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Comment by cperciva | Hacker News Reader

which is the whole point of hybrids

Part of the point, not the whole point. Regenerative breaking is absolutely a win; but there can also be a significant benefit from allowing the ICE to remain in the RPM "sweet spot" rather than moving around a larger range.

View on HN

Another part of the point is that you can pack a much smaller and more efficient ICE and then substitute the missing power and torque from electric motors when needed. Most cars are not used at max power all the time. You need max power only at short times when accelerating. With pure ICE there is the tradeoff - a bigger engine will get you more max power / max torque but is going to be less fuel efficient because of internal friction.

On paper, yes, but did that ever happen? Sorry for being sarcastic, but where I live the frugal hybrid is exceptionally rare and the "same big engine, but driving a much heavier car" hybrid is omnipresent. The kind of people who might buy the frugal one buy second or third hand while almost all buyers of factory new pick the "same big engine" option, and those are the ones who decide what's available on the second hand market.

Yes, every single prius for example? The biggest engine that was produced with seems to be a ~100 bhp engine which isn't much for a 1.5 metric tonne car

In most countries, yes. Despite the push for SUV-styled cards (which are heavier than a regular city car, but not by that much), engines have been small.

Toyota Yaris - HSD - 1.5L 4cyl Renault Clio - E-Tech - 1.6L Hyundai Kona (SUV) - 1.6L Honda Jazz - 1.5L Peugeot 208 - 1.2L Peugeot 3008 (SUV) - 1.6L Peugeot 5008 (Family SUV) - 2L And the list goes on. Even BMW with it's xDrive puts out 1.5L engines.

Huge engines are only common in two places: sports cars (and even then, only a specific category like AMGs and friends, because even a Porsche 992 only has a 3L engine) and the US.

The info is useful, but those do not seem to be all that small. There were smaller engines available for the ICE version of the Clio, for example.

There was, and it was shit. The Cléon-Fonte, despite all my love for its BBBBRRRRRRRRRRVVVVVVVVVVV was becoming wildly insufficient for the already ever heavier cars simply due to electronics and safety measures, and it was already a 1.2L. The smallest ever put on a Clio was a .999L, and anyone driving a Twingo knows how it behaves the moment there's... a slight incline, or two people in the care.

1.5L is an incredibly small engine, especially when previous versions required much larger. The Renault Scénic IV is a 1.5 ton brick that is happily running on a 1.2L engine. The Scénic II's most sold motorization was a 2L engine.

I feel like I remember a pickup being available that was a 6L v8. So one cylinder in that engine had almost the same volume as all the cylinders in a 1.5L engine combined. That's pretty crazy to me.

edit: oh it was mine heh, my first car was a 1979 ford with a 460 ( 7.5L v8 ). It was a hand me down from my grandfather, he said if i could get it running i could have it.

A 6 liter 4-cylinder would have the same volume in a single cylinder as a 1.5L engine. A V8 of that size would have half the volume in a single cylinder, not almost the same volume.

A 1.5 liter is incredibly small. You’ll struggle to accelerate up slight inclines with that. If you’re in the mountains it will be even worse.

Fiat 500 hybrid 999cc engine, 69bhp (51kW).

I hired one on holiday and it worked fine. Maybe I'm getting old but I see less point in getting something that does 0-60 in 4 sec when most traffic goes from 0-40 in about two minutes and doesn't get much faster. It still has a top speed over 100mph.

Omoda 9 (SUV) is sold in Europe only as plug-in hybrid with small-ish 1.5L 143HP engine + 394HP electric (145km of pure electric range, 35kWh LFP battery).

https://en.wikipedia.org/wiki/Exeed_Yaoguang

The vast majority of hybrids use simulated atkinson cycle... while their cylinders might be the same size as N/A vehicles, they leave the intake valve open past the end of the stroke, so they effectively are displacing less, even though the cylinder dimensions might be the same size. The advantage is that atkinson cycle is more efficient. But it has too poor performance characteristics for an ICE-only car.

>On paper, yes, but did that ever happen?

Like absolutely, unless you consider 1.4L petrol engine large for something with over 170KW (over 220hp). Such kind of offerings are quite common at the East side of the pond.

I'd consider engines with HP in the two digits range not big. Few ICE cars (hybrid or not) are ever accelerated at the rate you could achieve with a 75 HP engine revved into the high but still safe range. People buy big engines so that they can get all their acceleration needs served at half throttle. And that's for stick shifting, those on automatic pick engine size so that they can accelerate on quarter throttle or else the car shifts back and it sounds all x "small engine working hard" (which would be so much less inefficient!).

Our family owned a Mercedes 240D (71 peak horsepower at sea level) for many years. That car's performance was lackluster on a good day and trying to merge onto the Pennsylvania Turnpike (with very short acceleration lanes) was IMO quite unsafe. From that experience, I'm pretty sure that people are dipping into more acceleration than that car could ever muster.

I have no doubt that some people behave as you describe, but I think some of that is driven from a rational position of not wanting to buy a car that is incapable of anything more than their normal daily driving. If you need to accelerate quickly to merge safely into traffic, bringing only 75 [or 71] peak horsepower to the table isn't a comfortable position to be in.

Hybrid one - 0-100km/h sub 7sec. The most important part is not 0-xxx but being able to take trucks in relatively short distances b/c most roads features just two lanes. Pressing pedal to the metal and engaging both engine does that.

