PHEV's virtual electric overdrive.

[Trex]

Well one of the things that was mentioned is that at > 78 mph, the ICE runs continuously.

So that should not affect you too much as from memory when I drove around California on 2 different trips over there the highest speed limit I saw was 70 mph which is approx 110 kph which is the same as around here.

But I suppose that could have changed since I was there.

So lets say you are travelling around California on the highway at the legal speeds I can remember over there I think your petrol motor should be running approx at 1,950 RPM on average over time ie approx 2950 RPM that I see at 110 kph X the approx 66% of the time the petrol motor runs that I see at that speed gives 1,947 RPM. That's a virtual electric overdrive right there IMO.

Disclaimer: that is what I see at those speeds and the loads and the drive battery SOC I travel with on my PHEV. It may vary with yours.

Well...you're assuming everyone always obeys the speed limit.

:lol: :lol: Where the bloody hell did I say that? I have been around too long to assume anything. Something about making a ASS out U and ME. :twisted:

If you go out on I-5 and do the speed limit, people are going to flip you the bird.

I have been down to San Diego and up to San Francisco using I-5 at the legal speed limit (GPS) and no one flipped me the bird from memory. :idea: They might be scared of us Aussies. Or I couldn't have cared less if they did.

Will share some history STS134 about how all the young blokes that worked with me rat racing to get to the pub on a Friday afternoon after we picked up our wages. It was a big thing to get there first and get the first schooner of beer. Well we were beaten by this old guy that worked with us every time. So how did he do it? By leaving early ie he picked up his wage on Mondays. There is us racing and busting our gut to be first and this old guy casually drives there and wins every time. There is a lesson there for all of us IMO.

I am really starting to think you bought the wrong car STS134. Trying not to use the drive battery, wanting gears, bigger tank............

 

[AndyInOz]

I'm not sure about the over-revving concept.

My previous car used to do high speed cruising at 5,500 RPM. (It red-lined at 7,000 RPM).

Are you comparing the 2 litre PHEV with a 6 litre V8 or suchlike?

 

[STS134]

I'm not sure about the over-revving concept.

My previous car used to do high speed cruising at 5,500 RPM. (It red-lined at 7,000 RPM).

Are you comparing the 2 litre PHEV with a 6 litre V8 or suchlike?

Nope, 2018 Corolla, which my wife drives daily. And yes, it does really do 2400 RPM @ 90 mph at its lowest effective gear ratio (highest effective gear) when it doesn't need power for accelerating and passing. It's actually much better than the 2000 Corolla I replaced with the PHEV, which would be at around 3000+ RPM @ 90 mph with its 4 speed tranny (around 3100-3200 RPM if I remember correctly, even in its overdrive gear). When you want to accelerate, climb, or pass, it does rev up to over 4k RPM easily, but the CVT keeps the engine in its optimal RPM range for the instantaneous power being requested. The only time it'll do around 3400 RPM @ 90 mph when cruising is when I put it in "S" mode. Why couldn't Mitsubishi have put a CVT in between the clutch and the wheels? Would really help save the battery from wear when climbing (boost from motors when the ICE could just rev up, but can't due to fixed gear ratio is rather stupid) as well as when cruising (the topic of this thread). Are we really to believe that it's better to generate energy, push it into the battery, and then shut down the engine and draw from the battery at 2-3C (24-36 kW)? First of all, each round trip through the battery costs about 10-20% in energy, at least. That's not efficient. Then there are the power losses in the motors themselves when they convert mechanical energy to electrical or vice versa. It's always more efficient to just take mechanical energy and output...mechanical energy, if that's what you really want to do with the useful work.

