3 ms·

Such a setup is vastly less efficient for small engines. If the combusion engine is turning, the best way to use that power is directly to the wheels, as oppos

Such a setup is vastly less efficient for small engines. If the combusion engine is turning, the best way to use that power is directly to the wheels, as opposed converting it back and forth to electricity.

Dennip 2y ago
It would be interesting to see the numbers I guess. For one, the manufacturer is offloading that energy burden onto the owner, not themselves. IIRC A large portion of the carbon created by a car is during the manufacture, so if you're not forging a prop shaft and machining a gearbox, is it acceptable to reduce engine efficiency by some measure? Especially given the engine won't run all the time, just when the battery drop to some margin the car feels it should start charging. Potentially (theorising here) Your EV will last longer before getting crushed into a cube, as it can compensate for battery degradation, your engine will last longer as it will have a fairly stable usage load (revs etc) and won't be used much
_visgean 2y ago
my understanding was that you can run the gas engine in optimal speed to charge the electric engine which makes it more efficient.
- bluGill 2y ago
  You can also add more gears in the transmission to make it more efficient as well. Gears are very efficient than conversion to/from electric (that is a series model, not even charging a battery.) The only way to make this work is if the engine is very undersized - the more load an engine is under the higher the efficiency, with gears alone though you would end up with an engine that takes unacceptably long to get up to speed, and slows down when going uphill, or into a headwind. If you are going ICE to battery you can have that undersized engine, and make up the extra losses by using the battery when needed, hence a hybrid car.
bluGill 2y ago
Such a setup can be more efficient - but only if everything is tuned perfectly. ICE engines are generally most efficient at low RPM and high throttle settings (last time I saw the graphs it was 1950RPM at 87% throttle peaked at 43% efficient, but that was one particular engine: yours will be different) - so you the entire system tuned around this, mistakes mean you either are running lower throttle or spinning extra mass not needed. Very few companies have the ability to design an engine around their exact needs - only the large automakers can really pull it off and they typically trade engines with other auto makers so they can offer more engine options in their cars than they have designed.
- 4gotunameagain 2y ago
  > ICE engines are generally most efficient at low RPM and high throttle settings Which is why modern cars are much more likely to include a sixth gear -> drop the rpm, increase the torque = higher efficiency
- Dennip 2y ago
  I guess the principle would be that you just don't care. The cost savings of not designing a powertrain/gearbox, not manufacturing it, reduced moving parts needing maintenance, etc etc. The trade-off _might_ be worth it.
  - bluGill 2y ago
    The geabov is cheap to design compared to the engine. Not free but cheap.
WalterBright 2y ago
But isn't that the same as a diesel-electric locomotive, which is very efficient?
hwillis 2y ago
Not true. What a series hybrid does is give you big-engine power for small-engine efficiency. Pull onto the highway and you get 350 hp from the battery, which the engine recharges at a steady 50 hp. If you have a big engine you are only losing efficiency.
mapt 2y ago
This is not necessarily true, but it is often true for consumer car models that are already designed in quite complex ways around driveshaft power, with abundant compromises and costs. It's never "directly" transferred; Not even close. Something like an automatic transmission is a miracle of engineering perspicacity over the decades. If you're going to spend thousands of dollars including one based on driveshafts, then electric conversion looks a bit silly. In locomotives, some ships, and now tanks they're replacing the whole drivetrain with copper wire driven by an ICE alternator. Even with zero energy storage this permits a dramatic simplification of the vehicle, and often we're more than willing to pay the cost of mechanical->electric->mechanical conversion efficiency in exchange for losing a bunch of cams, gears, and 90 degree joints that each eat a little energy, take up space in the design, and weigh a significant amount. And it is very often the case that adding energy storage (a very simply bolt-on + software changes) permits dramatically reducing the size of the engine needed.
- sandworm101 2y ago
  Small engines are very different than big. They have very different needs re weight and complexity. A locomotive drive engine is basically mated to its power generating engine, moving in lockstep. Everything gets more complicated when one also wants to charge a battery. (Fyi, many locomotives have huge banks of resisters specifically for dumping energy into heat, which is not an option for cars.) Separating charge and power deliver requires two motors, a power-harvesting generator connected to the combustion engine and a separate drive motor. Those would need to be electrically separated since they would be always turning at different rates. That means totally separate charge and discharge circuitry, possibly even separate battery banks. Harvesting from the wheels might even require a third circuit to simultaneously charge from two sources. And the drive motor equipment would have to be sized large enough to cover the entire rated power output. Secondly, such a battery-in-line arrangement may create a battery-essential system whereby if the battery failed/discharged/overheated, the vehicle would just stop despite still having a working combustion engines. (The power direct from the generator may not be compatible with the drive motor.) Modern hybrids bypass all these problems by routing the IC engine to the wheels. The electrical system is then a single motor and an additional sprocket in the transmission. Power is then added or removed through a single motor and associated circuitry with no need to generate and provide electrical power simultaneously (F1 cars used to work like this). Add an extra differential, aka a "hybrid transmission", and you can run either motor alone or together (as in the Prius).

