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>Hybrids have a lower TCO even though they have a higher initial purchase price. Is this conclusion based just on fuel consumption? From a relatability standpo

by bumby 1y ago

>Hybrids have a lower TCO even though they have a higher initial purchase price. Is this conclusion based just on fuel consumption? From a relatability standpoint, it doesn’t make sense at first blush because you have to have both ICE and EV parts in series in the drivetrain; the total reliability can’t be higher than the individual components of they’re in series.

vel0city 1y ago
Depending on the drive trains being compared, the hybrid drivetrain may be overall mechanically simpler than an ICE. A series hybrid can easily have fewer moving parts, fewer friction spots, less reliance on fluid motion through little channels, etc. And then you're also keeping the moving parts more in their happy zone of temperature, speed, and load instead of needing them to operate in as wide of conditions.
- 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.
  - 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

Depending on the drive trains being compared, the hybrid drivetrain may be overall mechanically simpler than an ICE. A series hybrid can easily have fewer moving parts, fewer friction spots, less reliance on fluid motion through little channels, etc. And then you're also keeping the moving parts more in their happy zone of temperature, speed, and load instead of needing them to operate in as wide of conditions.

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.
- 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.