Actually, the whole idea that you want to downsize the ICE and let the battery take up slack is a bit flawed. When climbing the Grapevine on I-5, I was monitoring both SoC and battery temperature, and I had had the vehicle in Charge mode nearly the entire drive since I had left home. Since the transmission has a fixed ratio, and since the ICE is undersized, the engine couldn't produce enough power to climb, and so required an assist from the motors...for 5+ miles, up a 6% grade. Ultimately, I drew about 6 bars (out of 16 bars) from the battery, despite the fact that there was a small traffic jam on the way up (a car had crashed). If not for the crash, I would probably have used 8 to 10 bars or around 50% of the capacity on the battery meter, and around 30-40% SoC overall. By the time I got to Tejon Pass, my battery temperature was around 25°C for the coolest cell and 34°C for the warmest! It was a very cold day, and the battery temperatures were hovering around 11°C to 17°C when I started the climb. Drawing power from the battery at that rate (around 3-4C or 36-48kW by my calculations) is not efficient at all, and in fact is very detrimental to the lifespan of the batteries.

 

[anko]

[Conclusion: this car that is hopefully designed with the environment in mind is not optimised for high speed driving?

Well, I think even with a basic 3 speed tranny between the clutch and the wheels, it would do a lot better. At least it could keep the engine at lower revs for cruising and higher revs for climbing.

It already does that: When cruising in parallel mode and power demand is low, revs are lower. When power demand is high, revs are higher. Sure, at high speed there is not much of a difference anymore. But like I said, high speed cruising is probable not what they had in mind. The Vmax of 170 km/h could have been an indication ....

 

[STS134]

It already does that: When cruising in parallel mode and power demand is low, revs are lower. When power demand is high, revs are higher. Sure, at high speed there is not much of a difference anymore.

You mean series mode right? I.e. engine turns generator, motors turn wheels, and the only connection between the engine and the wheels is through electricity. In parallel mode (clutch engaged), the system is effectively a direct drive system, and engine RPM and wheels are at a fixed ratio, which is the whole crux of this issue.

But like I said, high speed cruising is probable not what they had in mind. The Vmax of 170 km/h could have been an indication ....

Shrug. Most economy cars weren't designed with high speed cruising in mind either. My previous car had a Vmax of around 180-190 km/h (not due to any limiter, mind you, but simply due to physics). Because the speedometer only went up to around 180 km/h, I had to verify the Vmax with GPS. But it did a lot better at keeping its ICE at a decent RPM for the driving demands. And the new economy cars with CVTs are even better at that task.

 

[VillageIdiotDan]

the speedometer only went up to around 180 km/h...

Slightly off track and more than slightly naive of me but I thought all US drivers obeyed the speed limit religiously and often the speed limit was something pathetic like 55mph. I honestly had no idea that you guys hit those sort of speeds!!!

 

[STS134]

Slightly off track and more than slightly naive of me but I thought all US drivers obeyed the speed limit religiously and often the speed limit was something pathetic like 55mph. I honestly had no idea that you guys hit those sort of speeds!!!

I wouldn't do this in an urban area except maybe very late at night when there's almost no traffic, but what would you do in an area like this? The conditions depicted in the street view here are typical:
https://www.google.com/maps/@35.5554571,-119.5954779,3a,75y,128.53h,92.94t/data=!3m7!1e1!3m5!1syQRMO07xEUjYuggw3ZHjPw!2e0!6s%2F%2Fgeo3.ggpht.com%2Fcbk%3Fpanoid%3DyQRMO07xEUjYuggw3ZHjPw%26output%3Dthumbnail%26cb_client%3Dmaps_sv.tactile.gps%26thumb%3D2%26w%3D203%26h%3D100%26yaw%3D227.8076%26pitch%3D0%26thumbfov%3D100!7i13312!8i6656

Sometimes, you get out here and you just go as fast as you can, because you can see 10 miles, there's almost no traffic, and it's boring as hell.

 

[Trex]

Why couldn't Mitsubishi have put a CVT in between the clutch and the wheels?

Well you "seem" to be smarter than Mitsi so why don't you apply for a job with them? You could redesign the PHEV to suit yourself. But sorry, I will not be buying your design. Had 2 Toyota hybrids with what they describe as a eCVT from memory. Screaming ICE climbing hills that the PHEV now climbs silently.

