Do not be scared of using that charge button.

[greendwarf]

I guess they must be selling two types of PHEV :shock: . In parallel mode, only changes in speed, which are mostly gradually, result in (linear) ch anges in RPM. Yes, like a normal car as long as you do not change gears. Altogether, in parallel mode RPM is quite steady. In serial mode however, any change in throttle position and / or any change in driving conditions (wind, incline, ...) result in a changes in RPMs. This results in what people call the CVT effect or the race conditions that so many people hate. I believe this is the main reason why many people use Charge or Save on te motorway: it allows them to stay away from serial mode. You said something similar yourself:

No not two different types of PHEV - 2 different types of driving conditions. :lol: There are not many higher speed roads in England where you can drive in parallel with a steady RPM (i.e. constant speed) for very long - varying speed limits, traffic jams, road works, inconsiderate drivers etc. etc. - and rarely "gradual"

However, in serial mode why would RPM change be linked to throttle position during normal driving? I thought the "screaming" complaints arose when needing power under heavy demand e.g. towing or up steep inclines. Are you suggesting the car tries to maintain SoC by increasing the revs to match drain on the battery?

 

[HPM1111]

Yes greendwarf that is what occurs when the revs go up in series mode, the battery is limited to 60kw total power so the generator (in tandem with the ICE) needs to make up the difference.
Is there any way we could avoid in motion charging (generator) charging? Say you have 80% charge and you will be doing 60 miles at 50 mph and you will do further 20 miles in town traffic?
In "normal mode" the car will drain the battery in say 20 miles and cycle the ICE for the remainder of the trip, that or you'll use CHARGE or SAVE (doing worse mpg) and it will keep a certain % for the final 20 miles.

 

[HPM1111]

In the above circumstances I would much prefer to drive all the 60 miles @50mph in parallel mode (at an RPM the ICE should economical enough) and have the exact 80% for the final 20miles in town. Anyway we could "force" this behaviour?

 

[HPM1111]

Looking online I found "ev box tunning phev" this seems to be the answer for part of my wishes, totally disabling ICE under 130km h (and therefore series hybrid mode) when ECO is selected. If it also allowed parallel mode to start when you wish (regardless of SOC) it would be perfect. Any thoughts on this device?

 

[anko]

However, in serial mode why would RPM change be linked to throttle position during normal driving? I thought the "screaming" complaints arose when needing power under heavy demand e.g. towing or up steep inclines. Are you suggesting the car tries to maintain SoC by increasing the revs to match drain on the battery?

It tries more than than match drain on the battery. When the car is in Serial mode, you are either in:
- using Charge mode at low speed
- using Save mode and in the engine-on part of the hysteresis cycle
- running around with low SOC at low speed (basically this the same as the one above, but this time the car has selected the low water mark)
- pushing it so hard at higher speed that you need more than the 60 kW available from the battery + what the ICE can provide in parallel mode
- pushing it so hard at higher speed that you need more than what the ICE can provide in parallel mode, with very, very low SOC (this is what happens during towing a big caravan)
- pushing it so hard at lower speed that you need more than the 60 kW available from the battery

In the last three situations, I think it is pretty clear there is not much relation between speed and RPM ;-)
In the other situations, the electrical power from the ICE will be used to propel the car and charge the battery where possible. So yes, any change in throttle position or driving demand has an impact on RPM. Not just changes in speed.

Under normal conditions, Save mode does not really exist on it's own. You are always in a hysteresis cycle: engine on (drive car + charge battery) -> engine off -> engine on ....

The only exception (that I know of) is when you have less then 5 litres of petrol in the tank. Then the ICE will make no more effort than is needed to just drive the car (or heat the cabin).

 

[anko]

Yes greendwarf that is what occurs when the revs go up in series mode, the battery is limited to 60kw total power so the generator (in tandem with the ICE) needs to make up the difference.

One the ICE needs to kick in, it will be the other way around: the ICE will do most of the work and the battery will support it, if needed. In parallel mode, the ICE will be restricted in terms of RPM and thus power, and the battery will have to do more work.

