3 ms·

>Regarding efficiency, I think this is a smaller issue than it seems. Let's say a chain is 95% efficient and their system is 85% efficient (they claim 5% less e

>Regarding efficiency, I think this is a smaller issue than it seems. Let's say a chain is 95% efficient and their system is 85% efficient (they claim 5% less efficient than a chain, apparently, but I'm sure that's a stretch). Would be interesting to see proof of their efficiency claims, having looked into this before series hybrid drivetrains are in the 80% efficiency range, you have generator->charge controller->motor controller->motor losses. There are no production series hybrids I am of aware of in automobiles, all hybrid seem to have a parallel component connecting engine to wheels at highways speeds because its much more efficient. Trains and large boats do diesel electric drivetrains but its not for running efficiency but other factors like traction /throttle control and power routing. Its very difficult to out perform a mechanical drivetrain in both weight and efficiency if your power source is mechanical (ICE / human body).

skykooler 4y ago
> There are no production series hybrids I am of aware of in automobiles Would not the Chevy Volt count? The gasoline engine only serves as a generator, it is not mechanically connected to the wheels.
- wolrah 4y ago
  > The gasoline engine only serves as a generator, it is not mechanically connected to the wheels. The Volt can operate in a series hybrid mode, but there is also a mechanical connection that is engaged at certain speeds where it's more efficient to just direct drive rather than double-convert the energy from the combustion engine.
kevin_thibedeau 4y ago
> There are no production series hybrids I am of aware of in automobiles The Chevy Volt was the first production series hybrid.
- SigmundA 4y ago
  Volts have a mechanical connection: https://www.gm-volt.com/threads/gen-2-volt-transmission-operating-modes-explained.337644/ https://www.gm-volt.com/threads/gen-2-volt-transmission-oper...
ZeroGravitas 4y ago
BMW i3 has an optional range extender Which is a motorcycle engine that only generates power. Nissan e-power cars are hybrids that you can't plug in, but all power is generated by the ICE and then fed to the electric motor before it gets to the wheels.
- SigmundA 4y ago
  I guess I think the i3 doesn't count since its only a 34hp engine so it can't really power the car in normal driving (without sitting and letting the battery recharge for a while) its just a range extender but yes it is technically a series hybrid. It also has pretty poor efficiency using gas (31 mpg combined) The Nissan e-power is interesting, having not dug deep into it before, it looked like it obviously had a engine to wheel connection through the transfer case. Thought they where pulling a Chevy and claiming series hybrid when actually parallel, but just digging deeper its very strange the engine output and drive gear are separated only by MM as though they where leaving the design open to a mechanical connection. Never the less its difficult to get highway MPG numbers on it which is why most hybrids have a mechanical connection. Electric is more efficient stop and go city driving while steady state highway mechanical transfer is more efficient. Would like to see power loss numbers and highway mpg, my guess is on the highway the E-Power would lose out to a Prius.
  - jasonwatkinspdx 4y ago
    You are mistaken about the i3. Some friends had one and I joined them on several road trips. Driving it long distances is no different than any other car. You just stop and fill up the tank every few hours. The range extender pops on as needed to keep the battery from fully drawing down. It's important to remember it doesn't actually take that much horsepower to just keep a car putting along at reasonable speeds. Even economy engines are oversized compared to that due to the need for good low end torque in start/stop conditions. But a hybrid solves that the other way.
