Save Mode V Charge Mode

[Stu]

At the weekend I had a 120 mile motorway journey then after the motorway a 20 mile drive on a 40mph limit to get home.

When I joined the motorway I set the cruise control at 70 and hit save mode. I had 10 EV range left and wanted to keep that for the 40mph limit road, where it would last longer than on the motorway. While in save mode the car charged the battery when it could and the EV range crept up to 12 and the car switched to EV mode until the range dropped back to 10, rinse and repeat. Although the range went up to 12, at 70mph I obviously didn't get anywhere near 2 miles of EV.

I then changed to charge mode and it behaved exactly the same as save mode, charging only when it could, except it kept on going instead of retaining a set level. When I came off the motorway I had 19 miles of EV range to use rather than the 10 if I'd stayed in save mode.

I've always read on here that charge mode is the work of the devil, but realising that charge mode is really just the same as save mode, except it keeps going, made me think that for this particular journey I probably saved a little bit of petrol by using it. Effectively I traded the odd 1/2 mile of EV driving on the motorway to gain 9 more miles of EV range to use on the 40mph limit road, where it would be more efficient. Granted we're probably only talking a few miles saved*

Is there method in my madness or have I got that completely wrong?

*maby disclaimer

 

[maby]

At the weekend I had a 120 mile motorway journey then after the motorway a 20 mile drive on a 40mph limit to get home.

When I joined the motorway I set the cruise control at 70 and hit save mode. I had 10 EV range left and wanted to keep that for the 40mph limit road, where it would last longer than on the motorway. While in save mode the car charged the battery when it could and the EV range crept up to 12 and the car switched to EV mode until the range dropped back to 10, rinse and repeat. Although the range went up to 12, at 70mph I obviously didn't get anywhere near 2 miles of EV.

I then changed to charge mode and it behaved exactly the same as save mode, charging only when it could, except it kept on going instead of retaining a set level. When I came off the motorway I had 19 miles of EV range to use rather than the 10 if I'd stayed in save mode.

I've always read on here that charge mode is the work of the devil, but realising that charge mode is really just the same as save mode, except it keeps going, made me think that for this particular journey I probably saved a little bit of petrol by using it. Effectively I traded the odd 1/2 mile of EV driving on the motorway to gain 9 more miles of EV range to use on the 40mph limit road, where it would be more efficient. Granted we're probably only talking a few miles saved*

Is there method in my madness or have I got that completely wrong?

*maby disclaimer

Hmmm, like the disclaimer!

What you have not mentioned, and may not have considered, is the effect on MPG. Your objective is, presumably, to minimise your overall running costs and it's not at all clear that this strategy will do it.

It is true that the charge level will creep up at times while you are in "Save Mode", but my belief is that this is as a result of the car running the engine at its most efficient level and dumping the spare output into the battery. When the charge level has crept up a bit, it drops back to pure EV mode to use that charge - hence keeping the battery at more or less the level it was when you pressed the button. This is rather similar to the way a Prius works - keeping the engine running close to its most efficient point on the power curve and capturing the spare output to use later.

In "Charge Mode", it will configure itself to bring the battery level up and engine efficiency will not be an important factor in its calculations. Depending on your road speed, I guess that the selected engine speed may be the optimum for efficiency, but that would be coincidental. The Outlander cruising at 55 in Save Mode can do over 40mpg. If putting it into Charge Mode brings that down to 30mpg but gives you enough charge to run an extra 5 miles in EV mode, you don't have to drive very far before you are wasting petrol, do you?

 

[jaapv]

At 70 MpH and over the car is barely to not able to charge the battery, as all ICE power is used to drive the car and supply the electric motors.

 

[maddogsetc]

The Jury's out on this for me. What's really required is for someone to do a back to back test with a journey like Stu's, first using Charge and the Save. But obviously it will be very difficult to guarantee near identical traffic, weather etc.

I tend towards Stu's logic - if the most efficient way to use the car at speeds between 45-70mph is parallel hybrid mode then allowing it to expend the surplus charge at higher speed seems to make less sense than storing it up for slow speed driving which would otherwise be in series hybrid mode.

I don't buy the idea that the engine is reconfigured to run significantly differently in Charge mode as opposed to Save - I suspect it's rather more simplistic than that.

