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Could you elaborate further? A hybrid, by definition, combines an ICE and electric drivetrain. While I understand it could be designed for a more efficient ran

by bumby 1y ago

Could you elaborate further? A hybrid, by definition, combines an ICE and electric drivetrain. While I understand it could be designed for a more efficient range of operation* how could it negate the downsides of an ICE-only design if it requires an ICE? (Are we conflating EV and hybrid?) * This also means each segment is less globally efficient, meaning the system is less efficient if it has to limp along if one part is inoperable

vel0city 1y ago
The pure ICE transmission is probably far more mechanically complicated than the transmission of a series hybrid. The pure ICE engine and transmission has to deal with some of the most stressful times the motor can handle, extremely high torque demands coming from a stop. Its far less stressful for an electric motor to generate good torque at such low RPMs. Just two quick examples.
- bumby 1y ago
  I think you’re still conflating EVs and hybrids. A hybrid has an ICE that is distinct from the mechanical transmission. Hybrids tend to run off the ICE at high speeds because it’s more efficient and use the ICE to charge the battery.
  - vel0city 1y ago
    > A series hybrid A key part of my original statement. A series hybrid or parallel series hybrid will often have a far simpler transmission in terms of moving parts and what not. You're right, they'll use the gas motor for power going highway speeds, but they're still a lot simpler. Many hybrids effectively only have a single speed for the ICE motor in their "transmission", some have 2-4, compared to modern ICE transmissions which are like 7+ gears. Note, I do agree, there are some hybrid drive trains that are more complicated than their ICE counterparts, but it is not a given. Many hybrids are a good bit simpler in the end. One example of a simpler setup would be Toyota's Hybrid Synergy Drive. e-CVT's can be radically simpler mechanically. https://en.wikipedia.org/wiki/Hybrid_Synergy_Drive https://en.wikipedia.org/wiki/Hybrid_Synergy_Drive
    - bumby 1y ago
      Yes, that’s why I put deliberately put “series” in my original post. The math is clear: in series, the system reliability cannot be greater than any single part. So if the claim is that hybrids are more reliable than ICE, there needs to be some sort of discussion about why you think the ICE is more reliable. You keep bringing up transmissions when the main point is related to the ICE.
      - Retric 1y ago
        Transmissions are required for ICE vehicles they aren’t required for hybrids. It’s one of the many failure points that can be removed. As to in series being more complicated, starter/alternator + battery already has all the mechanical complexity of a barebones series hybrid. You could technically take a standard ICE car change only electronics and get some of the benefits of a hybrid. Obviously for reliability you’d want beefier electric motors, and … before you know it you’re building a more robust system than a pure ICE.
        bumby 1y ago
        Yes, so the claim is that the complexity electric motors + batteries + planetary gears + all the ICE/electric interfaces are more reliable than a traditional transmission. I’m open to that argument but nobody has really elaborated in detail. Admittedly, I’m slightly skeptical (at least in the case of a manual gearbox) but would like to hear more detail.
        vel0city 1y ago
        > at least in the case of a manual gearbox Ok, let's say you go stupid simple for the transmission and have a super basic classic four-speed manual. Right off the bat, you've got clutch wear. In that e-CVT, there are no sliding clutches. Everything is connected all the time. Immediately, we see a wear component that will eventually need replacing. Not might need replacing, will need replacing. It is a consumable part, designed to wear. You now have cable assemblies which will eventually stretch over the life of the car. Those will eventually need adjustment. Once again, these just don't exist at all with the e-CVT system. Now you have a shifter and gear selector. This will need to slip in and out of other gears. Often this is not a perfect shift, imparting wear on the transmission components. Once again, you don't have a gear selector in an e-CVT, this wear never happens. This wear can cause premature failure of the transmission. This is largely controlled by the skill of the operator, sure. Just a few quick examples. But this is then also an incredibly basic manual transmission, you won't find such a thing on pretty much any recent mass market car. These days you'll see complicated automatics with servos and what not to control the gear ratios, massively more gear ratios, rely on fluid channels to push things around inside, rely on computers to operate them effectively, etc. And as Retric mentioned, there are analoges for most of the hybrid components in a pure-ICE car. You already have a DC motor set to drive the car in the starter motor. You already have an inverter, the alternator. You're not really adding a ton of new things, you're just massively upsizing some of the things you already have and massively simplifying a lot of the other components.
enragedcacti 1y ago
The design of a powersplit hybrid (like a Prius) allows for consolidation and elimination of a number of common failure items on a traditional ICE vehicle. - pure ICE needs mechanical gears or a belt-style CVT. a HV power source and 2 electric motors enable the use of a dead simple planetary gear set to change the ratio between ICE and the wheels. - ICE needs a starter and an alternator. psd hybrids use the existing electric motors and a dc-dc converter to do those jobs - belt powered components (e.g. A/C, power steering) are replaced by more reliable electric versions powered by the high voltage battery - ICE needs small displacement, high compression, turbo'd engines to meet power and efficiency targets. Hybrids can get away with wheezy but efficient and reliable low-compression engines because the electric motors make performance acceptable - ICE cars need to run their engine anytime they are moving. Hybrids will have 20+% lower runtime and that runtime will be spent at optimal RPMs and with minimal stress as bursts in acceleration are assisted by the electric motor.

