4 ms·

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 par

by 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.
    - bumby 1y ago
      >there are analoges for most of the hybrid components in a pure-ICE car. The error in this is in assuming the analogs have equivalent reliability or cost in each system.* (The original point is about cost of ownership). They don’t. So, while both have batteries, the reliability and cost of each is very different. Same with the ICE component etc. My issue is broad generalizations about reliability without speaking to the nuance. I’m not set against the idea of a hybrid being more reliable or cheaper, but more against the superficial generalization. * also the analogs miss some of the complexity. Yes, both have a battery, but a hybrid requires high voltage and auxiliary batteries, meaning the battery system is by definition more complex.
      - vel0city 1y ago
        > The error in this is in assuming the analogs have equivalent reliability The majority of my comment points out how the equivalent analoge on the pure ICE is massively less reliable than the hybrid. Who is ignoring the reliability of the different components here again? Sure, there is a HV and a LV battery. They're both solid state devices and thus generally pretty reliable when it comes to cars. The LV battery faces far less wear. The overall system is considerably more reliable in the hybrid than the same in the ICE. It's near impossible to generally talk about the prices of something like the HV battery, it varies greatly based on what models you're talking about. One car might have a replacement used battery that's good for many years be $700, another might be extremely bespoke and rare and be $10k. If I were to judge prices of pure ICE transmissions based on extremely rare hyper cars I might say an ICE transmission replacement costs $20k or more. The details matter greatly when judging TCO on potentially low market cars.
        bumby 1y ago
        If your point is you can’t talk specifics about price of ownership, you’ve wasted both of our time during this entire discussion. That’s what it’s about. A better answer would have just been like the commenter below, who said the information is hard to come by. A hardliner stance where there’s a lot of uncertainty isn’t a great hill to die on.
  - Retric 1y ago
    > all the ICE/electric interfaces are more reliable than a traditional transmission The argument goes like this, ICE cars have an alternator (electric motor 1), starter (electric motor 2), battery, and transmission. A beefier alternator (generator) + starter (electric motor driving the car) + battery adds less complexity than a transmission. That’s the simplest EV design where the engine only ever charges the battery. It’s perfectly viable for a long range plug in hybrid that only ever uses the engine on long trips. The downside is batteries have conversion losses, so most hybrids have various ways of directly using engine power which then adds complexity. But ultimately hybrids are more complicated than EV’s but very much can be simpler than modern ICE cars. PS: Technically some old ICE designs like dynastart used to do the same as hybrids where the same electric motor acted as a starter and alternator but in modern ICE vehicles the tradeoff around now little time the starter is needed and how little power the alternator needs to generate means it’s more efficient to separate it out. http://www.isettadoc.com/files/dynastart.pdf http://www.isettadoc.com/files/dynastart.pdf
    - bumby 1y ago
      Thanks for taking the time to detail it. I think that’s a reasonable take. A couple caveats: 1) most modern hybrids use the ICE at higher speeds for efficiency, right? What does that mean in terms of added complexity and reliability? 2) somewhat of a tangent, but in the original post was regarding cost of ownership, and reliability was brought into the discussion because cost is a function of reliability. But the alternator vs electric motor aspect misses the original point about cost, considering the motor may cost 8x-10x to replace. All that to say, reliability and cost of ownership is complicated. I was pushing back on the overly simplistic takes and appreciate you adding some nuance.
      - Retric 1y ago
        > most modern hybrids use the ICE at higher speeds for efficiency, right? What does that mean in terms of added complexity and reliability? There’s a lot of tradeoffs involved which I’m not an expert on. However, ICE cars need an engine capable of low end torque and a good efficiency across a huge RPM range, hybrids can use a much simpler engine design optimized for where the engine operates best because the EV side handles the low end just fine. A hybrid engine is also used for fewer hours of operation over its lifespan so in general (because exceptions exist) the gas engine in an hybrid is more reliable than the gas engine in an equivalent ICE. That said, car manufacturers can use up that margin to save weight etc so it’s not a guarantee. In the end it’s a huge design space, saying something is a hybrid doesn’t actually tell you much about what’s under the hood.
vel0city 1y ago
