What are the technical barriers to large battery-electric trucks?

[Chris TX]

As much as it pains me to say it, Wal-Mart has the right idea to focus on the rig's efficiencies. If Wal-Mart owns the tractors, trailers, and all of the stopping points (distro warehouses and stores), this could be an end-to-end solution.

1. Fully electrify these trucks with an option for a diesel genset
2. Have Superchargers at the stores to charge while the truck is unloading
3. Have Superchargers at the distro sites to roll over to charge in between loads.

That infrastructure would be groundbreaking and would start to revolutionize the trucking industry.

 

[cantdecide]

For the semis... Weight is important. Drivers' time is cheaper than gas. Put battery swap in every 50 miles on the big highways... Use a standard p85 setup with a small diesel setup that the driver can control. Stop for 2 minutes each hour and save up to $30 for someone who is paid not much. Stick to the big corridors and you are 95% on battery. Predict when you will be going too far for the battery and turn on the diesel early... And get a little help going uphill also.

 

[deonb]

Battery swapping would also be an easy task - most of those places have forklift trucks.

One other thing to consider: You don't have to swap the batteries. You can swap the semi.

So let's say you're a trucking company, and put a set of stops up every 200 miles down the cost (5 of them). So a trucker comes in, and while he goes to the bathroom, an operator uncouple his trailer, and couple in a new semi. And off the driver goes to the next stop. And you then recharge that semi - let's say 6 hours using a H-H-H-PWC.

Sure, you'll need 3 times as many semi's as your competitors, but because of that they'll last 3 times as long. And you'll have a quarter of the fuel costs of your competitors.

There might be math in there somewhere that works out...

 

[ElSupreme]

Also, it wouldn't be 6,000 extra pounds - Class 8 trucks have 2600-3200 pound engines (PACCAR MX-13, Cummins ISX15) and massive thousand pound transmissions and over a thousand pounds of diesel fuel. OTR trucks have to carry an APU now (350-500 pounds,) and then there's turbos and exhaust stacks and huge radiators and so forth.
Walter

Yeah but a 400kWh battery is going to weigh 8000 lbs by itself. And that isn't going to get them anywhere near 500 miles. Add in a pretty beefy motor, and beefy differential. And you are looking at 4k+ extra pounds over a traditional semi cab.

 

[jerry33]

Yeah but a 400kWh battery is going to weigh 8000 lbs by itself. And that isn't going to get them anywhere near 500 miles. Add in a pretty beefy motor, and beefy differential. And you are looking at 4k+ extra pounds over a traditional semi cab.

Right. It's the weight. Every pound that the vehicle weighs is a pound that doesn't bring in income. Now there are some types of cargo that max out in volume but they are in the minority. Until batteries get to the point where there is no weight penalty, it will be a very hard sell for long haul truckers.

 

[Saghost]

Yeah but a 400kWh battery is going to weigh 8000 lbs by itself. And that isn't going to get them anywhere near 500 miles. Add in a pretty beefy motor, and beefy differential. And you are looking at 4k+ extra pounds over a traditional semi cab.

I can get 425 kWh from 6500 pounds simply by piling 5 Model S packs on top of each other, so I'm thinking that's a worst case. The differential would be the same as on the existing trucks.

From a maximum power, torque, and speed range standpoint, the motor out of a performance model S is sufficient if it is hooked to the existing differential on top of its normal gearing, but I don't know if the cooling would be sufficient for the sustained power output.
Walter

 

[ElSupreme]

I can get 425 kWh from 6500 pounds simply by piling 5 Model S packs on top of each other, so I'm thinking that's a worst case. The differential would be the same as on the existing trucks.

From a maximum power, torque, and speed range standpoint, the motor out of a performance model S is sufficient if it is hooked to the existing differential on top of its normal gearing, but I don't know if the cooling would be sufficient for the sustained power output.
Walter

Your telling me that the differential that is in the Model S can pull 80,000 pounds? I highly doubt that. The cooling and most likely motor size is not even close to being sufficient. You can't drive a car on a track for ~90 seconds without having significant power reduction. And pulling 80,000 pounds even up a slight grade is going to take WAY more power than pushing a Model S around a track.

 

[Saghost]

Your telling me that the differential that is in the Model S can pull 80,000 pounds? I highly doubt that. The cooling and most likely motor size is not even close to being sufficient. You can't drive a car on a track for ~90 seconds without having significant power reduction. And pulling 80,000 pounds even up a slight grade is going to take WAY more power than pushing a Model S around a track.

No. I'm telling you that I would use the differential that's in the existing truck's solid axle, and attach the motor reduction gears to that (presumably with a driveshaft,) giving 30 or 40 to 1 gear reduction on the motor overall.

The peak power of the performance model S is equal to that of many new class 8 trucks. The only part I'm not sure about is the cooling for sustained power. One option (which would add weight/cost) would be to use two standard model S drive motors and a custom gearbox to combine them before the driveshaft.
Walter

 

[Lloyd]

Yeah but a 400kWh battery is going to weigh 8000 lbs by itself. And that isn't going to get them anywhere near 500 miles. Add in a pretty beefy motor, and beefy differential. And you are looking at 4k+ extra pounds over a traditional semi cab.

Right, but you save, not hauling 200 gal of fuel, 1600 lbs, and the motors weigh less. Diesel motor is typically 3,000 lbs to produce 560 HP and ~1500 ft lbs of torque.

 

[ElSupreme]

Right, but you save, not hauling 200 gal of fuel, 1600 lbs, and the motors weigh less. Diesel motor is typically 3,000 lbs to produce 560 HP and ~1500 ft lbs of torque.

Yes but 1600 + 3000 != 8000. Thus my 4000 lbs more comment.

You can look at passenger cars as well. Show me one EV that is lighter than a comparable ICE in weight. There isn't one. EVs weigh more than ICEs right now. That is a HUGE impact on the cost of trucking.

 

[Lloyd]

Yes, but out of an 80,000 lb load that is only 5%

 

[ElSupreme]

Yes, but out of an 80,000 lb load that is only 5%

Still 1 or 2 pallets or ~5-10% of a load at the plant I work at. Which means 5-10% more trucks, 5-10% more paperwork, 5-10% more dock switches, 5-10% more trailers. And they do over 100 trucks a shift.

And ~450kWh is only going to get a semi barely 150 miles. Still a crippled vehicle when you are comparing to a traditional one.

It will happen, but not until batteries get way better, or fuel gets way more expensive.

 

[Lloyd]

Still 1 or 2 pallets or ~5-10% of a load at the plant I work at. Which means 5-10% more trucks, 5-10% more paperwork, 5-10% more dock switches, 5-10% more trailers. And they do over 100 trucks a shift.

And ~450kWh is only going to get a semi barely 150 miles. Still a crippled vehicle when you are comparing to a traditional one.

It will happen, but not until batteries get way better, or fuel gets way more expensive.

I see your point..... Perhaps it would be fitting for those trucks/loads that 'bulk' out before they gross weight out!