    - SigmundA 4y ago
      Although less of an issue than I thought there are driving conditions where it cannot maintain speed due to lack of power, it was a big enough issue for class action lawsuit to be filed over it dropping to 45mph on the highway: https://www.greencarreports.com/news/1105823_bmw-i3-rex-range-extender-owner-assesses-pros-and-cons-of-limited-power-engine https://www.greencarreports.com/news/1105823_bmw-i3-rex-rang... And again my main point was on efficiency, I would hope you agree 31mpg combined is extremely poor for a 34hp engine when much larger engines get much better mileage and have no issues with providing power when needed without battery assistance. It doesn't need much hp to maintain highway speed (probably around 34hp on flat ground) which means the engine is running full throttle to do so, vs running in it most efficient range which is not where it puts out peak power. The e-power Nissan has a full size engine, but a small battery, although would be interesting to compare it drivetrains weight with a standard one, having both a electric motor and generator of equal size is typically much heavier than a transmission.
throwawayboise 4y ago
Trains do it because they need to apply a lot of torque at zero speed to get moving. The only way to do that with a mechanical connection to a combustion engine is with a clutch, which would burn up from friction before the train got going. In theory a hydraulic pump would work, but I'm sure that electric motors are better for that usage, since that is what they use.
- jasonwatkinspdx 4y ago
  There's also torque converters, which are a hydraulic mechanism. This is the basis of most (non sporting) automatic transmissions. Higher performance torque converters have a lock up mechanism that functions as a clutch making it rigid at high speeds. So you can kinda get both.
  - masklinn 4y ago
    > There's also torque converters, which are a hydraulic mechanism. This is the basis of most (non sporting) automatic transmissions. By virtue of being the dominant automatic transmission in the US, where automatic transmission is the overwhelming majority. In Europe, torque converters have never been much of a thing, historically because of the small engines (at the low end, and demand for control and responsiveness at the high end), and more recently for efficiency reasons. AT has been shooting up in popularity (in parts because gearings have been getting shorter which makes manual transmissions really annoying), but mostly on the back of DCTs, even at the low end e.g. these days it's pretty common to find a 6-speed DCT on a B-segment car, and C-segments getting 7 or 8-speed DCTs (AMTs sadly still survive at the lower end of AT, but I feel CVTs are eating their bacon, especially with progressive hybridation).
    - SigmundA 4y ago
      Modern lock-up torque converter transmissions have pretty much eliminated any efficiency gains from other designs, I believe everyone is moving to them even in Europe. I know here in the US many care from various manufacturer are coming with German designed ZF transmissions including the 9 speed in my Honda Pilot. https://www.autocar.co.uk/car-news/technology-news/under-skin-why-torque-converters-are-coming-back-dead https://www.autocar.co.uk/car-news/technology-news/under-ski... https://www.caranddriver.com/features/a23367341/automatic-transmission-best-zf-eight-speed/ https://www.caranddriver.com/features/a23367341/automatic-tr...