> the main point is related to the ICE I didn't limit the original discussion to just an ICE motor versus an entire hybrid power train, I explicitly stated, "Depending on the _drive trains_ being compared, the hybrid _drivetrain_...". In the end people don't give a shit about if the motor is reliable, they care about if the car is reliable. The car, which includes a transmission and a heck of a lot more stuff in it. In the end the reliability of the drivetrain is more important, as that includes the reliability of the ICE and all the other stuff needed to make the car go. If you want to focus on just the ICE part, then sure mechanically the ICE motor in a hybrid drivetrain will be similarly designed to an ICE-only drivetrain. But an ICE car is more than just an ICE motor. And to have that ICE motor actually be useful, it needs to be paired with other components. As you've aptly stated, the reliability of the system overall is extremely related to the reliability of all the components. Namely, having more complicated and less reliable components anywhere in the system makes the whole system less reliable. Having to have an incredibly complicated transmission with tons of friction points and sliding parts and fluid channels relying on specific viscosities of oil is massively more complicated mechanically than a few fixed-ratio planetary gearsets. But guess what, even if you ignore the rest of the hybrid drive train and focus on just comparing the ICE motors, the ICE in a hybrid will probably outlive the ICE on a similar ICE-only car experiencing a similar usage pattern. The ICE in the hybrid with an e-CVT or similar will pretty much only exclusively operate in its most efficient and lowest stress ranges, while that pure-ICE vehicle needs that gas motor to work in every condition even if it is high stress. > there needs to be some sort of discussion about why you think the ICE is more reliable I don't think the ICE is more reliable than the hybrid. I've been arguing the opposite. The gas motor may be similarly reliable in a full ICE, but a lot of the other stuff around it becomes less reliable. Even then thinking about things like water pumps and AC compressors and what not, a lot of that gets to be more reliable working with their own extremely reliable DC motors going exactly the speed they want to go at instead of having to be tied to engine RPMs and belts and clutches and what not wherever they want to be instead of needing to be in the path of the belt. You don't have a wimpy barely sized alternator, you have a much more reliable AC motor/generator along with an inverter and well-sized battery supplying plenty of electrical power to the system which then has a much more stable voltage for your 12V system. You don't have to put nearly as much CCA load on your 12V battery, you won't run it down as much, it stays in its optimal voltage more often, etc.
enragedcacti 1y ago
you and Retric are using different definitions of "series". A "series hybrid" is a specific term describing a design that uses an ICE engine to generate electricity that powers an electric motor. This design replaces the transmission completely because the ICE rpm doesn't need to be matched to the wheel speed and the electric motor has a much wider RPM range. Many series hybrids do have a way to power the wheels directly with the engine at highway speeds but it's generally much simpler than a full transmission. Most Honda hybrids for instance have a single clutch that connects the ICE to a "6th" gear. > You keep bringing up transmissions when the main point is related to the ICE. less parts -> more reliability
- bumby 1y ago
  Ah, ok. I didn’t realize “series” is a specific term of art in the EV space. Thanks for clarifying. I was using it in the pure reliability domain sense (similar to the use in electrical circuits) >less parts -> more reliability This is the general heuristic but only true if the components in each system are equally reliable (and specific to the original claim about cost of ownership, equal in cost). I don’t think that’s true, and am asking for a nuanced breakdown. For example, the hybrid ICE may be more reliable for good reasons (eg consistent RPM). Or the traditional battery may have half the reliability, but 1/50th the cost. All of that factors into cost of ownership.
  - enragedcacti 1y ago
    > I don’t think that’s true, and am asking for a nuanced breakdown. In my experience this kind of nuanced info is unfortunately pretty hard to come by. MFGs know it but have no interest in sharing it. Same for taxi operators (though the number of hybrids in taxi fleets is pretty staggering). Fleet operators usually only look at the first 5 years so longer term maintenance and repairs aren't studied all that rigorously. That said, here's a 5-year fleet TCO analysis where HEVs on average were 6k cheaper than ICE: https://www.afla.org/news/692431/The-Hybrid-Value-Proposition-for-Fleets.htm https://www.afla.org/news/692431/The-Hybrid-Value-Propositio... Also, here is an analysis from 2016 showing that the 2005 Prius had the lowest 10 year maintenance cost of any model. Toyota had only been making hybrids for 7 years at that point. That level of reliability for a new technology is pretty impressive: https://www.greencarreports.com/news/1104478_toyota-prius-hybrid-is-cheapest-car-over-10-years-that-you-can-buy https://www.greencarreports.com/news/1104478_toyota-prius-hy... > (and specific to the original claim about cost of ownership, equal in cost). speaking to this piece, it can be hard to gauge because its not all that common for companies to sell very similar trims in hybrid and non-hybrid. The two PSD hybrid examples off the dome are the corolla which is +$1500 for hybrid and the first-gen maverick which was -$1100 for the hybrid (before Ford knew the hybrid would sell like hotcakes, then they cranked the price up). Perhaps Ford just wanted to burn cash but imo PSD hybrids are likely very competitive in terms of per unit cost, which would hopefully translate into lower repair costs. Toyota has also just switched to hybrid only for the Rav4, which is one of the best selling models on the planet. That would be a pretty bold move if they weren't very confident about the reliability and TCO (basically their entire brand value) or their ability to make money selling them (cost vs consumer value prop).