Would really help save the battery from wear when climbing (boost from motors when the ICE could just rev up, but can't due to fixed gear ratio is rather stupid)

Stupid. WOW. . Now you are trolling IMO but I will bite. :roll: So no "in my opinion" or "I think" just a broad statement that shows how smart you "think" you are. Yep, smarter than any old crappy Mitsubishi engineers. :lol: :lol: Well I think that if you are not purposely trolling you are, to put as nicely as I can, acting like a smart arse IMHO.

Are we really to believe that it's better to generate energy, push it into the battery, and then shut down the engine and draw from the battery at 2-3C (24-36 kW)? First of all, each round trip through the battery costs about 10-20% in energy, at least. That's not efficient. Then there are the power losses in the motors themselves when they convert mechanical energy to electrical or vice versa. It's always more efficient to just take mechanical energy and output...mechanical energy, if that's what you really want to do with the useful work.

Now I was going to help explain why Toyota and Mitsubishi try and shut down that bloody inefficient ICE as much as possible but as I now think you are trolling or acting like smart arse I will not bother. Oh ok, just because I am in a good mood I will give you a hint. Look up how efficient an ICE is and have a look at our effective overdrive ratio (which is what this thread is about) when the PHEV is driven sensibly to IMO how it was designed.

......... (a car had crashed). If not for the crash..............

Yea, I think it probably was some idiot that was breaking the speed limit and lost control. Happens over here sometimes. Matter of fact been to funerals from that cause. Hard to watch those little coffins of the kids killed in the accident. Did not care too much for the driver that caused it in those circumstances.

 

[STS134]

Why couldn't Mitsubishi have put a CVT in between the clutch and the wheels?

Well you "seem" to be smarter than Mitsi so why don't you apply for a job with them? You could redesign the PHEV to suit yourself. But sorry, I will not be buying your design. Had 2 Toyota hybrids with what they describe as a eCVT from memory. Screaming ICE climbing hills that the PHEV now climbs silently.

eCVTs are horrible. I was referring to a full, traditional, mechanical tranny, none of that eCVT silliness that's in the Toyota HSD system. The HSD eCVT can literally only do ONE ratio without an electrical path, as MG1 and MG2 must both be running to vary the ratio, which means power losses. Extreme power losses that apparently get worse as total power level increases. I've heard that when you get above around 100 HP, they start pushing up and over 25% transmission losses, which is absolutely crazy, so basically on everything that's not a Prius, it's inefficient as hell. It's probably a combination of the larger amounts of power being shunted between MG1 and MG2, and the beefier gears that you need to take the extra power, and in any case, explains why this system has not been more widely adopted in other cars.

Ideal system looks like this (ignore the dots, they were needed as "filler" to make this diagram display properly):

Generator <-----> ICE <------> Clutch <-------> Full mechanical transmission <---------> Motors <----------> Wheels
|.......................................................................................................................................^
|.......................................................................................................................................|
----------------------------------------------------> Battery <------------------------------------------------

1. Driving with battery charge: Generator can generate energy to charge the battery while the ICE also powers the vehicle with the clutch engaged.
2. Charging battery while stopped: Generator can generate energy to charge the battery with the clutch disengaged when the vehicle is stopped
3. Series mode: Clutch is disengaged. ICE powers generator, which powers motors.
4. ICE-only mode: Clutch engages, and the full mechanical transmission is used to keep the ICE in its optimal RPM. Ideally, the motors would be locked when cruising, so that all ICE power is transmitted to the wheels directly. Generator freewheels.
5. Full EV mode: Motors power the wheels in what's basically a direct drive mode, discharging the battery and moving the car.
6. Series-Parallel mode: ICE powers both generator AND transmission with clutch engaged. Generator power is shunted to motors, which also power the vehicle and add to the output of the transmission.
7. Regenerative braking: Motors act as generators, and charge the batteries.
8. Engine braking: If the battery is fully charged, lock the motors and put the mechanical transmission into a low gear, forcing the ICE to turn with the throttle closed and safely dissipating energy as heat into the ICE and out the cooling system.
9. "Boost" mode: ICE powers wheels through transmission. Generator freewheels. Motors add to ICE power by drawing from battery.