Dennip 2y ago

It would be interesting to see the numbers I guess. For one, the manufacturer is offloading that energy burden onto the owner, not themselves. IIRC A large portion of the carbon created by a car is during the manufacture, so if you're not forging a prop shaft and machining a gearbox, is it acceptable to reduce engine efficiency by some measure? Especially given the engine won't run all the time, just when the battery drop to some margin the car feels it should start charging. Potentially (theorising here) Your EV will last longer before getting crushed into a cube, as it can compensate for battery degradation, your engine will last longer as it will have a fairly stable usage load (revs etc) and won't be used much

_visgean 2y ago

my understanding was that you can run the gas engine in optimal speed to charge the electric engine which makes it more efficient.

bluGill 2y ago
You can also add more gears in the transmission to make it more efficient as well. Gears are very efficient than conversion to/from electric (that is a series model, not even charging a battery.) The only way to make this work is if the engine is very undersized - the more load an engine is under the higher the efficiency, with gears alone though you would end up with an engine that takes unacceptably long to get up to speed, and slows down when going uphill, or into a headwind. If you are going ICE to battery you can have that undersized engine, and make up the extra losses by using the battery when needed, hence a hybrid car.

bluGill 2y ago

Such a setup can be more efficient - but only if everything is tuned perfectly. ICE engines are generally most efficient at low RPM and high throttle settings (last time I saw the graphs it was 1950RPM at 87% throttle peaked at 43% efficient, but that was one particular engine: yours will be different) - so you the entire system tuned around this, mistakes mean you either are running lower throttle or spinning extra mass not needed. Very few companies have the ability to design an engine around their exact needs - only the large automakers can really pull it off and they typically trade engines with other auto makers so they can offer more engine options in their cars than they have designed.

4gotunameagain 2y ago
> ICE engines are generally most efficient at low RPM and high throttle settings Which is why modern cars are much more likely to include a sixth gear -> drop the rpm, increase the torque = higher efficiency
Dennip 2y ago
I guess the principle would be that you just don't care. The cost savings of not designing a powertrain/gearbox, not manufacturing it, reduced moving parts needing maintenance, etc etc. The trade-off _might_ be worth it.
- bluGill 2y ago
  The geabov is cheap to design compared to the engine. Not free but cheap.

WalterBright 2y ago

But isn't that the same as a diesel-electric locomotive, which is very efficient?

hwillis 2y ago

Not true. What a series hybrid does is give you big-engine power for small-engine efficiency. Pull onto the highway and you get 350 hp from the battery, which the engine recharges at a steady 50 hp. If you have a big engine you are only losing efficiency.

mapt 2y ago

This is not necessarily true, but it is often true for consumer car models that are already designed in quite complex ways around driveshaft power, with abundant compromises and costs. It's never "directly" transferred; Not even close. Something like an automatic transmission is a miracle of engineering perspicacity over the decades. If you're going to spend thousands of dollars including one based on driveshafts, then electric conversion looks a bit silly. In locomotives, some ships, and now tanks they're replacing the whole drivetrain with copper wire driven by an ICE alternator. Even with zero energy storage this permits a dramatic simplification of the vehicle, and often we're more than willing to pay the cost of mechanical->electric->mechanical conversion efficiency in exchange for losing a bunch of cams, gears, and 90 degree joints that each eat a little energy, take up space in the design, and weigh a significant amount. And it is very often the case that adding energy storage (a very simply bolt-on + software changes) permits dramatically reducing the size of the engine needed.

sandworm101 2y ago
Small engines are very different than big. They have very different needs re weight and complexity. A locomotive drive engine is basically mated to its power generating engine, moving in lockstep. Everything gets more complicated when one also wants to charge a battery. (Fyi, many locomotives have huge banks of resisters specifically for dumping energy into heat, which is not an option for cars.) Separating charge and power deliver requires two motors, a power-harvesting generator connected to the combustion engine and a separate drive motor. Those would need to be electrically separated since they would be always turning at different rates. That means totally separate charge and discharge circuitry, possibly even separate battery banks. Harvesting from the wheels might even require a third circuit to simultaneously charge from two sources. And the drive motor equipment would have to be sized large enough to cover the entire rated power output. Secondly, such a battery-in-line arrangement may create a battery-essential system whereby if the battery failed/discharged/overheated, the vehicle would just stop despite still having a working combustion engines. (The power direct from the generator may not be compatible with the drive motor.) Modern hybrids bypass all these problems by routing the IC engine to the wheels. The electrical system is then a single motor and an additional sprocket in the transmission. Power is then added or removed through a single motor and associated circuitry with no need to generate and provide electrical power simultaneously (F1 cars used to work like this). Add an extra differential, aka a "hybrid transmission", and you can run either motor alone or together (as in the Prius).