by bumby 1y ago

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.
  - bumby 1y ago
    >there are analoges for most of the hybrid components in a pure-ICE car. The error in this is in assuming the analogs have equivalent reliability or cost in each system.* (The original point is about cost of ownership). They don’t. So, while both have batteries, the reliability and cost of each is very different. Same with the ICE component etc. My issue is broad generalizations about reliability without speaking to the nuance. I’m not set against the idea of a hybrid being more reliable or cheaper, but more against the superficial generalization. * also the analogs miss some of the complexity. Yes, both have a battery, but a hybrid requires high voltage and auxiliary batteries, meaning the battery system is by definition more complex.
    - vel0city 1y ago
      > The error in this is in assuming the analogs have equivalent reliability The majority of my comment points out how the equivalent analoge on the pure ICE is massively less reliable than the hybrid. Who is ignoring the reliability of the different components here again? Sure, there is a HV and a LV battery. They're both solid state devices and thus generally pretty reliable when it comes to cars. The LV battery faces far less wear. The overall system is considerably more reliable in the hybrid than the same in the ICE. It's near impossible to generally talk about the prices of something like the HV battery, it varies greatly based on what models you're talking about. One car might have a replacement used battery that's good for many years be $700, another might be extremely bespoke and rare and be $10k. If I were to judge prices of pure ICE transmissions based on extremely rare hyper cars I might say an ICE transmission replacement costs $20k or more. The details matter greatly when judging TCO on potentially low market cars.
      - bumby 1y ago
        If your point is you can’t talk specifics about price of ownership, you’ve wasted both of our time during this entire discussion. That’s what it’s about. A better answer would have just been like the commenter below, who said the information is hard to come by. A hardliner stance where there’s a lot of uncertainty isn’t a great hill to die on.
- Retric 1y ago
  > all the ICE/electric interfaces are more reliable than a traditional transmission The argument goes like this, ICE cars have an alternator (electric motor 1), starter (electric motor 2), battery, and transmission. A beefier alternator (generator) + starter (electric motor driving the car) + battery adds less complexity than a transmission. That’s the simplest EV design where the engine only ever charges the battery. It’s perfectly viable for a long range plug in hybrid that only ever uses the engine on long trips. The downside is batteries have conversion losses, so most hybrids have various ways of directly using engine power which then adds complexity. But ultimately hybrids are more complicated than EV’s but very much can be simpler than modern ICE cars. PS: Technically some old ICE designs like dynastart used to do the same as hybrids where the same electric motor acted as a starter and alternator but in modern ICE vehicles the tradeoff around now little time the starter is needed and how little power the alternator needs to generate means it’s more efficient to separate it out. http://www.isettadoc.com/files/dynastart.pdf http://www.isettadoc.com/files/dynastart.pdf
  - bumby 1y ago
    Thanks for taking the time to detail it. I think that’s a reasonable take. A couple caveats: 1) most modern hybrids use the ICE at higher speeds for efficiency, right? What does that mean in terms of added complexity and reliability? 2) somewhat of a tangent, but in the original post was regarding cost of ownership, and reliability was brought into the discussion because cost is a function of reliability. But the alternator vs electric motor aspect misses the original point about cost, considering the motor may cost 8x-10x to replace. All that to say, reliability and cost of ownership is complicated. I was pushing back on the overly simplistic takes and appreciate you adding some nuance.
    - Retric 1y ago
      > most modern hybrids use the ICE at higher speeds for efficiency, right? What does that mean in terms of added complexity and reliability? There’s a lot of tradeoffs involved which I’m not an expert on. However, ICE cars need an engine capable of low end torque and a good efficiency across a huge RPM range, hybrids can use a much simpler engine design optimized for where the engine operates best because the EV side handles the low end just fine. A hybrid engine is also used for fewer hours of operation over its lifespan so in general (because exceptions exist) the gas engine in an hybrid is more reliable than the gas engine in an equivalent ICE. That said, car manufacturers can use up that margin to save weight etc so it’s not a guarantee. In the end it’s a huge design space, saying something is a hybrid doesn’t actually tell you much about what’s under the hood.