Note that if more power is desired, we can get it many different ways: (1) By "boosting" using the battery to turn the motors, with the ICE running and the transmission engaged; (2) By downshifting the mechanical transmission, which revs up the ICE and allows it to do more revolutions and do more work; (3) By running the generator and shunting power through the battery to the motors, if the battery is fully discharged, although I'm not sure why you'd want to do this given that you can just vary the gear ratio in the transmission and lock the motors.

This system is essentially the same as the GKN Multimode eTransmission, except it has a full mechanical tranny between the clutch and the wheels. That's literally the ONLY change I've made. And that one change enables (4), (6), and (8), the last of which is a HUGE improvement in safety. In theory, the GKN could probably do (6) but I have never seen it do it. Mode (4) is extremely useful for high speed cruising. Mode (9), which the GKN likes to do a lot while climbing hills or accelerating quickly from say 50 mph with the clutch engaged, is now no longer necessary unless the driver absolutely floors it.

 

[jaapv]

Why couldn't Mitsubishi have put a CVT in between the clutch and the wheels?

Well you "seem" to be smarter than Mitsi so why don't you apply for a job with them? You could redesign the PHEV to suit yourself. But sorry, I will not be buying your design. Had 2 Toyota hybrids with what they describe as a eCVT from memory. Screaming ICE climbing hills that the PHEV now climbs silently.

Would really help save the battery from wear when climbing (boost from motors when the ICE could just rev up, but can't due to fixed gear ratio is rather stupid)

Stupid. WOW. . Now you are trolling IMO but I will bite. :roll: So no "in my opinion" or "I think" just a broad statement that shows how smart you "think" you are. Yep, smarter than any old crappy Mitsubishi engineers. :lol: :lol: Well I think that if you are not purposely trolling you are, to put as nicely as I can, acting like a smart arse IMHO.

Are we really to believe that it's better to generate energy, push it into the battery, and then shut down the engine and draw from the battery at 2-3C (24-36 kW)? First of all, each round trip through the battery costs about 10-20% in energy, at least. That's not efficient. Then there are the power losses in the motors themselves when they convert mechanical energy to electrical or vice versa. It's always more efficient to just take mechanical energy and output...mechanical energy, if that's what you really want to do with the useful work.

Now I was going to help explain why Toyota and Mitsubishi try and shut down that bloody inefficient ICE as much as possible but as I now think you are trolling or acting like smart arse I will not bother. Oh ok, just because I am in a good mood I will give you a hint. Look up how efficient an ICE is and have a look at our effective overdrive ratio (which is what this thread is about) when the PHEV is driven sensibly to IMO how it was designed.

......... (a car had crashed). If not for the crash..............

Yea, I think it probably was some idiot that was breaking the speed limit and lost control. Happens over here sometimes. Matter of fact been to funerals from that cause. Hard to watch those little coffins of the kids killed in the accident. Did not care too much for the driver that caused it in those circumstances.

Some general Internet Forum advice: don't feed trolls. They thrive on attention and responses. Ignore them and they'll starve and crawl back into their burrow.

 

[STS134]

Now I was going to help explain why Toyota and Mitsubishi try and shut down that bloody inefficient ICE as much as possible but as I now think you are trolling or acting like smart arse I will not bother. Oh ok, just because I am in a good mood I will give you a hint. Look up how efficient an ICE is and have a look at our effective overdrive ratio (which is what this thread is about) when the PHEV is driven sensibly to IMO how it was designed.

The ICE should be at as low an RPM as possible, without lugging it, for the best fuel economy. Let me say that again: the ICE should be at as low an RPM as possible, without lugging it, for the best fuel economy. Engineering explained did an entire video dedicated to this topic.

https://www.youtube.com/watch?v=iNspNdVkslA

Now what the "virtual electric overdrive" does, is increase load on the engine (by charging the battery). Does this increase efficiency? Yes, of course. It puts the engine into a region of better brake specific fuel consumption. But it comes at two costs: battery replacement, and the fact that a roundtrip through the battery tends to lose energy (you don't get as much energy out of a battery as you put into it, as some is lost as heat). By pushing power into the battery and then drawing it out, and doing this repeatedly, again and again, when we're just cruising down the highway, it puts the battery through extra cycles that it shouldn't have to go through at all. And judging by all of the posts in the battery degradation thread, this seems to be an issue, doesn't it? It's far better to just lower the RPM on the engine and increase load by varying the gear ratio, i.e. by using a mechanical transmission.

