petrol consumption

[gwatpe]

I know there is a lot of theory re how the PHEV matches up with other similar vehicles on the economy scale. I have recently driven many km as a petrol car, with a returned economy on the highway of just over 8L/100km. A mate has recently purchased the Challenger, a slightly bigger SUV, still a MMC vehicle. His returns 14L/100km. He could have purchased a PHEV.

If my drive has an average of half EV only driving, then I would see the 4L/100km and this would be future typical. My electricity for recharging is free solar.

with say 20000km driven per year, I would use about $1120 of petrol. My mate would use approx $3920 per year. Both cars need servicing, and this is a similar on cost. My mate would take about 12 years to use the car cost in petrol at today's price. I would take almost 45 years. When it comes to replacing my PHEV, I will have a nice saving of petrol money to buy again. My mate will not be so lucky.

Tax savings would be just icing on the cake.

 

[PolishPilot]

I know there is a lot of theory re how the PHEV matches up with other similar vehicles on the economy scale. I have recently driven many km as a petrol car, with a returned economy on the highway of just over 8L/100km. A mate has recently purchased the Challenger, a slightly bigger SUV, still a MMC vehicle. His returns 14L/100km. He could have purchased a PHEV. If my drive has an average of half EV only driving, then I would see the 4L/100km and this would be future typical.

I can confirm your numbers. 8l/100km highway, 3,5l/100km usual city drives. Unfortunately with Polish colder climate
some worse figures in winter, hence over 17000km my average is 5,2l/100km.

My electricity for recharging is from grid, but, nevertheless the savings are big.

Tax savings would be just icing on the cake.

Unfortunately no tax savings in Poland, so I will just have the cake.

 

[jaapv]

I know there is a lot of theory re how the PHEV matches up with other similar vehicles on the economy scale. I have recently driven many km as a petrol car, with a returned economy on the highway of just over 8L/100km. A mate has recently purchased the Challenger, a slightly bigger SUV, still a MMC vehicle. His returns 14L/100km. He could have purchased a PHEV.

If my drive has an average of half EV only driving, then I would see the 4L/100km and this would be future typical. My electricity for recharging is free solar.

with say 20000km driven per year, I would use about $1120 of petrol. My mate would use approx $3920 per year. Both cars need servicing, and this is a similar on cost. My mate would take about 12 years to use the car cost in petrol at today's price. I would take almost 45 years. When it comes to replacing my PHEV, I will have a nice saving of petrol money to buy again. My mate will not be so lucky.

Tax savings would be just icing on the cake.

Solar is not free. You have to write off the solar panels and installation.

 

[gwatpe]

Solar is not free. You have to write off the solar panels and installation.

My solar paid for itself years ago. Get paid for surplus still and hopefully till 2028.

Food on the table is still a cost, and don't expect that to be free for some time.

 

[PeteInOz]

I must say that the 8L/100Km appears to be a little higher than what we have experienced to date. Our worst figure to date was 7.2L/100Km on a long haul trip and this was accurately measured between fuel stops filling the tank. Our average consumption over approximately 3,000Km on that long haul trip proved out to 6.4L/100Km. Out average speed was 100-110Km/hr as 110Km/hr is the legal limit on most east coast Australian roads.

This brings up a couple of observations. The first is in the Technical Highlights document that I supplied elsewhere on the forum where it suggests that drag from magnetic induction could reduce economic efficiencies at or above 120Km/Hr. Please refer to page 22 here:
https://dl.dropboxusercontent.com/u/106981165/PHEV/PHEV%20Outlander%20Technical%20Highlights%20for%20MMAL.pdf . However, I continue to wonder if drag is not present at lower speeds also (e.g. when various regen breaking levels are applied), which, and if my assumption is correct, might be affecting some driver's fuel economy observations.