The sub 100 power doesn't mean much if the engine has a turbine, e.g. TSI of volkswagen

Yes, check out BYD's hybrids. The petrol engine is 46% efficient, which is pretty damn amazing. This is more efficient than most power plants (combined cycle plants are better- but most power plants are not combined-cycle).

So what is the well to wheel efficiency of this vs. pure electric? There are fuel transportation losses in one, and transmission line losses in the other. In many cities electricity is quite a bit more expensive than gas so hybrids are a better deal financially.

Which cities are those? I can think of maybe a few in the Middle East with subsidized gasoline, but I’m coming up blank after that.

> did that ever happen?

In 2010 with the Chevrolet Volt.

Which only had a 1.4l engine. It was not as efficient as the gas only Prius but could be more efficient overall as the Volt of 2010 had a 40 mile EV range.

I think the question is "is that overall effect the reality, or do most people buy a very heavy hybrid?"

I wonder whether people actually understand that they need a smaller engine for the same performance?

Despite my overall low estimation of people's ability to fluidly reason about engineering tradeoffs, I think they generally do understand this one well enough, at least for the decisions that they will face. They're only deciding which car to buy, not what engine specifications are required to make a car successful in the market.

They go test-drive cars, probably glance at performance specifications and/or read/watch a test drive review of the cars. They can look at the 0-60mph/0-100 kph times and get a feel for "this car will be able to get out of its own way" vs "this car will be a rolling roadblock".

So "actually understand"? Maybe not, but "understand enough to guide their purchasing decision?" and therefore enough for the actual automobile product teams to design to accommodate? I think they do.

I've never seen a car where the hybrid and pure gas versions have the same size engine; the hybrid engine is almost always lighter and makes less power.

There’s a few luxury cars that use the same or larger engines for the hybrid. Lexus did it with the LS, hybrid 600h had a larger engine (5L) than the gas 460 (4.6L).

Those are super rare though.

Dunno if you consider plugin hybrids hybrids, but I believe the Audi Q5 PHEV and ICE-only engines are the same.

BMW i8

This reminds me of the short lived dilbert cartoon when Dilbert is complaining about how pokey his Prius, and when he hands the car over to Dogbert, he somehow is able to rip out of the parking lot at high speed.

Seriously though, hybrids seem like a bad compromise to just getting an EV. Hybrids have an electric drive train with an ICE drive train, and somehow that double complexity will be worth it? In the long run, EVs are winning on cost alone (especially in China where making cheap EVs is a thing).

And, you can make much lighter and lower range electric cars without all those heavy batteries, and boost the range with diesel when needed. Very attractive in principle. Most cars are not using their full range all the time, for a lot of people a 50 mile range car would be more than enough 98% of the time, but that remaining 2% means that people end up buying 200 mile range cars instead.

But then, do you end up removing enough battery weight to offset the weight of a whole ICE?

I thought about PHEV but in the end went full EV simply because it seemed to me with two whole power trains that's 2x the components to go wrong/need maintenance.

That's a common misconception, but hybrids are almost never as complicated as an ICE powertrain plus an EV powertrain. E.g. most hybrids are able to eliminate many parts that ICE vehicles require, like, starters, drive belts, multi-ratio transmissions, alternators, etc. Because of this, many hybrids surpass ICE-only vehicles in reliability.

That same insight applies to regular hybrids, and yet Toyota’s hybrids are legendary for their durability. There’s a reason half the cabs where I live are Prius station wagons, and it’s not their efficiency, judging by how they’re driven.

Consumer reports found that HEV's were the most reliable, and PHEV"s the least reliable. That's nonsensical, there's little difference between the two.

Toyota is the biggest seller of HEV's, Stellantis of PHEV. That's the difference. EV's on paper should be the most reliable, but Tesla is the biggest seller of those. If you want reliability, choose by brand rather than engine type.

I was comparing a Hyundai Ioniq EV with a Hyundai Ioniq PHEV and was surprised to find more problems reported by the owners of the Ioniq EV.

Mostly issues with 12V battery, it seemed like.

In the end I bought a Stellantis EV so I probably deserve everything I get - but they are cheap!

12V batteries dying in EVs has been a consistent problem. I think it got better for Tesla when they moved from lead acid to lithium ion for the 12V (like the much bigger battery).

>Consumer reports found that HEV's were the most reliable, and PHEV"s the least reliable. That's nonsensical, there's little difference between the two.

Eh, it's not so much nonsensical, as it is that you're just misinterpreting the data.

This conversation here is specifically about powertrain reliability, but that isn't what consumer reports measures. They measure complaints about any feature on the vehicle, including ancillary accessories unrelated to the vehicle's ability to transport people.

But also as you point out, shitty engineering (Stellantis's specialty) is a bigger issue than any particular drivetrain type.

Toyota's success with the Prius proves that this fear is unfounded. You will regularly find second hand prius models for sale with 500,000 km on the odometer.

Just think - if two drivetrains were less reliable, wouldn't you see that with the Prius?

You're right in principle, but it's important to remember that tradeoffs exist. You can very much trade off engineering effort and time to improve reliability.

Commercial aviation is a great example of taming extreme inherent unsafety of aircraft by applying a lot of resources to the engineering side. Another is space programs.

