a 831 kWh pack. 756 kWh available would mean 500 miles at 1512 Wh/mi.

So, let's say 1.5kWh/mi, driving at 70mph, for 11 hours of 14.
That's 770 miles.
Then you need 1.5kWh/mi x 770mi = 1164.24 kWh of charge per day.
Simplified assumptions:
start with 100% charge, deplete to 0%, charge to 100%.
1 hour to charge to 100%. (1C).
So:
1 + 3 x 1 = 4 full charges requiring 1164.24 kWh implies 291.06kWh/charge.
If you want 80% usable then it'd require 363.825kWh of battery.
So, about 4 x 90kWh packs. Make it 5 x 90kWh packs and get more breathing room.

OK, so how much does a 90kWh pack weigh?
Well, let's use an old 85kWh number of 1323lb and scale:
5 x 1323 * 90/85 ~= 7004lb.

That's actually not totally insane.
But that 1.5kWh/mi...
Let's say that due to the shift away from petroleum, diesel remains pretty cheap and the underlying diesel price is $2/gal. Then at 9mpg the cost is $0.222/mi.
Electricity: at 1.5kWh/mi, then break-even price _even ignoring the charging losses_ would be $0.147/kWh.

 

[JRP3]

So, let's say 1.5kWh/mi, driving at 70mph, for 11 hours of 14.

I imagine average speed would be less than that.