In addition, the propaganda marketing video about charging (as supplied by Mitsubishi Australia) suggests that the onboard charger will consume approximately "up to 3L of fuel to fully recharge the drive battery from empty". If this is the case, then this suggests that based upon an approximate EV driving range of 52Km (or < 6L/100Km), that it might prove more economical to continually recharge the battery and utilise EV mode more often to garner better fuel economy .... though I accept this thinking and any results will very much depend upon certain driving conditions (i.e. at speed, drag from magnetic induction and normal aerodynamics could reduce overall range and therefore economy).

With the foregoing in mind, my thinking could very well be wrong but I offer it up for consideration in any case.

Cheers PeteInOz

 

[jaapv]

I cannot find anything about drag from induction there. On page 21, however, we find this:

In EV Mode:
• The loss of energy from the drive battery is mainly caused by the conversion
from DC voltage (300VDC) to AC voltage (300VAC) to feed the electrical
motors. In this conversion around 15% of energy is lost

Which is the normal conversion loss that has been mentioned before in the forum.
As the motors are permanently powered up, they will not exhibit drag imo.

 

[Neverfuel]

I cannot find anything about drag from induction there. On page 21, however, we find this:

In EV Mode:
• The loss of energy from the drive battery is mainly caused by the conversion
from DC voltage (300VDC) to AC voltage (300VAC) to feed the electrical
motors. In this conversion around 15% of energy is lost

Which is the normal conversion loss that has been mentioned before in the forum.
As the motors are permanently powered up, they will not exhibit drag imo.

Just to add to that - the only time there is redundancy in a motor is when the front motor is not used during parallel hybrid mode. However the engine supplies 2.8 kW to the front motor (2 kW after losses) through the generator to stop the front motor from dragging when the engine is used to power the front wheels (the motor is permanently attached through the front transaxle, whereas the engine can be disengaged via the clutch). This would then be cut off when regenerative braking comes into play when the drag can be used to slow the vehicle. I think!

 

[gwatpe]

I think that a point I should have made in my original post was that the average petrol consumption was based on "zero" electricity from the plug. I achieve really good consumption figures like everyone else when electricity from a plug is mixed in with the petrol.

My point really was about the scale of savings that can be rewarded compared to a similar petrol only vehicle.

 

[Neverfuel]

In addition, the propaganda marketing video about charging (as supplied by Mitsubishi Australia) suggests that the onboard charger will consume approximately "up to 3L of fuel to fully recharge the drive battery from empty". If this is the case, then this suggests that based upon an approximate EV driving range of 52Km (or < 6L/100Km), that it might prove more economical to continually recharge the battery and utilise EV mode more often to garner better fuel economy .... though I accept this thinking and any results will very much depend upon certain driving conditions (i.e. at speed, drag from magnetic induction and normal aerodynamics could reduce overall range and therefore economy).

Just a couple of points:

I don't think that the charge mode will get the SOC back to 100% - it charges up to 86% and then the car will drive on EV until it drops to around 80%, then starts the charging cycle again. However, when charging at the upper end of the SOC,the current will be smaller so that the individual cells in the battery can be levelled - so it is probably very inefficient to continually run with charge selected as the engine will run at 1700 rpm when the vehicle is moving, rather than 1100 rpm when stationary, giving less charge to the battery in the process.

The battery will not charge when the car is being driven at high speed or under significant load in parallel hybrid as it needs the power to move the car forward. The amount of power consumed at higher speeds is significantly greater, and the torque output from the motors is significantly less effective when the motors are turning at high speed (due to "back emf" - I think - Maby will correct me on that if I am wrong) for the same power consumption. There is also the increased amount of torque required to overcome aerodynamic drag (drag increases as the square of speed, so twice as fast = 4 times the drag, three times as fast = 9 times the drag etc). So there is a "sweet spot" where the drag is low, the motors are spinning at the lower end of their range and the car is in series hybrid mode, plus the SOC is between certain limits that will allow the battery to charge quickly, without trickle charging. It may be, that if you can meet all these conditions, and the road conditions are suitable, that you might get a better range / fuel economy, but you would have to keep turning the charge button on/off when the conditions were not met. You would also still be burning about 20% more fuel during the charging periods than if you just let the car do it's own thing in series hybrid mode when the SOC reduced down to 30%. Obviously though, if you will need a power boost later in your journey, using the charge button is well advised.