And car power trains have nothing on those ;) As Toyota has shown, it's totally possible to make reliable hybrid cars with enough engineering thrown at the problem.

So if all things were equal, you'd absolutely expect an EV to be more reliable than a hybrid, but all things are rarely equal.

In some ways it’s more complicated. The battery management and cooling is a point of failure. It’s also heavier and so wear and tear on suspension is greater.

On the other hand, a Toyota hybrid doesn’t have a gearbox at all, not even a CVT. Instead it has something similar to a differential, it’s mechanically simple and very reliable. It uses the electric motor in place of a turbo, so that’s another common failure point removed. It doesn’t have a starter motor, and the Atkinson cycle engine should suffer less stress than an equivalent petrol.

Practically the biggest problem is finding a 3rd party garage who will inspect the hybrid parts as part of a service.

This. This times 100x . Also, it’s not like each powertrain has an independent failure mode. If either break, your car is a brick until it’s fixed.

I have a friend who drives a Chevy Volt with a dead ICE engine; she just charges the battery and uses it as a (rather short range) pure EV vehicle. Not ideal, but it works for her until she gets something else.

If she was in California she wouldn't be able to pass smog at her next inspection, which is a funny problem considering she drives in pure EV mode now.

Oh I agree completely. I'm driving an old diesel now but I have no desire to get a hybrid, I'd get a pure EV if I were to buy a new car. But there are some tempting things in principle about plug-in hybrids

Smaller cars have always been available, but people have shown a preference for bigger cars where they can sit higher up, even though it costs them more.

I'm not talking about size, I'm talking about range and weight. You can have a huge car or a smaller car, going from a 90kWh battery pack to a 30kWh battery pack is gonna have the same weight saving in both

Maybe they should be at least charged for the catastrophic externalities that that "preference" results in.

does "preference" equate to endless, manipulative advertising from car manufacturers? Or, perhaps, the "preference" of higher profit margins from larger cars, pushing manufacturers to entirely abandon reasonably sized cars?

"Everyone who doesn't want what I want them to want has been brainwashed by corporate interests" is not a robust assertion under even the most casual scrutiny.

I hate to break it to you but something like a Rogue or HRV does circles around an Altima or Civic when it comes to daily flexibility and utility for a fairly paltry additional cost. It doesn't take a degree in rocket surgery to figure out why they fly off the shelves. For the average person they're a good combination of attributes.

The North American market now only includes a handful of sedans. Meanwhile, Hyundai and Toyota somehow manage to sell “tiny” cars in Korea, Japan and lots of developing countries.

A practical car is a station wagon, not an SUV, many of which have less storage space.

Please, cut the needless snark. People do buy vehicles for edge cases but the lack of smaller, practical vehicles is driven is large part by manufacturer profit.

Many of those tiny foreign cars are unfortunately not economically useful to sell in the regulated markets of the rich west, and even when they are they often aren't without the developing nation sales volume to amortize a lot of the fixed costs over.

I agree that there's a lot of stupidity going on when it comes to station wagons vs crossovers vs compact SUVs and the OEMs really do SUV-ify a lot of things that ought not to be.

The shape of these vehicles is fairly preordained by the nature of the fuel economy regulations and wind resistance and other regulations that apply equally to all of them. You're not gonna find "more space" in something like a Subaru Outback by squashing it on the vertical axis unless you stretch it in another dimension or find somewhere else to find space. Maybe you might be able to eek out a slightly better angle on the hatch or something but it ain't gonna be much. Fuel economy regulations make cars with thicc asses like the big sedans and station wagons of yesterday nonsensical.

The snark is not needless. It is tautologically impossible for the overwhelming majority of people do be "doing it wrong" on a matter that is in large part a subjective one of preference. If someone wants to assert that then I will talk down to them.

People buy these small SUVs left and right because they're seemingly the best option when it comes to well rounded boring A to B vehicles.

I think the crossover is pretty much the modern station wagon. I suppose they get marketed as SUV's but they're basically just a bit longer and taller car vs what I'd consider a "real" SUV; an enclosed truck chassis.

also once everybody else is obstructing your view with a bigger car it becomes necessary to have a bigger one, it's a race to the metaphorical bototm

This is the thing with good hybrids.

The "gas pedal" becomes a "I want to go faster/slower" pedal, its position has zero impact on the RPM.

As an anecdote: A security company I know only buys Toyota Hybrids for their guards just because of that. They have a habit of driving cars like they stole them and normal ICE cars break down from that kind of abuse. Hybrids won't let you abuse them, they pick the RPM and you deal with it.

(They also swap the passenger seat for a plastic box because the guards threw heavy crap like safety boxes on it, wearing down the seat in months)

This is less a hybrid thing and more a new transmission thing. It, of course, isn't free. The efficiency of a CVT is a good 10-20 percent lower than previous transmissions. That said, currently, the win from keeping the engine at either the max power or the max efficiency speed is substantial.

There are some really good videos out there going over how newer CVTs work. Looks like some people are working on ones that are teeth driven, to reduce the loss from being free belt driven. Borderline magical stuff, all told. (Obviously, not magic magic. But very very impressive designs.)

The post you commented on was talking about Toyota hybrids though, who don't use a CVT in the sense you're talking about.

They use a series-parallel hybrid transmission which is sometimes called eCVT, but works completely different from a classic CVT. There are no pullies, belts, chains, none of that. What they do have is a couple of motor-generators and a differential to link the system up with the engine and the drive shaft. No friction losses like CTVs have.