vel0city 1y ago

> the main point is related to the ICE I didn't limit the original discussion to just an ICE motor versus an entire hybrid power train, I explicitly stated, "Depending on the _drive trains_ being compared, the hybrid _drivetrain_...". In the end people don't give a shit about if the motor is reliable, they care about if the car is reliable. The car, which includes a transmission and a heck of a lot more stuff in it. In the end the reliability of the drivetrain is more important, as that includes the reliability of the ICE and all the other stuff needed to make the car go. If you want to focus on just the ICE part, then sure mechanically the ICE motor in a hybrid drivetrain will be similarly designed to an ICE-only drivetrain. But an ICE car is more than just an ICE motor. And to have that ICE motor actually be useful, it needs to be paired with other components. As you've aptly stated, the reliability of the system overall is extremely related to the reliability of all the components. Namely, having more complicated and less reliable components anywhere in the system makes the whole system less reliable. Having to have an incredibly complicated transmission with tons of friction points and sliding parts and fluid channels relying on specific viscosities of oil is massively more complicated mechanically than a few fixed-ratio planetary gearsets. But guess what, even if you ignore the rest of the hybrid drive train and focus on just comparing the ICE motors, the ICE in a hybrid will probably outlive the ICE on a similar ICE-only car experiencing a similar usage pattern. The ICE in the hybrid with an e-CVT or similar will pretty much only exclusively operate in its most efficient and lowest stress ranges, while that pure-ICE vehicle needs that gas motor to work in every condition even if it is high stress. > there needs to be some sort of discussion about why you think the ICE is more reliable I don't think the ICE is more reliable than the hybrid. I've been arguing the opposite. The gas motor may be similarly reliable in a full ICE, but a lot of the other stuff around it becomes less reliable. Even then thinking about things like water pumps and AC compressors and what not, a lot of that gets to be more reliable working with their own extremely reliable DC motors going exactly the speed they want to go at instead of having to be tied to engine RPMs and belts and clutches and what not wherever they want to be instead of needing to be in the path of the belt. You don't have a wimpy barely sized alternator, you have a much more reliable AC motor/generator along with an inverter and well-sized battery supplying plenty of electrical power to the system which then has a much more stable voltage for your 12V system. You don't have to put nearly as much CCA load on your 12V battery, you won't run it down as much, it stays in its optimal voltage more often, etc.

enragedcacti 1y ago

you and Retric are using different definitions of "series". A "series hybrid" is a specific term describing a design that uses an ICE engine to generate electricity that powers an electric motor. This design replaces the transmission completely because the ICE rpm doesn't need to be matched to the wheel speed and the electric motor has a much wider RPM range. Many series hybrids do have a way to power the wheels directly with the engine at highway speeds but it's generally much simpler than a full transmission. Most Honda hybrids for instance have a single clutch that connects the ICE to a "6th" gear. > You keep bringing up transmissions when the main point is related to the ICE. less parts -> more reliability

bumby 1y ago
Ah, ok. I didn’t realize “series” is a specific term of art in the EV space. Thanks for clarifying. I was using it in the pure reliability domain sense (similar to the use in electrical circuits) >less parts -> more reliability This is the general heuristic but only true if the components in each system are equally reliable (and specific to the original claim about cost of ownership, equal in cost). I don’t think that’s true, and am asking for a nuanced breakdown. For example, the hybrid ICE may be more reliable for good reasons (eg consistent RPM). Or the traditional battery may have half the reliability, but 1/50th the cost. All of that factors into cost of ownership.
- enragedcacti 1y ago
  > I don’t think that’s true, and am asking for a nuanced breakdown. In my experience this kind of nuanced info is unfortunately pretty hard to come by. MFGs know it but have no interest in sharing it. Same for taxi operators (though the number of hybrids in taxi fleets is pretty staggering). Fleet operators usually only look at the first 5 years so longer term maintenance and repairs aren't studied all that rigorously. That said, here's a 5-year fleet TCO analysis where HEVs on average were 6k cheaper than ICE: https://www.afla.org/news/692431/The-Hybrid-Value-Proposition-for-Fleets.htm https://www.afla.org/news/692431/The-Hybrid-Value-Propositio... Also, here is an analysis from 2016 showing that the 2005 Prius had the lowest 10 year maintenance cost of any model. Toyota had only been making hybrids for 7 years at that point. That level of reliability for a new technology is pretty impressive: https://www.greencarreports.com/news/1104478_toyota-prius-hybrid-is-cheapest-car-over-10-years-that-you-can-buy https://www.greencarreports.com/news/1104478_toyota-prius-hy... > (and specific to the original claim about cost of ownership, equal in cost). speaking to this piece, it can be hard to gauge because its not all that common for companies to sell very similar trims in hybrid and non-hybrid. The two PSD hybrid examples off the dome are the corolla which is +$1500 for hybrid and the first-gen maverick which was -$1100 for the hybrid (before Ford knew the hybrid would sell like hotcakes, then they cranked the price up). Perhaps Ford just wanted to burn cash but imo PSD hybrids are likely very competitive in terms of per unit cost, which would hopefully translate into lower repair costs. Toyota has also just switched to hybrid only for the Rav4, which is one of the best selling models on the planet. That would be a pretty bold move if they weren't very confident about the reliability and TCO (basically their entire brand value) or their ability to make money selling them (cost vs consumer value prop).