by bumby 1y ago

vel0city 1y ago

The pure ICE transmission is probably far more mechanically complicated than the transmission of a series hybrid. The pure ICE engine and transmission has to deal with some of the most stressful times the motor can handle, extremely high torque demands coming from a stop. Its far less stressful for an electric motor to generate good torque at such low RPMs. Just two quick examples.

bumby 1y ago
I think you’re still conflating EVs and hybrids. A hybrid has an ICE that is distinct from the mechanical transmission. Hybrids tend to run off the ICE at high speeds because it’s more efficient and use the ICE to charge the battery.
- vel0city 1y ago
  > A series hybrid A key part of my original statement. A series hybrid or parallel series hybrid will often have a far simpler transmission in terms of moving parts and what not. You're right, they'll use the gas motor for power going highway speeds, but they're still a lot simpler. Many hybrids effectively only have a single speed for the ICE motor in their "transmission", some have 2-4, compared to modern ICE transmissions which are like 7+ gears. Note, I do agree, there are some hybrid drive trains that are more complicated than their ICE counterparts, but it is not a given. Many hybrids are a good bit simpler in the end. One example of a simpler setup would be Toyota's Hybrid Synergy Drive. e-CVT's can be radically simpler mechanically. https://en.wikipedia.org/wiki/Hybrid_Synergy_Drive https://en.wikipedia.org/wiki/Hybrid_Synergy_Drive
  - bumby 1y ago
    Yes, that’s why I put deliberately put “series” in my original post. The math is clear: in series, the system reliability cannot be greater than any single part. So if the claim is that hybrids are more reliable than ICE, there needs to be some sort of discussion about why you think the ICE is more reliable. You keep bringing up transmissions when the main point is related to the ICE.
    - Retric 1y ago
      Transmissions are required for ICE vehicles they aren’t required for hybrids. It’s one of the many failure points that can be removed. As to in series being more complicated, starter/alternator + battery already has all the mechanical complexity of a barebones series hybrid. You could technically take a standard ICE car change only electronics and get some of the benefits of a hybrid. Obviously for reliability you’d want beefier electric motors, and … before you know it you’re building a more robust system than a pure ICE.
      - bumby 1y ago
        Yes, so the claim is that the complexity electric motors + batteries + planetary gears + all the ICE/electric interfaces are more reliable than a traditional transmission. I’m open to that argument but nobody has really elaborated in detail. Admittedly, I’m slightly skeptical (at least in the case of a manual gearbox) but would like to hear more detail.
        vel0city 1y ago
        > at least in the case of a manual gearbox Ok, let's say you go stupid simple for the transmission and have a super basic classic four-speed manual. Right off the bat, you've got clutch wear. In that e-CVT, there are no sliding clutches. Everything is connected all the time. Immediately, we see a wear component that will eventually need replacing. Not might need replacing, will need replacing. It is a consumable part, designed to wear. You now have cable assemblies which will eventually stretch over the life of the car. Those will eventually need adjustment. Once again, these just don't exist at all with the e-CVT system. Now you have a shifter and gear selector. This will need to slip in and out of other gears. Often this is not a perfect shift, imparting wear on the transmission components. Once again, you don't have a gear selector in an e-CVT, this wear never happens. This wear can cause premature failure of the transmission. This is largely controlled by the skill of the operator, sure. Just a few quick examples. But this is then also an incredibly basic manual transmission, you won't find such a thing on pretty much any recent mass market car. These days you'll see complicated automatics with servos and what not to control the gear ratios, massively more gear ratios, rely on fluid channels to push things around inside, rely on computers to operate them effectively, etc. And as Retric mentioned, there are analoges for most of the hybrid components in a pure-ICE car. You already have a DC motor set to drive the car in the starter motor. You already have an inverter, the alternator. You're not really adding a ton of new things, you're just massively upsizing some of the things you already have and massively simplifying a lot of the other components.

enragedcacti 1y ago

The design of a powersplit hybrid (like a Prius) allows for consolidation and elimination of a number of common failure items on a traditional ICE vehicle. - pure ICE needs mechanical gears or a belt-style CVT. a HV power source and 2 electric motors enable the use of a dead simple planetary gear set to change the ratio between ICE and the wheels. - ICE needs a starter and an alternator. psd hybrids use the existing electric motors and a dc-dc converter to do those jobs - belt powered components (e.g. A/C, power steering) are replaced by more reliable electric versions powered by the high voltage battery - ICE needs small displacement, high compression, turbo'd engines to meet power and efficiency targets. Hybrids can get away with wheezy but efficient and reliable low-compression engines because the electric motors make performance acceptable - ICE cars need to run their engine anytime they are moving. Hybrids will have 20+% lower runtime and that runtime will be spent at optimal RPMs and with minimal stress as bursts in acceleration are assisted by the electric motor.