But the only way we'll get a real idea of which version of events is true is for enough of us to do the test and compare the results. Unfortunately I don't do enough motorway miles to be able to provide much input here.

 

[jaapv]

It is more simplistic. In charge the car attempts to run the charge up to 80%, in save it attempts to keep the charge approximately at the same level. As there is less and less energy coming from the ICE to the battery due to increasing speed and thus energy demand for driving, the car is not able to increase the charge, so save and charge modes will operate the same way, i.e. maintaining the charge as high as possible. As speed increases more the car is not able to maintain the set charge level, and will find a lower balance.

 

[maby]

The Jury's out on this for me. What's really required is for someone to do a back to back test with a journey like Stu's, first using Charge and the Save. But obviously it will be very difficult to guarantee near identical traffic, weather etc.

I tend towards Stu's logic - if the most efficient way to use the car at speeds between 45-70mph is parallel hybrid mode then allowing it to expend the surplus charge at higher speed seems to make less sense than storing it up for slow speed driving which would otherwise be in series hybrid mode.

I don't buy the idea that the engine is reconfigured to run significantly differently in Charge mode as opposed to Save - I suspect it's rather more simplistic than that.

But the only way we'll get a real idea of which version of events is true is for enough of us to do the test and compare the results. Unfortunately I don't do enough motorway miles to be able to provide much input here.

I do some moderate motorway runs and have tested it informally - my overall fuel consumption seemed to rocket and I haven't tried it again. I think it is going to be difficult for me this time of year - the driving conditions are too variable and I would not anticipate the difference over a trip of around 70 miles to be big enough to drown out that variability.

I don't think that the engine needs to be "reconfigured" - fuel consumption is closely linked to loading anyway. You check your fuel consumption over 100 miles with just you in the car and the same trip with four adults and the back full of luggage - in the latter case you will burn more petrol. The same will be true if the generator is working hard to charge up the battery.

 

[user 422]

I Don't think its quite like that....
In Serial Drive mode the engine is able to set its RPM/power level so the generator produces the required amount of power into the system - BUT in Parallel drive the ICE is locked to the Front axle and from around 40MPH the engine RPM is 1500 and increases as the road speed goes up - the Generator is thus running at a LOW RPM which is too low to produce enough energy to charge the Battery at maximum rate as the road speed increases and providing the increase is gradual no demand is made by the Electric motors so Battery charge rate increases with speed - in charge mode if you then ease off the cruise the ICE clutch can disengage and the ICE RPM is then used to maximise the Battery charge rate - as the whole process is dynamic this is a constantly changing state and the dashboard display is a second or so behind what is actually happening - i.e. maybe the designers thought that you don't really need to know exactly what is happening at every instant...
In principle:-
Save Mode - Fuel consumption is exactly the same rate as it would be if you left the battery to discharge to its lowest level...
Charge Mode - Fuel consumption WILL be higher as the SYSTEM will try to use the ICE to maximise the Battery charge rate providing you are not demanding acceleration from the drive system, if you are constantly having your foot on the floor followed by significant braking and never cruise at a reasonable speed ( 65-75 ) your MPG will be significantly worse than not using charge mode....
( it takes approx 30min running the ICE when stationary to charge the battery to 80% and uses around 1 - 1.5 ltr of fuel ) The energy to charge the Battery has to come from a fuel source - turning on CHARGE mode is like adding 3 people and luggage - it is an extra load to lug around...

 

[maddogsetc]

I then changed to charge mode and it behaved exactly the same as save mode, charging only when it could, except it kept on going instead of retaining a set level. When I came off the motorway I had 19 miles of EV range to use rather than the 10 if I'd stayed in save mode.

Stu, how long were you in Charge mode to gain those extra 9 miles and also, was that increase actually reflected in the Charge gauge? As we all know the predicted range is based on restaurant maths and an increase of 9 miles could all be down to the road conditions being less demanding in the preceding period and therefore the car 'thinking' that it can travel farther on the same charge.

 

[CJ1045]

Save Mode - Fuel consumption is exactly the same rate as it would be if you left the battery to discharge to its lowest level...
Charge Mode - Fuel consumption WILL be higher as the SYSTEM will try to use the ICE to maximise the Battery charge rate providing you are not demanding acceleration from the drive system, if you are constantly having your foot on the floor followed by significant braking and never cruise at a reasonable speed ( 65-75 ) your MPG will be significantly worse than not using charge mode....
( it takes approx 30min running the ICE when stationary to charge the battery to 80% and uses around 1 - 1.5 ltr of fuel ) The energy to charge the Battery has to come from a fuel source - turning on CHARGE mode is like adding 3 people and luggage - it is an extra load to lug around...