Is there any way we could avoid in motion charging (generator) charging?

In the above circumstances I would much prefer to drive all the 60 miles @50mph in parallel mode (at an RPM the ICE should economical enough) and have the exact 80% for the final 20miles in town. Anyway we could "force" this behaviour?

You have not much trust in the efficiency of the drive train, do you? :mrgreen: The idea of the hysteresis cycle is that the average load of the ICE, when running, is higher but the ICE will be running less. Despite conversion losses, this should increase overal efficiency. Just think about the total number of revolutions your ICE will make .... If running around in a true Save mode (engine propels car, but does not charge battery) would be more efficient, would Mitsubishi have bothered implementing a hysteresis cycle? They drop the hysteresis cycle only at speeds above approx 125 km/h. And this is because EV mode is no longer possible. I would say, use Save mode if you must, but don't worry about it not being true Save mode.

In "normal mode" the car will drain the battery in say 20 miles and cycle the ICE for the remainder of the trip, that or you'll use CHARGE or SAVE (doing worse mpg) and it will keep a certain % for the final 20 miles.

Rather than using Save mode from the beginning, I would suggest you allow the battery to drain quite a bit and regain needed SOC towards then end of the high speed part of your trip. By keeping SOC at 80%, you limit charge current and thus cripple the car's hysteresis cycle (effectively, you are getting close to the "parallel mode with no charging, you seem to be looking for). You think it may increase efficiency. Some don't believe it makes a difference (or not enough to worry about it). Some others have made an effort to test this and came up with positive proof that there is some efficiency gain by allowing SOC to drop.

 

[anko]

Looking online I found "ev box tunning phev" this seems to be the answer for part of my wishes, totally disabling ICE under 130km h (and therefore series hybrid mode) when ECO is selected. If it also allowed parallel mode to start when you wish (regardless of SOC) it would be perfect. Any thoughts on this device?

It does not totally disable ICE under 130 km/h. Yes, it is possible to drive (almost) 130 km/h, without ICE, but this is also possible without the box. 'All' it does is dampen you throttle input so that unintentional ICE start up (caused by deep or fast depressing of the throttle) is prevented. Which is great! But it does not do what you seem to be looking for. But like I said, I think you should trust the hysteresis cycle to be more efficient than a true Save mode (parallel drive without charging)

 

[jaapv]

The reason people seem to hate the high-revving engine has nothing to do with efficiency or even the sound itself. After all, there are many cases that a normal car will rev up to maximum revs, and people seem to love screaming through the gears at traffic light sprints, or blasting up a hill in low gear, especially with a loud exhaust.

The problem is a Pavlov-induced disconnect.
We are conditioned to associated the engine sound with road speed and gear chosen, however, on the PHEV the engine sound is associated with power delivered only.

The conditioned mind registers this as "something wrong" Drive the PHEV for a period of time and your brain will be deprogrammed and annoyance will disappear, at least for most people. It depends on the flexibility of your subconscious.

 

[ThudnBlundr]

jaapv - that's the reason I disliked driving Toyota hybrids. The throttle does control the engine speed, but only vaguely. When you accelerate a Toyota, you never know if you'll get electric-alone, electric-plus-peak-torque or electric-plus-peak-power. Knowing that the PHEV ICE is only a generator most of the time seems more logical, though the smell after climbing a steep hill was worrying :shock:

Mind you, the disconnect is also there in electric-only mode. SWMBO got her first ever speeding ticket as she was unaware of the gradual acceleration on a 30mph road due to lack of engine noise feedback

 

[anko]

The conditioned mind registers this as "something wrong" Drive the PHEV for a period of time and your brain will be deprogrammed and annoyance will disappear, at least for most people. It depends on the flexibility of your subconscious.