 

[gwatpe]

I don't think that the charge mode will get the SOC back to 100% - it charges up to 86% and then the car will drive on EV until it drops to around 80%, then starts the charging cycle again. However, when charging at the upper end of the SOC,the current will be smaller so that the individual cells in the battery can be levelled - so it is probably very inefficient to continually run with charge selected as the engine will run at 1700 rpm when the vehicle is moving, rather than 1100 rpm when stationary, giving less charge to the battery in the process.

A couple of points.

There are differences in programming of our PHEV's depending on the region we bought the car.

If you have 2 plug recharging sockets then you may see the charge mode operation quoted above.

If you have only the one AC socket, then the PHEV will allow the battery to be recharged to ~100%. 15+ bars. In the latter case, the CHARGE mode operation is essentially the same as SAVE mode or even an EMPTY battery. The difference is just how much energy is in the battery and whether the car is trying to fill the battery or not let the level go below a certain amount. The PHEV only loads the ICE with the surplus power to driving being able to be put into the battery when in CHARGE mode. This will vary dramatically depending on the state of charge level. As the battery becomes fully recharged, then it is only if the car is stationery that the efficiency of the process will be very inefficient. The electrics are smart enough to only allow CHARGE mode to fill the battery to 80% when the car is not moving. In AUS, the car will allow the battery to be filled to ~100% if driven. I have only confirmed this in parallel hybrid
mode, but I have seen ICE operation with a full battery in series hybrid mode, even in SAVE mode.

Is still winter so my driving is atypical and does not allow a routine for comparisons.

 

[maby]

I don't think that the charge mode will get the SOC back to 100% - it charges up to 86% and then the car will drive on EV until it drops to around 80%, then starts the charging cycle again. However, when charging at the upper end of the SOC,the current will be smaller so that the individual cells in the battery can be levelled - so it is probably very inefficient to continually run with charge selected as the engine will run at 1700 rpm when the vehicle is moving, rather than 1100 rpm when stationary, giving less charge to the battery in the process.

A couple of points.

There are differences in programming of our PHEV's depending on the region we bought the car.

If you have 2 plug recharging sockets then you may see the charge mode operation quoted above.

If you have only the one AC socket, then the PHEV will allow the battery to be recharged to ~100%. 15+ bars. In the latter case, the CHARGE mode operation is essentially the same as SAVE mode or even an EMPTY battery. The difference is just how much energy is in the battery and whether the car is trying to fill the battery or not let the level go below a certain amount. The PHEV only loads the ICE with the surplus power to driving being able to be put into the battery when in CHARGE mode. This will vary dramatically depending on the state of charge level. As the battery becomes fully recharged, then it is only if the car is stationery that the efficiency of the process will be very inefficient. The electrics are smart enough to only allow CHARGE mode to fill the battery to 80% when the car is not moving. In AUS, the car will allow the battery to be filled to ~100% if driven. I have only confirmed this in parallel hybrid
mode, but I have seen ICE operation with a full battery in series hybrid mode, even in SAVE mode.

Is still winter so my driving is atypical and does not allow a routine for comparisons.

My UK specification PHEV will certainly try to charge to 100% on the petrol engine - I have been stationary at traffic lights with the engine revving quite high as it tried to fill in the last brick on the gauge...

On a separate subject - please all be very careful when reversing of lampposts that jump out unexpectedly and maliciously break the lens of your rear light cluster! I'm £270 the poorer today having broken the plastic lens - you can't purchase individual components - it's a complete module that comes fitted with bulbs and a section of wiring loom attached - ouch!