I am not SURE that this is true. It all depends on how agressive the charge mode is. We have seen that in save mode that the car will charge a little higher than when you pressed the SAVE button and then later will use that extra charge in EV mode for a while until the charge depletes again to the save point. It seems to me that the general assumption here is that extra charge comes from regeneration when freewheeling, going down hill etc. There also appears to be an assumption that in CHARGE mode the car throws all it can at the batteries to charge them up and so use a fair bit more fuel. HOWEVER, it is possible that in charge mode the car could simply charge like it does in SAVE mode from regen but without the SAVE level cap, I beleive it is now 80%. It is possible then that this CHARGE mode EV power could then be used for the town section at the end of the trip and be more efficient and not rapidly discharged on the motorway like SAVE mode when it is not so efficient.

On the flip side you can go into CHARGE mode when stationary which does not appear to be efficient.

This then boils down to the question as to whether what actually occurs in CHARGE mode varies depending on the drving conditions of the car.

It woud be VERY interesting to know. As has laready been pointed out it is almost impossible to do a meaningful test ourselves as recreating the same conditions and measurement accuarcy are both very difficult. However, Mitsubishi WILL KNOW.

EDIT I have sent a detailed query to Mitsubishi UK referencing this discussion.

CJ

 

[Stu]

Stu, how long were you in Charge mode to gain those extra 9 miles and also, was that increase actually reflected in the Charge gauge? As we all know the predicted range is based on restaurant maths and an increase of 9 miles could all be down to the road conditions being less demanding in the preceding period and therefore the car 'thinking' that it can travel farther on the same charge.

I'd guess about an hour and a bit. The gauge was round about three quarters, so it probably got close to 80%. I wish I'd looked at the gauge before, now that you mention it.

it is possible that in charge mode the car could simply charge like it does in SAVE mode from regen but without the SAVE level cap

This is what threw me. I expected hitting charge mode to send the engine into a roar and constantly charge the battery, but it behaved exactly the same way as save mode and only sent charge when the engine could (and through regen), according to the animated screen on the trip page at least. However, I'd agree that this is probably only the case at motorway speeds.

 

[CJ1045]

It potentially does that mean that the efficient thing to do on a motorway is to select CHARGE rather than SAVE though just before you get on. You never know Mitsubishi may get back with a definitive answer based on the knowledge of how the system actually works.

CJ

 

[maby]

Save Mode - Fuel consumption is exactly the same rate as it would be if you left the battery to discharge to its lowest level...
Charge Mode - Fuel consumption WILL be higher as the SYSTEM will try to use the ICE to maximise the Battery charge rate providing you are not demanding acceleration from the drive system, if you are constantly having your foot on the floor followed by significant braking and never cruise at a reasonable speed ( 65-75 ) your MPG will be significantly worse than not using charge mode....
( it takes approx 30min running the ICE when stationary to charge the battery to 80% and uses around 1 - 1.5 ltr of fuel ) The energy to charge the Battery has to come from a fuel source - turning on CHARGE mode is like adding 3 people and luggage - it is an extra load to lug around...

I am not sure that this is true. It all depends on how agressive the charge mode is. We have seen that in save mode that the car will charge a little higher than when you pressed the SAVE button and then later will use that extra charge in EV mode for a while until the charge depletes again to the save point. It seems to me that the general assumption here is that extra charge comes from regeneration when freewheeling, going down hill etc. There also appears to be an assumption that in CHARGE mode the car throws all it can at the batteries to charge them up and so use a fair bit more fuel. HOWEVER, it is possible that in charge mode the car could simply charge like it does in SAVE mode from regen but without the SAVE level cap, I beleive it is now 80%. It is possible then that this CHARGE mode EV power could then be used for the town section at the end of the trip and be more efficient and not rapidly discharged on the motorway like SAVE mode when it is not so efficient.

On the flip side you can go into CHARGE mode when stationary which does not appear to be efficient.

This then boils down to the question as to whether what actually occurs in CHARGE mode varies depending on the drving conditions of the car.