For many situations, I agree. Like speeding up on an on-ramp. But, after several 1000s of kms of towing my caravan while my car switches between parallel mode (2600 RPM) and serial mode (4000 RPM) every 2 or 3 km, I must cone to the conclusion my subconscious is not very flexible :mrgreen:

 

[maby]

The reason people seem to hate the high-revving engine has nothing to do with efficiency or even the sound itself. After all, there are many cases that a normal car will rev up to maximum revs, and people seem to love screaming through the gears at traffic light sprints, or blasting up a hill in low gear, especially with a loud exhaust.

The problem is a Pavlov-induced disconnect.
We are conditioned to associated the engine sound with road speed and gear chosen, however, on the PHEV the engine sound is associated with power delivered only.

The conditioned mind registers this as "something wrong" Drive the PHEV for a period of time and your brain will be deprogrammed and annoyance will disappear, at least for most people. It depends on the flexibility of your subconscious.

I just want to minimise wear and tear on my car! For me the primary reason for buying a hybrid (apart from the tax concessions) is mechanical simplicity - virtually no gearbox, virtually no clutch, and an engine that is ticking over most of the time. I prefer the idea of the Toyota drive train with the petrol engine and electric motor both able to drive the car at all speeds and cooperating to maximise fuel efficiency, but unfortunately the tax rules have changed now and there is no financial incentive to buy Toyota hybrids.

 

[anko]

For me the primary reason for buying a hybrid (apart from the tax concessions) is mechanical simplicity - virtually no gearbox, virtually no clutch, and an engine that is ticking over most of the time.

I prefer the idea of the Toyota drive train with the petrol engine and electric motor both able to drive the car at all speeds

You want to have virtually no gearbox, yet you prefer an ICE capable of driving the car at all speeds. I don't see how these go together. I mean, compared to a conventional car, yes. But compared to the PHEV?

 

[jaapv]

The reason people seem to hate the high-revving engine has nothing to do with efficiency or even the sound itself. After all, there are many cases that a normal car will rev up to maximum revs, and people seem to love screaming through the gears at traffic light sprints, or blasting up a hill in low gear, especially with a loud exhaust.

The problem is a Pavlov-induced disconnect.
We are conditioned to associated the engine sound with road speed and gear chosen, however, on the PHEV the engine sound is associated with power delivered only.

The conditioned mind registers this as "something wrong" Drive the PHEV for a period of time and your brain will be deprogrammed and annoyance will disappear, at least for most people. It depends on the flexibility of your subconscious.

I just want to minimise wear and tear on my car! For me the primary reason for buying a hybrid (apart from the tax concessions) is mechanical simplicity - virtually no gearbox, virtually no clutch, and an engine that is ticking over most of the time. I prefer the idea of the Toyota drive train with the petrol engine and electric motor both able to drive the car at all speeds and cooperating to maximise fuel efficiency, but unfortunately the tax rules have changed now and there is no financial incentive to buy Toyota hybrids.

Well, for a car built to last for over 300.000 km wear and tear is not a very strong argument.

 

[jaapv]

For me the primary reason for buying a hybrid (apart from the tax concessions) is mechanical simplicity - virtually no gearbox, virtually no clutch, and an engine that is ticking over most of the time.

I prefer the idea of the Toyota drive train with the petrol engine and electric motor both able to drive the car at all speeds

You want to have virtually no gearbox, yet you prefer an ICE capable of driving the car at all speeds. I don't see how these go together. I mean, compared to a conventional car, yes. But compared to the PHEV?

Quite simple. Use a steam engine.

 

[HPM1111]

But like I said, I think you should trust the hysteresis cycle to be more efficient than a true Save mode (parallel drive without charging)

Perhaps I should trust it (and I will), if I am doubtful of the system´s efficiency it's due to all the reports of low 30's mpg on the motorway without towing. A big suv is never going to be the ideal motorway car due to less than perfect aerodynamics but if you look at it it´s also not the obvious city car , yet being a hybrid "all in one" and one of the few ev/phev that is both spacious and able to tow it will most definitely be used for towing carvans and do lots of long journeys.
I'm unsure mitsubishi used hysterisis cycle for true mpg/emissions reduction but rather to ensure long battery life with a small battery pack and relatively high eletric motor power output (along with eletric 4wd)

 

[maby]

For me the primary reason for buying a hybrid (apart from the tax concessions) is mechanical simplicity - virtually no gearbox, virtually no clutch, and an engine that is ticking over most of the time.