See https://prius.ecrostech.com/original/PriusFrames.htm, or look up "Hybrid Synergy Drive" on Wikipedia or Youtube or your favorite search engine.

Ah, totally fair in that this particular transmission is better than the belt driven CVT stuff. I had thought they were still a bit worse than other transmissions, but it looks like if they are, it is on the order of 1% or so.

Is fascinating to watch these things work.

I have a Subaru (ten years old w/ >200k miles on it's chain-type CVT), and I thought the justification for it was that it was more efficient than previous systems.

From a mechanical engineering standpoint, the Subaru CVT uses a fairly conventional lock-up torque converter at the input, but that gets locked as you pass something like 15-20 mph (once the lowest gear ratio is satisfactory w/o the torque converter function) and beyond that all shifting of the CVT is done w/ the torque converter locked. In addition, the clamping force of the sheaves is adjusted per the torque load of the transmission to minimize the frictional losses.

Anyway I'm curious about data comparing efficiency of conventional and CVT automatics.

My understanding is that the overall system is more efficient. It is only the transmission that is less so.

The videos online that look at various CVT systems is truly an amazing resource that I regret not having when I was younger. :D

If overall efficiency is what you see reflected in the EPA mileage numbers (or similar European tests), in what scenario would a lower efficiency transmission (lower Pout/Pin over some range of operating points?) lead to or even allow better overall efficiency?

I'm not sure I understand the question? You get the engine to hit its sweet spot and to hold it there. That gain outweighs the loss from the new transmission.

This would be similar to hitting the optimal torque point. The idea there would be that you can get out of the acceleration phase faster, so that you can transition to a more efficient gear to maintain the speed for longer.

The wikipedia looks to cover this well. One of the cites is specific on the efficiency of the CVT. I think I overstated how much higher the loss is, so maybe that is confusing things? I thought it was 10-20, but the cite on the page shows it solidly around 10.

Ah, thank you, I see the argument. I'm still a bit skeptical though when many non-CVT automatics are 6 or 8-speed models that there would be much "sweet spot" benefit left by being able to make relatively small changes in engine speed. Like many things probably depends on exactly what comparison is being made.

I mean, we are comparing 6-8 to effectively infinite? Question then comes into just how much is lost by being outside of the sweet spot for an engine. Which, I agree that I would not have thought it would be that big of a deal. Just going off modestly paying attention in my car, I see massive benefits keeping the car around 300 rpms lower.

Interestingly, my car gets better gas mileage around the 40ish speeds than I do at full highway speeds. That somewhat surprises me. It is very dependent on not having a heavy foot, of course.

Best efficiency speed can be understood by considering impact of fixed losses like HVAC, lights, computing, which consume more energy the longer you drive (so the total energy for those would be minimized by going faster) and the aerodynamic losses in which force goes with speed squared, power w/ speed cubed, energy over a fixed distance back to squared because at higher speeds time is reduced (this component is theoretically minimized by going very slowly). In between is rolling resistance which requires a fixed energy per distance, so it doesn't care about speed.

For EVs, the drivetrain efficiency is so high that it's variability with operating point doesn't affect this calculation much, and so the most efficient speed of an EV is around the speed at which the fixed losses equal the aero ones. This will vary greatly with environmental conditions since AC or heating load can be large in hot or cold conditions but at the right temperature will go to near zero.

In ICE cars, the drivetrain efficiency is much lower and so the drivetrain efficiencies are a much more significant part of the optimization problem, but the basic physics of the aerodynamics are the same.

The model I used to use in my head is that for an ICE, the most efficient operating point is probably around the lowest speed the car can operate in the highest gear, so maybe around 40 mph / 60 km/h? Obviously a rough heuristic though.

Generally speaking your car will get better fuel economy at 40mph than it will at 60 or 70mph. Your car gets so much more wind resistance the faster you go.

The main reason why city mileage is usually lower is because of all the stopping.

I think I just mentally had this idea shifted up about 10-15 mph. I'd expected 55 to be the sweet spot, for some reason.

Do all Toyotas do that? I'm pretty sure that my dad's Corolla will rev the engine when I press the gas if the engine is already running.

I'm also surprised for the first few minutes when I drive it how little "engine braking" it has (my habit is from riding a big motorbike).

Depends on the configuration. If they are equipped with a CVT+electric engine on the shaft, then that's the case: they rev to the sweet spot (which on gas engines is 4000-5000 rpm on acceleration? Depending on expected engine load I assume) and the speed is controlled by hydraulic force applied on the CVT.

With other hybrids: depends on the generator they have installed, but it matches the consumption in amps by the engine in order to "go" if it is not directly coupled with the transmission, or they just downshift to accelerate with help of the electric engine.

I am assuming a lot here: Toyotas (specially RAV4) mount CVTs among others, assuming pure electric generator by the ICE or coupled to it... So it depends a lot on specific configuration.

Even CVTs will rev the engine if you floor it, no? They typically allow for wanting to be in a few sweet spots. I prefer to keep it near the max efficiency speed. That said, my wife is a bit more aggressive and spends more time in the max power mark. It has a predictable change on the MPG reported by the vehicle.

I know for a fact you can neutral-drop a prius.