 

[PeteInOz]

I cannot find anything about drag from induction there. On page 21, however, we find this:

In EV Mode:
• The loss of energy from the drive battery is mainly caused by the conversion
from DC voltage (300VDC) to AC voltage (300VAC) to feed the electrical
motors. In this conversion around 15% of energy is lost

Which is the normal conversion loss that has been mentioned before in the forum.
As the motors are permanently powered up, they will not exhibit drag imo.

Thanks for the comments jaapv.

As I have previously stated elsewhere, I tend to think that the 15% DC to AC conversion loss you mention is rather poor in this day and age given that, and by comparison, roof top solar inverters will only lose about 5-6% on average (i.e. they are typically 94-97% efficient in DC to AC conversion).

In regards to the losses due to drag, well this is what is specifically stated on Page 22 (second paragraph):

'In the graphs for the front and rear motors we can see that the torque of the motors is getting lower as speed increases. At maximum speed the motor performance is almost zero. At higher speeds the efficiency of the electric motors reduces. The electric motors get less efficient at higher speeds because the electro magnetic force induced works against the driving force. For this reason it is more efficient to use the engine above 120Km/hr.'

 

[jaapv]

I see. That is not drag, that is Counter EMF, reducing efficiency at high RPM. Any electric motor with a rotating armature will exhibit it.
https://en.wikipedia.org/wiki/Counter-electromotive_force

As for conversion losses, we are talking about a battery-inverter-motor chain here. That is not the same as conversion from solar panels.
Also the amount of power drawn is a factor, efficiency may drop as low as 50% in some cases. It is not possible to compare without taking all factors into account:
http://www.solar-facts.com/inverters/inverter-efficiency.php

 

[gwatpe]

The aerodynamic drag relation to speed has been quoted as a squared relation. It is actually a cubic relation. Pushing a brick twice as fast will require 8 x the power to overcome the aerodynamic drag component.

My involvement with the World Solar Challenge race had me conclude that getting the aerodynamic shape right was as important as the electrics.

 

[greendwarf]

On a separate subject - please all be very careful when reversing of lampposts that jump out unexpectedly and maliciously break the lens of your rear light cluster! I'm £270 the poorer today having broken the plastic lens - you can't purchase individual components - it's a complete module that comes fitted with bulbs and a section of wiring loom attached - ouch!

Been there, seen it (or rather NOT), done it

 

[biosci]

The aerodynamic drag relation to speed has been quoted as a squared relation. It is actually a cubic relation. .

Actually it is a squared relation (various sites):

"In fluid dynamics, the drag equation is a formula used to calculate the force of drag experienced by an object due to movement through a fully enclosing fluid. The formula is accurate only under certain conditions: the objects must have a blunt form factor and the fluid must have a large enough Reynolds number to produce turbulence behind the object. The equation is

D = Cd * A * .5 * r * V^2
D is the drag force, which is by definition the force component in the direction of the flow velocity,[1]
r is the mass density of the fluid, [2]
V is the flow velocity relative to the object,
A is the reference area, and
Cd is the drag coefficient – a dimensionless coefficient related to the object's geometry and taking into account both skin friction and form drag. "

 

[PeteInOz]

I see. That is not drag, that is Counter EMF, reducing efficiency at high RPM. Any electric motor with a rotating armature will exhibit it.
https://en.wikipedia.org/wiki/Counter-electromotive_force

As for conversion losses, we are talking about a battery-inverter-motor chain here. That is not the same as conversion from solar panels.
Also the amount of power drawn is a factor, efficiency may drop as low as 50% in some cases. It is not possible to compare without taking all factors into account:
http://www.solar-facts.com/inverters/inverter-efficiency.php

Thanks for the input and links Jaapv.

