3 ms·

I thought this would be similar to the diesel-electric term with respect to trains. Which is also something I’m shocked isn’t (hasn’t?) been tried with semis. G

I thought this would be similar to the diesel-electric term with respect to trains. Which is also something I’m shocked isn’t (hasn’t?) been tried with semis. Get rid of the 18 speed transmissions, have a “max efficiency” mode for regular use, and a “max power” mode for hill climbing.

starbase 3y ago
agreed. diesel-electric powertrain has a specific meaning, and this ain't it. this is a diesel hybrid
- Turskarama 3y ago
  I'm pretty sure it IS actually diesel electric, the engine is only used as a generator with no direct connection to the wheels. It's a full time battery-electric drive with a range extender.
theossuary 3y ago
Yeah I did some research on this a while ago because I had the same thought, diesel/electric drive-train seems like a no-brainer for trucks, and maybe even other vehicles. Basically a generator in an electric drive-train, with the possibility of introducing batteries too. Sadly the main drawback seems to be cost; as is evident in the pricing of the startup's product. More than that, until gasoline vehicle externalities are properly priced in, the cost of any alternative will be exorbitant in comparison. There have been some concept vehicles, and larger commercial vehicles; but they never caught on. It seems like electric will win before diesel/electric has a real chance. I always thought it'd make the most sense on motor homes and the like, where people tend to bring a small generator for electric appliances anyway. https://wikicars.org/en/Diesel-Electric_Hybrid https://wikicars.org/en/Diesel-Electric_Hybrid
- pixl97 3y ago
  Electric cannot win in semi applications for the foreseeable future. We'd need many more terawatts of power in the to supply their needs.
vvanders 3y ago
Yeah, I think there have been a few tractors that have used them. I wish it was an option over hydrostatic transmissions.
pokeymcsnatch 3y ago
Truck manufacturers measure fuel efficiencies to the tenths and compete on that. At highway speeds, ICE engines win over a pure electric system, so throwing in another conversion step hurts. For city routes, pure electric is better than diesel-electric. So in general, the disadvantages of a diesel-electric system outweigh any advantages when you take a look at how trucks operate. New trucks have "automatic" transmissions (not torque converters- they're more like automatically shifting standard transmissions), so no manual shifting required. Somewhat related, but refrigerated trailers ("refers") often use a diesel-electric system because it's easy to plug in to shore power and cut the diesel engine.
- pixl97 3y ago
  A fair portion of large work trucks aren't moving all the time but require running. This is what Edison is shooting for currently. Jobs that have a lot of sitting, such as piles of things (ironically) in the oil industry and things in Welding applications. Municipal trucks can benefit by running full electric in sensitive areas. Pure electric just won't work for any sizable portion of trucks getting converted, grid requirements just can't be met.
abe_m 3y ago
These same guys are building a commercial heavy-haul, vocational targeted diesel-electric hybrid truck. Their plan is to run a diesel at about half the normal displacement, and have batteries for a few hundred km of range. The axles are e-axles with no mechanical connection from engine to axles. The guys that started the company are heavy-haul truckers, and they think they've found some niches were the diesel-electric would shine.
dzhiurgis 3y ago
I think we are at the point where batteries are cheaper than generators hence it makes no economical sense…
- Turskarama 3y ago
  Cheaper maybe, but the weight is significant to the point that federal laws have to allow higher weights for battery electric trucks to make them viable. The biggest problem isn't the truck itself though, it's charging it. A single truck requires as much energy as a dozen cars meaning that a truck fast charger is going to need the equivalent of an entire bay of car fast chargers, and they require charging significantly more often. A car can get 95% of it's charging done at home overnight, whereas a battery electric truck is likely to need fast charging several times a day. The most convenient place to put these chargers would be at the loading bays where trucks pick up and drop off trailers, but these are generally not owned by the trucking company so the owner has little incentive to drop hundreds of thousands or even millions of dollars on chargers to save the trucking company money _sometimes_.
  - dzhiurgis 3y ago
    Oh the savings are far from "sometimes" and more like "save 90% from TCO". But you're quite right with regards of charging stops. It's almost a catch-22, but fortunately stations are relatively easy to build.
SigmundA 3y ago
Mechanical transmission are in the high 90's percent efficient at highway speed, almost no losses. Diesel Electric transmissions in trains are in the 80's percent efficient range, double conversion from mechanical to electrical back to mechanical has higher losses. Trains make up for this with lower rolling and aero resistance, they need the precise traction control of the electric transmission to prevent wheel slip along with the impracticality of mechanically routing power to the wheels. Semis do not have this issue.
- Turskarama 3y ago
  I suspect modern diesel electric drivetrains are probably in the low 90's, especially with a lithium battery in the middle acting as a buffer so there's never any over-production by the generators. Even if trucks do spend the majority of their time on the highway, it's not all of the time and the efficiency gains every time they need to stop and start are significant.
  - ZeroGravitas 3y ago
    Re-gen likely gets it back over 100% again though.