I know it's not exactly the same, but I was a teenager and curious, and you can rev them and shift into drive with some heel-toe finesse. Not sure if this works on the newer ones, this one was an early 2010s model.

Thank you for performing the experiment I didn’t even know I wanted to know the results of before now.

I performed many experiments on that family prius and with complete honestly, my experiments weren't even in the top ten worst things that car survived.

Trees, multiple motorcycles, final destination esque road debris, an accident that should have totalled it if not for an insurance mistake, leading to repairs worth more than the car. Three teenage drivers and two adult drivers with heavy feet. Not to mention many many hardware store runs hauling various sacks of yard materials, baby trees, lumber, etc.

My favorite times were rallying on compacted un-plowed snow. The thin tires and light weight meant it absolutely shredded.

It's my opinion that the Toyota Prius is one of the greatest vehicles ever built and they should be respected and feared.

That's an amazing testimony to its grit. I could stand to hear more of those stories over the appropriate beverage.

Dunno. My both Priuses did it and the company was specifically using the Yaris Hybrid.

Both will rev on neutral, but when the gear selector is on Drive there is no link between the pedal and RPM.

And on Brake it's even the opposite: above a certain speed, you press the accelerator and the RPM decreases to remove engine braking.

They're programmed to rev in situations like that, because people are used to it. Under normal operation, RPM is decided by power needs. If you start accelerating on the freeway, for example, the engine might jump from 1100 RPM to 3000 RPM with just some pedal, while a manual transmission obviously changes very little.

it's possible that the engine rev is just the speakers. a lot of cars are doing fake engine sounds.

The dash has an RPM gauge which moves. Also, the noise is horrendous, not sure why they would have chosen that when they could have used a nicer-sounding tone. This is a tame small car, not something you'd buy to impress your friends.

The whole "pas pedal" becomes faster/slower (one pedal driving) is coming to an end. Its being banned as default in the world's largest EV market (and largest EV export country).

Huh, that's interesting. Apparently China will be banning cars from having one-pedal driving as the default.

Losing muscle memory of pressing the brake pedal. Makes sense, actually.

I'm curious what you mean? I'm fairly confident the post you are responding to was only talking about newer transmissions. Which, I can't imagine those are going away?

The post is talking about most people drive with BEV , which is one pedal driving. My Tesla does one pedal driving my default.

China has banned "one pedal driving" as a default.

I took it to be people that are far more aggressive with the gas pedal than they really need to be. That is, it was more the heavy foot than it was letting off to brake.

Regardless, your point stands. People that have gotten used to not directly using brakes to indicate you are slowing down is a dangerous thing with how reliant we are on the standard indications that you are slowing. All the more so if you need to rapidly lose a ton of speed, where even regenerative brakes often fall back to friction.

> People that have gotten used to not directly using brakes to indicate you are slowing down is a dangerous thing with how reliant we are on the standard indications that you are slowing.

Most, if not all, EVs will light up the brake lights when you're slowing via regen braking as long as the deceleration rate is above a certain threshold. I know my Tesla does.

This addresses the signalling to the people behind you problem. You still should have the foot nearer the brake so that you can fully stop, if you need to do so rapidly.

Emergency brake systems probably help a lot with this problem, of course. Still seems wise to follow some of the older practices that we used to drill into people.

So you just type in the speed you want and hit enter?

> […] but there can also be a significant benefit from allowing the ICE to remain in the RPM "sweet spot" rather than moving around a larger range.

Which is why I'm surprised electric cars with range extenders aren't a bigger thing:

* https://en.wikipedia.org/wiki/Range_extender

Have the powertrain be all-electric, and have a battery pack, but for those with range anxiety have a small generator as an option that would go in the frunk (front truck). A (proverbial) small Honda EU2200i would be less maintenance than a traditional engine.

The EU2200i can sustain 15 amps. That charges most EVs at something like a few miles of range per hour. The biggest one that’s small enough for a frunk is the 3200i, which still only sustains 21.7 amps - plus, that’s from an L5-30R socket, so you’d need an adapter for the EV, and a custom chip to limit charging current below that, since the ones I’ve seen for that socket assume they can pull 24 amps.

Re: maintenance, small engines typically are pretty needy. That one wants an oil change, spark plug gap adjustment, and spark arrestor cleaning every 100 hours of use. The latter two are only usage-based, but the oil is time-based as well (6 months) since it oxidizes, and suffers from fuel dilution. Then there’s the fuel: god help you if you put ethanol gas into a small engine and let it sit for any period of time. It’s often difficult to find E0 fuel, and while there are external fuel tanks for generators that can hold quite a bit, they also tend to vent vapor in the heat (as does any tank, including a car’s), which is unpleasant when it’s in your frunk.

Finally, engines of all kinds really don’t like being left sitting for months on end unless prepared to do so. Generally you want to run them monthly, getting them up to operating temperature, putting a load on them for a bit to fully exercise all components.

I say all this because I have an EU2200i and dearly love it, but am also painfully aware of its limitations and needs. I got it when I lived in Texas because the power outages were getting to be absurd, and my house wasn’t plumbed for natural gas, so a whole-house was out of the question. The 2200i was plenty to power two fridges, a deep freezer, TV, fans, and my server rack. I got really good at quickly running extension cords (which is a whole other discussion on ensuring proper amperage ratings and calculating voltage drop, something most people ignore).