Whilst I have been out of the engineering game for nearly 20 years now, as a retired electronics engineer myself, I believe my use of the term 'drag' is technically correct and appropriate in the context in which I have used it, both here and elsewhere on the forum, as the eddy currents that are produced within the motors and within the regenerative braking system produce a drag force (i.e. Lenz's Law), which is just the back-EMF or 'counter EMF' you speak of. I have tended to use the term 'drag' more generically as I feel most people on the forum would more instinctively know what affect 'drag' actually produces ... as opposed to using such terms as back or 'Counter EMF'.

Anyway, back to things more relevant, the issue and concern about drag is what I originally raised elsewhere on the forum with respect to regenerative breaking. Given that I have been out of the engineering game for so long now I was interested to know if and what advances might have been made in this area. Whilst the technical document I have provided provides some good high level technical detail there appears to be little detail of the regenerative braking system itself. Given the experiences to date of members undertaking long haul trips and the way eddy current braking / regenerative breaking generally works, then I suspect that drag may still be inherent (and may become more pronounced at higher speed for a host of different reasons) if regen breaking remains activate within the mix. Whilst I can't be sure, I suspect members may be marginally better off on long haul trips if regenerative breaking was disabled altogether until it was absolutely necessary. I suspect this is why Mitsubishi has included the paddles as an additional feature / mechanism, so as to enable people to reduce the effects of drag (not explicitly stated) but then be able to proactively apply regen breaking on the odd occasion where breaking would prove beneficial. I would welcome other thoughts on this.

In regards to the issue of 'conversion losses' as stated, well if the technical highlights manual is correct (i.e. please refer to page 17 and again page 19), then the 15% loss stated is just for the DC -> AC conversion and does not take into account any additional losses within the motor(s) or drive train. However, upon re-reading the references, they explicitly state 'inverters', which suggests plural. If this reading is correct, then one could reasonably conclude that the 15% is a total loss from both inverters combined, which if taken on an individual basis, is not so bad as I had originally thought and stated.

I hope this helps ...

Cheers PeteInOz

 

[jaapv]

You're as out of date as I am My Bachelor's in Engineering at Delft University is is a lifetime ago...
I like to think that Mitsubishi put quite some thought into the efficiency of the system and the parameters involved, which should translate in the algorithms used in the software. Actually it must be a highly complex exercise to adapt the car to the variations of use.

OTOH I have a sneaky and unworthy suspicion that the paddles are there for the simple reason that they were available anyway and that the function was dreamed up for marketing reasons.

 

[gwatpe]

The aerodynamic drag relation to speed has been quoted as a squared relation. It is actually a cubic relation. .

Actually it is a squared relation (various sites):

"In fluid dynamics, the drag equation is a formula used to calculate the force of drag experienced by an object due to movement through a fully enclosing fluid. The formula is accurate only under certain conditions: the objects must have a blunt form factor and the fluid must have a large enough Reynolds number to produce turbulence behind the object. The equation is

D = Cd * A * .5 * r * V^2
D is the drag force, which is by definition the force component in the direction of the flow velocity,[1]
r is the mass density of the fluid, [2]
V is the flow velocity relative to the object,
A is the reference area, and
Cd is the drag coefficient – a dimensionless coefficient related to the object's geometry and taking into account both skin friction and form drag. "

The power of the wind vs wind speed is a cubic relationship. This is used for calculating wind farm locations. The same air that a car has to use power to push itself through. I suggest anyone interested, performs a dimension analysis of any equations and there will be parts of the equation not just V^2 that equate to another V.

http://www.iowaenergycenter.org/wind-energy-manual/wind-and-wind-power/wind-speed-and-power/

I won't be debating this as it has been done to death on windmill forums elsewhere.

 

[Grigou]

IMHO there is no more drag in B5 than in B0 (at the same stable speed of course). Bx only affects the effects of the positions of the accelerator pedal.
At the same speed, the pedal will be more depressed in B5 than in B0 and give the same result.