Yea, I think it probably was some idiot that was breaking the speed limit and lost control. Happens over here sometimes. Matter of fact been to funerals from that cause. Hard to watch those little coffins of the kids killed in the accident. Did not care too much for the driver that caused it in those circumstances.

Now you are trolling. There's a difference between driving fast and driving like an idiot. I've driven probably 300k miles in my life and never hit anyone or anything else. Most of the idiots you see driving around do stupid maneuvers like weave in and out of traffic. High speed has nothing to do with why they get into crashes. It's deviation from prevailing speed that's the most dangerous, which means, if everyone else is doing 90 mph, you should be doing about 90. https://en.wikipedia.org/wiki/Solomon_curve Basically, don't pass people or allow other people to pass you at a high differential speed. It's also dangerous to have no lane discipline.

https://www.youtube.com/watch?v=4oqfodY2Lz0

 

[jaapv]

Don't allow people to pass you? That kind of road-hogging is a major cause of high-speed crashes. I would hate to see you drive on real motorways like the German Autobahn.

BTW, exceeding the speed limit by 20 mph will cost you over 300 Euro over here
By more than 30 mph you driving license will be revoked on the spot, if you drive double the maximum speed your vehicle will be impounded and the court will decide whether it will be returned... or not.

 

[greendwarf]

I've said this before and I know others don't agree but IMHO the PHEV is primarily a city car with the flexibility to enable it to be used on longer more rigorous "weekends". That is how I use it and it does the job perfectly.

Even if you don't agree with me, it seems rather unkind to blame Mitsu for designing a car that is not ideal for breaking the law. :roll:

NB. The Japanese are notoriously law abiding.

 

[STS134]

Don't allow people to pass you? That kind of road-hogging is a major cause of high-speed crashes. I would hate to see you drive on real motorways like the German Autobahn.

You shouldn't be blowing by people at a 30 mph speed differential is all I'm saying. If one person is going to blow by me at a 50 mph differential, there's not a whole lot I can do about it. But if EVERYONE is passing me at a 20 mph speed differential, it means I probably want to speed up. If there is traffic around, and you are significant above, or below, the prevailing flow of traffic, you should adjust your speed to be close to the prevailing speed. I try to keep differential speeds when passing to 15 mph or so, or less. And you certainly shouldn't be hogging the left lane and forcing people to pass you on the right. Do that in Germany and you'll get extremely angry drivers behind you who of course won't pass you on the right because it's illegal there and punishable with a fine. Americans seem to have zero lane discipline in this regard and it drives me nuts.

I've said this before and I know others don't agree but IMHO the PHEV is primarily a city car with the flexibility to enable it to be used on longer more rigorous "weekends". That is how I use it and it does the job perfectly.

Even if you don't agree with me, it seems rather unkind to blame Mitsu for designing a car that is not ideal for breaking the law. :roll:

NB. The Japanese are notoriously law abiding.

Well the other issue (related to the virtual electric overdrive) is that it can't climb at low speeds very well using its ICE when it's in parallel mode. I have no idea why the GKN doesn't just switch to series mode in this scenario, but many times it does not, and prefers to keep the clutch engaged and draw from the batteries for boost. The real issue though is that neither series mode NOR parallel mode with motor boost should be required at all. The ICE has plenty of power to climb on a purely mechanical path, with no electricity involved, if only the thing had a real gearbox.