> The EU2200i can sustain 15 amps.

proverbial

I’ve ran mine at nearly that for hours without any issue. Honda generators do what they say they’ll do.

For a Honda 2.2kW to aid with range anxiety, you'd have to split range anxiety into two categories and I think it only addresses the second/lesser of the two.

Assume the car gets 4 miles per kWh delivered and the charging cycle is 90% efficient (measured from generator output). The 2.2kW generator can add 8 miles/hour of generator runtime (2.2 kW * 0.9 * 4 miles/kWh).

For range anxiety of the form "we're driving to a destination pretty far away and I'm not sure we can get there", that's not very helpful. For range anxiety of "I'm driving to a destination that's over half my range and then going to spend a full day [or overnight] there, but I'm not sure there will be working chargers available there", charging 8 mph times 8-10 hours is very helpful.

Worrying about being stuck in the boondocks without a charger is addressed by an 8 mph on-board charger, but I think that's the less common form of range anxiety.

The Chevy Volt range extender was 75kW; the i3's was 26.6kW. 2.2kW is literally an order of magnitude too small to replace those.

Posted something very similar above. It’s worse than 2200 watts: that’s the allowable overload draw, not sustained. After about 5 minutes, it warns you to reduce power to <= 1800 watts.

Also, something I didn’t mention in my post; at full power they’ll suck their tank dry in a little over 3 hours. You’ll get about 20 miles of range (using your assumptions above) from one. Tbf you can also parallel two of them, or buy a slightly larger model (EU3200i), but either way, it’s still not going to be anything other than an emergency backup where you have a lot of time to kill.

BMW tried that with the i3, it wasn't particularly popular. An engine, fuel system and a generator are all relatively complex additions compared to just putting the same cost and vehicle space into more batteries, and the public charging networks are definitely up to the task by now (having been EV-only for almost 5 years now).

I've ridden in one and this was basically a case of "you get the worst of both worlds". The engine was small and running at a constant RPM, leading to an annoying noise in the cabin. The range extension was not particularly huge. Worse, when we did eventually run out of battery on one trip, the range extender was unable to recharge the battery after refueling the car, forcing us to scramble to find an available charging station with the car on the tow truck...

I've been driving one for a while. On the trips I've driven, even on the highway, the engine was able to keep up with the energy draw. I think it's around 60HP. If I'm on a long trip, I'll start the engine once I reach 75% of my battery capacity. That gives a significant buffer for the engine. It's a serial hybrid.

Yes, the Volt was a better balanced version of that. It had a longer EV range and the range extender was larger. It was much less likely to need the range extender and when it did, the larger (1.4l) engine was no more noisy than any gas engine.

>> the range extender was unable to recharge the battery

Could you expand on this? What was the actual problem? For example, did the range extender start and run? Did it put any energy into the battery at all?

We ran out of battery and fuel (I was on the backseat so I don't remember the exact sequence, I just remember the car basically losing power without much warning on the autobahn). The car was towed to a gas station were we proceeded to refill the tank, but the range extender would not start and the car computer was adamant we had to recharge. Which led to a quest to find a public charger in the middle of the night, after 2 failed attempts, we gave up and asked to be towed to our destination instead since it was close enough.

The original BMW i3 had/has a lockout that prevented the range extender from charging the battery until it reached 6% in order to meet California's ZEV BEVx regulation.

facepalm

I don't know what to call this.

"Legislated fragility"

> An engine, fuel system and a generator are all relatively complex additions […]

And yet that's what an ICE car is.

So a range extender (RX) should be no worse than ICE: in fact a little less complex because you don't have a gear train and transmission.

The newer London black cabs do that

> The LEVC TX is powered by a full-electric hybrid drivetrain. It drives in full-electric mode all the time, but is recharged by an 81-horsepower (60 kW; 82 PS) Volvo-sourced 1.5-litre turbocharged three-cylinder petrol engine.

This does not make any sense. It's a cab, it's going to stay 100% of the time in a city or really near, moving around. If it ignites a petrol engine to recharge the battery, what's the point? Surely a cab driver can pause 20 minutes every 4 hours to go to the restroom and fast charge their EV, no?

Diesel REX vans would be a MASSIVE hit if a company would just decide to start making them.

The #1 reason for (european) companies not buying full EV vans is range, they need to drive a LOT during the day.

REX would solve that with minimal emissions. And depending on the battery size, they could drive on full EV in city centres and only allow the REX to charge the battery during longer drives.

The BMW i3 REX is a fantastic car, if you can find one, buy it.

They are the cheapest hybrid out there currently, at least here in the USA. I think the average American prefers a larger vehicle.

I think a Diesel indirect injection REX would be awesome. It could burn vegetable oil, which is more viscous, but indirect injection doesn't need to atomize the fuel as much.

Range anxiety seems to go away after your first week of EV driving.

I'd say more that it evolves rather than goes away. We've had our BEV for over a decade and it's the car we tend to choose to drive for short distance errands. We like it by all means, but when one of us needs to take the hybrid car for a weekend or a local business trip, we still have to plan out to make sure the other can manage whatever we need to do with just the BEV.

As dboreham says in the sibling comment, the range anxiety morphs into charger-availability anxiety. Even if I know a charger physically exists at my destination, if it's 45% or more of the range away, I still need to worry that it will be working, that my access will work, that it won't be occupied or blocked, etc.