starbase 3y ago

agreed. diesel-electric powertrain has a specific meaning, and this ain't it. this is a diesel hybrid

Turskarama 3y ago
I'm pretty sure it IS actually diesel electric, the engine is only used as a generator with no direct connection to the wheels. It's a full time battery-electric drive with a range extender.

theossuary 3y ago

Yeah I did some research on this a while ago because I had the same thought, diesel/electric drive-train seems like a no-brainer for trucks, and maybe even other vehicles. Basically a generator in an electric drive-train, with the possibility of introducing batteries too. Sadly the main drawback seems to be cost; as is evident in the pricing of the startup's product. More than that, until gasoline vehicle externalities are properly priced in, the cost of any alternative will be exorbitant in comparison. There have been some concept vehicles, and larger commercial vehicles; but they never caught on. It seems like electric will win before diesel/electric has a real chance. I always thought it'd make the most sense on motor homes and the like, where people tend to bring a small generator for electric appliances anyway. https://wikicars.org/en/Diesel-Electric_Hybrid https://wikicars.org/en/Diesel-Electric_Hybrid

pixl97 3y ago
Electric cannot win in semi applications for the foreseeable future. We'd need many more terawatts of power in the to supply their needs.

vvanders 3y ago

Yeah, I think there have been a few tractors that have used them. I wish it was an option over hydrostatic transmissions.

pokeymcsnatch 3y ago

Truck manufacturers measure fuel efficiencies to the tenths and compete on that. At highway speeds, ICE engines win over a pure electric system, so throwing in another conversion step hurts. For city routes, pure electric is better than diesel-electric. So in general, the disadvantages of a diesel-electric system outweigh any advantages when you take a look at how trucks operate. New trucks have "automatic" transmissions (not torque converters- they're more like automatically shifting standard transmissions), so no manual shifting required. Somewhat related, but refrigerated trailers ("refers") often use a diesel-electric system because it's easy to plug in to shore power and cut the diesel engine.

pixl97 3y ago
A fair portion of large work trucks aren't moving all the time but require running. This is what Edison is shooting for currently. Jobs that have a lot of sitting, such as piles of things (ironically) in the oil industry and things in Welding applications. Municipal trucks can benefit by running full electric in sensitive areas. Pure electric just won't work for any sizable portion of trucks getting converted, grid requirements just can't be met.

abe_m 3y ago

These same guys are building a commercial heavy-haul, vocational targeted diesel-electric hybrid truck. Their plan is to run a diesel at about half the normal displacement, and have batteries for a few hundred km of range. The axles are e-axles with no mechanical connection from engine to axles. The guys that started the company are heavy-haul truckers, and they think they've found some niches were the diesel-electric would shine.

dzhiurgis 3y ago

I think we are at the point where batteries are cheaper than generators hence it makes no economical sense…

Turskarama 3y ago
Cheaper maybe, but the weight is significant to the point that federal laws have to allow higher weights for battery electric trucks to make them viable. The biggest problem isn't the truck itself though, it's charging it. A single truck requires as much energy as a dozen cars meaning that a truck fast charger is going to need the equivalent of an entire bay of car fast chargers, and they require charging significantly more often. A car can get 95% of it's charging done at home overnight, whereas a battery electric truck is likely to need fast charging several times a day. The most convenient place to put these chargers would be at the loading bays where trucks pick up and drop off trailers, but these are generally not owned by the trucking company so the owner has little incentive to drop hundreds of thousands or even millions of dollars on chargers to save the trucking company money _sometimes_.
- dzhiurgis 3y ago
  Oh the savings are far from "sometimes" and more like "save 90% from TCO". But you're quite right with regards of charging stops. It's almost a catch-22, but fortunately stations are relatively easy to build.

SigmundA 3y ago

Mechanical transmission are in the high 90's percent efficient at highway speed, almost no losses. Diesel Electric transmissions in trains are in the 80's percent efficient range, double conversion from mechanical to electrical back to mechanical has higher losses. Trains make up for this with lower rolling and aero resistance, they need the precise traction control of the electric transmission to prevent wheel slip along with the impracticality of mechanically routing power to the wheels. Semis do not have this issue.

Turskarama 3y ago
I suspect modern diesel electric drivetrains are probably in the low 90's, especially with a lithium battery in the middle acting as a buffer so there's never any over-production by the generators. Even if trucks do spend the majority of their time on the highway, it's not all of the time and the efficiency gains every time they need to stop and start are significant.
- ZeroGravitas 3y ago
  Re-gen likely gets it back over 100% again though.