Say you're coming up this hill, doing 50 mph (which is the posted speed limit). https://www.google.com/maps/@37.1616985,-121.9897161,3a,75y,92.12h,93.54t/data=!3m6!1e1!3m4!1sfgZ9yCU9mvLl4YyvL6yPrA!2e0!7i16384!8i8192 The GKN often keeps the clutch engaged, with the engine at around 2000 RPM, and of course being a rather steep grade, it can't generate enough power to climb. So it decides to rapidly draw power from the battery instead of switching to series mode a lot of the time (and I can't really figure out why) and of course it doesn't even have the option of doing what every single one of my other cars do, which is change the gear ratio and put the engine at 2500-4000 RPM to create enough power to climb.

This car would be so much better with a mechanical transmission. I suspect that the reason it doesn't have one is that the bean counters at Mitsu decided that they would rather save on costs for the initial sale, and thereby make the car cheaper to purchase, at the expense of two things: battery life and fuel costs in the future. As far as they're concerned, they don't care what happens after they sell you the car and get the money, because those extra maintenance and fuel costs are on you, not on them. The extra fuel costs for keeping the engine at 3700 RPM when doing high speed cruising though, they're not paying for regardless of what happens to the ICE or the batteries. As for the other item, we'll see what happens. They may pay for part of this anyway, in the form of warranty battery replacements.

 

[anko]

You are wrong. Total power output is 149 kW (2.0 ltr version). Only 89 of these come from the ICE. No amount of gears is going to change that.

Please sell your car.

 

[STS134]

I am well aware of the power limits of both ICE and motors. But I have seen battery boost come on at relatively modest total power outputs of around 50-70 kW (which are easy to figure out because they provide a power gauge). The reason is obvious: the ICE is incapable of producing those power levels at its fixed RPM.

 

[anko]

I am well aware of the power limits of both ICE and motors. But I have seen battery boost come on at relatively modest total power outputs of around 50-70 kW (which are easy to figure out because they provide a power gauge). The reason is obvious: the ICE is incapable of producing those power levels at its fixed RPM.

Well, that is the car you bought. Too bad you didn't investigate on your test drive. As a workaround, you could floor it, forcing it into series hybrid mode. Have fun with the noise associated with it. Same noise as a CVT will give you.

 

[STS134]

I am well aware of the power limits of both ICE and motors. But I have seen battery boost come on at relatively modest total power outputs of around 50-70 kW (which are easy to figure out because they provide a power gauge). The reason is obvious: the ICE is incapable of producing those power levels at its fixed RPM.

Well, that is the car you bought. Too bad you didn't investigate on your test drive. As a workaround, you could floor it, forcing it into series hybrid mode. Have fun with the noise associated with it. Same noise as a CVT will give you.

It's really too bad that no dealership would let me take a 300+ mile test drive with this thing. Anyone know what the thresholds are for causing the car to switch to series mode from parallel mode? I really think this is something that could be fixed with an ECU update...or with a user selectable option of some sort. Do you wish to have low noise, or do you wish to save your batteries and use the ICE to climb?

 

[jaapv]

Well, the answer to that is simple: no test drive no sale.
If you gamble you can lose. In your case you lost: you bought the wrong car. Just sell it and buy the right one. I can assure you that no factory in the world is going to change the basic design of their product for the convenience of one customer.

Strangely enough, when climbing, no conventional car gives me a choice. I have to shift down and accept engine revs. Actually climbing is the only time that the PHEV sounds like any other car.

 

[Tai626]

Probably a little bit of my background so we could understand a little bit more about California driving culture.

In 2001, I was transplanted in California from Brazil (Sao Paulo). Three day after I got the California license and my manly Ute, I was showing off my landlord how we drive in Brazil and passed a stop sign sliding. Of course the police was waiting in my blind spot and I got my first of only two traffic tickets up to date. I had to go to traffic school and sit for 8 hrs to relearn. The one of first thing the instructor said to us was the California speed limit culture: 10 mph above the sign, believe or not!

I am civil engineer by trade and have been trained to designing roads. The 70mph sign is usually design for the not so good condition (rain, wear out tires, etc..). So the California road is really acceptable to drive 10mph faster. Probably is why the people do it and CHP (California Highway Patrol) would “allowed” it.

Tai