In nearly 40 years of driving, I almost never researched gasoline availability (through the Nevada desert and in Central America, I did).

In a little over a decade of BEV driving, I've done a lot of EVSE (charger) researching.

It isn't really "range" anxiety, rather "no charger available" anxiety.

Today, if I run out of petrol|gasoline somewhere, even if I'm in the middle of nowhere and don't have a gas can, I can still recover from that situation within an hour or so (hitch a ride to the next gas station, buy gas can, fill with gas, hitch back to my vehicle). With an EV the density of fueling/charging locations is orders of magnitude lower than for gas, and if I end up discharged I'm looking at finding a flat bed truck, or perhaps a mobile high power generator.

Disclosure: I own both kinds of vehicles.

Eh, I'd say it goes away after your first road trip, unless you're going somewhere remote.

I've had my BEV for about 5 1/2 years. My first road trip (Portland -> Santa Clara, ~560 miles each way), I planned it out ahead of time with ABRP. These days, I'll just let the nav figure it out.

First time I did an EV road trip, I just plugged it straight into the car screen and followed directions. I didn't have anyone with me, and was willing to accept some degree of "adventure". I did about 800 miles in a day, and had zero real issues.

I have been totally unconcerned about it since.

One 120V 2.2kW generator isn’t going do much at all. It’s really actually 1.8kW which is 15A at 120V.

You’d need to tow around a 7.2kW 240V for 30A at 240V (more likely a 14.4kW generator for 240V 60A).

Using the small Honda inverter generator (which is amazing for plenty of stuff!) is akin to covering your car in solar panels to get range extension, the math just doesn’t work out.

Maybe because people don't want to have oil changes, emission checks, exhaust gas etc. on their EV. If they really need a long range, they will probably just buy a combustion engine car.

Perhaps, but other than the upcoming Scout, I’m not even sure it’s an option for EVs, in the US.

BMW i3 has/had a REX version and when I researched it people seemed to agree it’s the least reliable part about owning it. But that might be it!

Afaik that’s pure series hybrid and that’s almost non-existent in cars (outside of range extenders, not that there are that many of those).

There are a handful but most hybrids are either parallel or series-parallel. I assume because the power range is so low that the conversion losses are way too noticeable compared to a mechanical drivetrain.

No, the entire point of a series-parallel hybrid is that it can offer the advantage of a series hybrid.

The Toyota Prius powerchain has two motor generators, and can take part of the ICE power from one and transfer it electrically to the other, remapping the engine RPM into more efficient power bands at the same time. It has a mode that can do this even when no power is being used from the battery.

It’s kind of a best of both worlds. They can avoid the extra weight of a full series hybrid, because they don’t need a motor generator pair that handles the full engine power.

Actually, power bands remapping is essential for the Prius to operate.

There is no clutch, there is no neutral gear, there is no torque converter. The ICE is always connected directly to the wheels with a fixed gear ratio on a planetary gear set. (Which improves transmission efficiency over a automatic/CVT gearbox, and actually reduces maintenance costs)

One of the motor-generators is on the 3rd input of the planetary gear. For the ICE to idle (during warm up, or when you have the heater on), the motor-generator much be spinning backwards at the exact same speed so that the wheels stay stationary.

Power band remapping can also be used for reversing when the battery is empty.

Current Honda hybrids are like that. The only time the Internal Combustion Engine (ICE) is directly connected to the drive train is when the speed gets to above around 60MPH. The rest of the time the ICE is used to power a generator which then sends power to the electric motor and/or the battery pack.

https://www.youtube.com/watch?v=QLUIExAnNcE has more info.

That's something I wish there had been more focus on, instead of focusing on massive heavy batteries, develop the hybrids further.

Not sure about the US, but the Japanese didn't stop focusing on hybrid development. More than half of all sales in Japan are hybrids, whereas electric is only a few percent [1].

Honda even recently announced that they're scaling back on electric to focus on hybrids:

https://www.reuters.com/business/autos-transportation/japans...

[1] https://www.bloomberg.com/news/articles/2023-12-19/hybrid-ca...

Yes but Honda seems to be doing this because they can’t make batteries. BYD can, ever cheaper, and they’re expanding their plug-in offerings much faster than Honda is scaling them back. I’m worried for Japanese car makers.

Yep. Hybrids are a dead end, they’ll be obsolete in a few short years

But series-parallel has the very same advantage - can keep the RPM in sweet spot.

This is how diesel-electric locomotives work too.

They also use the electric motor(s) for braking, but instead of going into a battery it goes into a bank of resistors.

I think you meant capacitors. Resistors would just dissipate the energy as heat.

edit: Thanks for the correction. They do indeed use resistors and just dump the energy as heat. Unfortunate.

Hopefully this will change as supercaps continue to improve. Maxwell tech's modules are already used in light rail, and looks like some work towards smaller locomotives in Switzerland here:

https://www.osti.gov/etdeweb/servlets/purl/20823697

Capacitors have pitiful energy storage capacity. Resistors is correct, unfortunately.

Nope, resistors. The energy is dumped as heat.

Dynamic brake

To add to the other comments: https://en.wikipedia.org/wiki/Dynamic_braking

Most hybrids on the road are parallel and have a mechanical connection to wheels and vary rpm as needed, although the CVT implementations may hold rpm due to gear ratios like any CVT hybrid or not.