skykooler 4y ago

> There are no production series hybrids I am of aware of in automobiles Would not the Chevy Volt count? The gasoline engine only serves as a generator, it is not mechanically connected to the wheels.

wolrah 4y ago
> The gasoline engine only serves as a generator, it is not mechanically connected to the wheels. The Volt can operate in a series hybrid mode, but there is also a mechanical connection that is engaged at certain speeds where it's more efficient to just direct drive rather than double-convert the energy from the combustion engine.

kevin_thibedeau 4y ago

> There are no production series hybrids I am of aware of in automobiles The Chevy Volt was the first production series hybrid.

SigmundA 4y ago
Volts have a mechanical connection: https://www.gm-volt.com/threads/gen-2-volt-transmission-operating-modes-explained.337644/ https://www.gm-volt.com/threads/gen-2-volt-transmission-oper...

ZeroGravitas 4y ago

BMW i3 has an optional range extender Which is a motorcycle engine that only generates power. Nissan e-power cars are hybrids that you can't plug in, but all power is generated by the ICE and then fed to the electric motor before it gets to the wheels.

SigmundA 4y ago
I guess I think the i3 doesn't count since its only a 34hp engine so it can't really power the car in normal driving (without sitting and letting the battery recharge for a while) its just a range extender but yes it is technically a series hybrid. It also has pretty poor efficiency using gas (31 mpg combined) The Nissan e-power is interesting, having not dug deep into it before, it looked like it obviously had a engine to wheel connection through the transfer case. Thought they where pulling a Chevy and claiming series hybrid when actually parallel, but just digging deeper its very strange the engine output and drive gear are separated only by MM as though they where leaving the design open to a mechanical connection. Never the less its difficult to get highway MPG numbers on it which is why most hybrids have a mechanical connection. Electric is more efficient stop and go city driving while steady state highway mechanical transfer is more efficient. Would like to see power loss numbers and highway mpg, my guess is on the highway the E-Power would lose out to a Prius.
- jasonwatkinspdx 4y ago
  You are mistaken about the i3. Some friends had one and I joined them on several road trips. Driving it long distances is no different than any other car. You just stop and fill up the tank every few hours. The range extender pops on as needed to keep the battery from fully drawing down. It's important to remember it doesn't actually take that much horsepower to just keep a car putting along at reasonable speeds. Even economy engines are oversized compared to that due to the need for good low end torque in start/stop conditions. But a hybrid solves that the other way.
  - SigmundA 4y ago
    Although less of an issue than I thought there are driving conditions where it cannot maintain speed due to lack of power, it was a big enough issue for class action lawsuit to be filed over it dropping to 45mph on the highway: https://www.greencarreports.com/news/1105823_bmw-i3-rex-range-extender-owner-assesses-pros-and-cons-of-limited-power-engine https://www.greencarreports.com/news/1105823_bmw-i3-rex-rang... And again my main point was on efficiency, I would hope you agree 31mpg combined is extremely poor for a 34hp engine when much larger engines get much better mileage and have no issues with providing power when needed without battery assistance. It doesn't need much hp to maintain highway speed (probably around 34hp on flat ground) which means the engine is running full throttle to do so, vs running in it most efficient range which is not where it puts out peak power. The e-power Nissan has a full size engine, but a small battery, although would be interesting to compare it drivetrains weight with a standard one, having both a electric motor and generator of equal size is typically much heavier than a transmission.

throwawayboise 4y ago

Trains do it because they need to apply a lot of torque at zero speed to get moving. The only way to do that with a mechanical connection to a combustion engine is with a clutch, which would burn up from friction before the train got going. In theory a hydraulic pump would work, but I'm sure that electric motors are better for that usage, since that is what they use.

jasonwatkinspdx 4y ago
There's also torque converters, which are a hydraulic mechanism. This is the basis of most (non sporting) automatic transmissions. Higher performance torque converters have a lock up mechanism that functions as a clutch making it rigid at high speeds. So you can kinda get both.
- masklinn 4y ago
  > There's also torque converters, which are a hydraulic mechanism. This is the basis of most (non sporting) automatic transmissions. By virtue of being the dominant automatic transmission in the US, where automatic transmission is the overwhelming majority. In Europe, torque converters have never been much of a thing, historically because of the small engines (at the low end, and demand for control and responsiveness at the high end), and more recently for efficiency reasons. AT has been shooting up in popularity (in parts because gearings have been getting shorter which makes manual transmissions really annoying), but mostly on the back of DCTs, even at the low end e.g. these days it's pretty common to find a 6-speed DCT on a B-segment car, and C-segments getting 7 or 8-speed DCTs (AMTs sadly still survive at the lower end of AT, but I feel CVTs are eating their bacon, especially with progressive hybridation).
  - SigmundA 4y ago
    Modern lock-up torque converter transmissions have pretty much eliminated any efficiency gains from other designs, I believe everyone is moving to them even in Europe. I know here in the US many care from various manufacturer are coming with German designed ZF transmissions including the 9 speed in my Honda Pilot. https://www.autocar.co.uk/car-news/technology-news/under-skin-why-torque-converters-are-coming-back-dead https://www.autocar.co.uk/car-news/technology-news/under-ski... https://www.caranddriver.com/features/a23367341/automatic-transmission-best-zf-eight-speed/ https://www.caranddriver.com/features/a23367341/automatic-tr...