I prefer the idea of the Toyota drive train with the petrol engine and electric motor both able to drive the car at all speeds

You want to have virtually no gearbox, yet you prefer an ICE capable of driving the car at all speeds. I don't see how these go together. I mean, compared to a conventional car, yes. But compared to the PHEV?

The Toyota drive train has no gearbox and the ICE drives the wheels directly at all speeds. Power is supplied to the wheels from both the ICE and the electric motor via a three way differential with a fixed ratio and the gears in permanent mesh. The gear ratio of that differential is equivalent to top gear on a conventional car such that the car cruises at motorway speeds with the ICE running at moderate speed and little input from the electric motor. At lower road speeds, this would leave the car unable to accelerate - the combination of the battery and electric motor provide the additional power for acceleration.

 

[anko]

The Toyota drive train has no gearbox and the ICE drives the wheels directly at all speeds. Power is supplied to the wheels from both the ICE and the electric motor via a three way differential with a fixed ratio and the gears in permanent mesh.

Fixed ratio or not, a box with gears is a gearbox, isn't it? Like I said, far less complicated than the one in a conventional car, but still more complicated than the one in a PHEV

 

[jaapv]

As far as I am aware, the Prius has a CVT and planetary gear. That is a variable gear train, AKA gearbox.

 

[maby]

As far as I am aware, the Prius has a CVT and planetary gear. That is a variable gear train, AKA gearbox.

it does not have anything that I would describe as a gearbox - and I understand the Toyota drive train very well. The petrol engine and electric motor couple into two ports of a three port differential and the third port is coupled to the input port of a second three port differential with the wheels on the other two ports. The CVT effect is achieved by adjusting the speeds of the petrol engine and the electric motor. This latter can also function as a generator so if you are asking for a low road speed with a state of charge that is too low to deliver it from the battery, then the engine can run at a comfortable speed - a couple of thousand RPM - and the speed at the road wheels can be controlled by adjusting the load presented by the motor functioning as a generator. If there is sufficient charge in the battery to meet the demand through the electric motor, then the petrol engine is stopped, locking the corresponding input shaft to the first differential and the electric motor is coupled to the wheels via the fixed ratio of the differential.

There is a second motor-generator which is physically attached to the output shaft of the petrol engine. This is the primary electrical generator for the car and is what is usually responsible for recharging the battery. It also functions as the starter motor for the engine. Unlike the PHEV, the Toyota engine in its hybrid ranges can be fully decompressed when it is stopped, so the required power to start it is pretty low. The motor-generator that is coupled to the first differential is primarily used as a motor, but can be run in reverse as a generator - this is the one that is responsible for regenerative braking.

This arrangement gives the control systems a lot more flexibility in the control of power flow. There is a mode of operation in which the petrol engine is both driving the wheels directly and generating electricity via the generator on its output shaft and that electricity is producing power which is going to the wheels via the second motor-generator. There is a second mode of operation which kicks in when you are running at a low road speed on a flat battery in which the petrol engine is driving the road wheels directly and excess output is being bled off via the second motor-generator and put back into the battery bank.

The mechanical ratio of the planetary differential is fixed and there is no equivalent of the variable ratio that is implemented in more conventional CVT transmissions using cones, belts etc.

 

[anko]

As far as I am aware, the Prius has a CVT and planetary gear. That is a variable gear train, AKA gearbox.

it does not have anything that I would describe as a gearbox...

Toyota would .... (http://blog.toyota.co.uk/how-does-toyota-hybrid-synergy-drive-work):

Toyota’s Hybrid Synergy Drive system is comprised of six primary components: a petrol engine, an electric motor, an electric generator, the power control unit, and a power split device that uses a special type of gearbox to smoothly distribute power from the engine, motor and generator.