A direct mechanical connection is more efficient at highway cruise speeds than a mechanical->electric->mechanical conversion.

The main win a gasoline hybrid has is in running the Atkinson cycle gaining efficiency while losing torque which the electric motor makes up. This brings the gasoline engine up into diesel efficiency territory.

This is also why you don't really diesel hybrids, the engine is already very efficient but it is more expensive and heavier and hybrid adds more expense and weight.

Diesel engines with all their turbochargers, EGR, SCR, DPF etc equipment, work pretty well as part of a hybrid system. All that stuff works much better in steady-state operation. Diesel hybrid buses and trucks are much smoother and cleaner than non-hybrid.

There do exist serial hybrids where the engine produces electricity while maintaining the ideal RPM, and then is connected to a battery+electric motors.

However in practice the vast majority of hybrids do not use this approach and have motors that vary RPM with road speed (depending of gearing of course).

The common case of maintaining ideal RPM is the CVT, which most folks dislike, so much so that some models have a switch to pick how many fake gears you have to break up the boring drone of a constant RPM engine.

BTW, the chevy bolt was advertised as a serial hybrid, right up to the day it shipped.

I believe the most common serial hybrid today is an EV with a range extender.

I heard about that long ago but couldn't find more, so IIUC chemically it's easier and more efficient to have a "one mode" combustion engine and let the electric engine deal with the variations, to the point that the reaction produces near no toxic byproducts, is that right ? I was wondering if there was research to keep improving that part. Even though it would help sustain the fossil fuel industry..

Nissan hat the e-POWER system where a petrol engine is just used to recharge the battery of your electric car and nothing else. In theory they could run that petrol engine at the sweet spot where it produces the least amount of carbon emissions.

i believe there is also a chinese company which is making such a car, their cars have nearly 1000 miles range.

Diesel-electric engines in trains and tanks worked like that during WW2.

AFAIK this is about engine efficiency. ICEs have highest momentum and efficiency sweet spot somewhere in the middle of available revs, which depends on the engine construction and was being altered by different mechanisms (like turbocharging and variable valve timing) but since the electric engine (I'm speaking of Toyota solution) is able to keep the ICE in the sweet spot with its eCVT, the engine can be simplified and even work on different combustion cycle (Atkinson's cycle)

> ICEs have highest momentum and efficiency sweet spot somewhere in the middle of available revs

Close: they have the highest efficiency at about 90% of maximum torque for most of the RPM range. So if you want double the power, you want to be able to double the RPM; and if you want half the power, you want to be able to drop the RPMs in half. To pull this off, you either need a very quick shifting gearbox or some sort of CVT.

This is also why automatic transmissions, despite being ~80% efficient versus ~95% manual transmissions, are not much worse on mileage. Because they can quickly switch between low RPM and higher RPM (first by torque converter lockup, second by switching gears).

> a significant benefit from allowing the ICE to remain in the RPM "sweet spot" rather than moving around a larger range.

I remember buying plans from the Whole Earth News for such a car back around 1980. That was the selling point - keep the ICE running at an optimal point. I've not seen those same plans reproduced online.

Aha! https://store.motherearthnews.com/products/hybrid-car-bluepr...

In order to do this with a gas engine, it can be done but you need to completely mechanically decouple the gas engine from the drivetrain. The gas engine needs to do one thing and one thing only which is charge the battery. The gas engine has maximum efficiency at about 80% throttle.

The efficiency of the entire system is more important than the efficiency of the engine itself. Charging the battery and then discharging it also incurs losses. Many series hybrids will prioritize generating electricity when some of it is also required to directly drive the motor. They usually don't sit around at low-load situations just generating electricity, unless SOC is low.

> The gas engine has maximum efficiency at about 80% throttle.

ICE efficiency varies in multiple dimensions based on load and RPM, and in a series hybrid, you have some ability to dynamically influence these... throttle would be one of those inputs.

That's the case only with CVT transmission

Are there still a lot of hybrids without CVTs?

Hyundai/Kia use a traditional 6-speed auto in their hybrids. I drive one, the engine stays at a few RPM stepping points during most driving (it likes ~1600RPM, ~2200RPM, and ~3600RPM). I had a Prius previously, and I like this different setup because it reduces "engine droning noise", which was terrible on the Prius.

Though H/K have recently introduced a new hybrid system with a CVT, so maybe 2026 or 27 model years will be different.

Since I'm only making one comment, I also want to say hybrid cars are better than ICE because there are fewer belt-driven accessories. Aircon in particular on an electric motor is a big improvement. Without the idling engine producing heat, hybrids are much nicer in hot stop-and-go conditions!

Also my Prius made it its whole life (200k miles and ~20 years) without ever changing the brake pads... amazing!

I'd say that the market is very fragmented.

Toyota and Lexus, obviously, use eCVT in their cars.

Honda is also in eCVT camp for most of their models but for example new CR-V has weird setup. It acts as an BEV until ~80-100kmh and then shifts completely to ICE with a single gear. While in EV mode the engine is constantly charging batteries.

Then you have KIA and Hyundai with their dual clutch setup in all HEV and PHEV range.

Lots. BMW, Audi, Mercedes, Porsche, Volkswagen, Volvo for example.

I find it a pity that Lexus uses CVTs as I would probably sell my BMW 330e and get a Lexus.

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