It woud be VERY interesting to know. As has laready been pointed out it is almost impossible to do a meaningful test ourselves as recreating the same conditions and measurement accuarcy are both very difficult. However, Mitsubishi WILL KNOW.

CJ

With so many different discussion threads running on related topics, I've been keeping quite a close eye on the energy flow displays in a variety of driving conditions and I'm pretty sure that charge mode is more aggressive than this.

The additional charge gained in Save Mode is not restricted to the output of regeneration - there are significant periods of explicit flow from the generator into the battery. The rate of charge in Save Mode is low - it takes several minutes to put on one mile of additional EV range. As jaapv points out, the strategy will have to differ depending on road speed - below about 50mph, it is constrained to operate in serial hybrid mode because the engine revs would be too high to couple directly to the front wheels. Under these circumstances, the control systems have the freedom to do anything they want with the engine revs and I assume that they operate the engine close to best efficiency, dumping any excess output into the battery till there is enough to justify dropping back to EV for a mile or two. This is a very efficient mode of operation and can easily return 43mpg.

As the road speed goes above 50mph, the car tends to switch to parallel hybrid mode. When you get above something like 70mph, it has no choice. In parallel mode, the engine speed is directly linked to the road speed and the car has no freedom to balance it for improved efficiency. Any spare output goes into the battery but, as jaapv points out, there will not be very much.

I suspect that the difference between save mode and charge mode will be pretty small at high road speeds - there is not enough spare output from the engine to do much more than save. At lower speeds, the difference is much greater - in save mode, the car is trying to maximise fuel economy and is playing with power flows to achieve that. When you put it into charge mode, you are telling it that you don't care about fuel economy and want a full battery - and it will behave accordingly.

 

[gwatpe]

All these discussions could be made easier IF THERE WAS A NUMBER INDICATION OF THE POWER IN AND OUT OF THE BATTERY. The generator power minus what is going to the wheel motors would solve the guessing. This car has a traction battery but no direct display of power in or out of it except in EV only mode with about 30 minutes typical useful driving range per day. Not real useful on a longer trip with say ICE operation required.

The %EV driving does not reflect the real use of energy when the petrol motor operates.

PHEV drivers are shackled by lack of instrumentation that could make these whether to select a particular mode, driving decisions easier, so many just give up and just drive till the battery is empty and continue with series/parallel hybrid determined by the car. I suspect there will eventually be many who don't even bother to recharge at every opportunity and just stop plugging it in.

My typical drives dictate using SAVE mode, so I would like to see some last drive memory retention of settings, like SAVE/ECO and others. Even a user set preferred SAVE battery level, apart from EMPTY would be good.

 

[jaapv]

I think you are missing the basic idea of the car. It is meant to be driven without the driver needing to worry about controlling its mechanism, not to be played by constant button pressing. In my experience trying to override it results in less efficient driving, it is hard to beat the computer.
let it do it's own thing and use the buttons as they were intended:
Save tells the car that you want some electrical reserve, eg on the motorway, and/or with town traffic ahead.
Charge tells the car that you will need full electric power ahead, like approaching an emission-restricted zone or mountains. Keep it engaged in the mountains.
Eco engages a mode that produces a toned down performance/heating-AC ( and has little effect in my hands, I stopped using it)
The paddles are essential on downhill slopes and just add a little fun for the rest of the time
The displays are intended as entertainment.
That is it.
Sit back, let the car do its thing and you will get the best results.
27000 Kms have taught me this....

 

[Regulo]

The only time I've used Save is so that I can impress someone with pure EV at the other end of my journey! :twisted:

Got to agree with jaap, mostly find the car can manage itself OK without my help - I think it's brainier than I am! (Not difficult).

 

[CJ1045]

I did get this reply from Mitsubishi UK which does not fill in the gaps in our knowledge unfortunately:

As stated in the owner’s manual, section 7 page 22 onwards; the battery charge button can be used to increase the quality of the drive battery. For example, you could use the battery charge switch before driving up a long hill, steep slope or mountain and it will maintain the drive force performance.

As you can appreciate, if you use the battery charge function to generate EV battery power whilst the combustion engine is the main driving force, the fuel consumption may increase.

The battery save button can be selected if you are traveling at higher speeds and wish to save your battery for slower town driving.

When driving at a continuous low to medium steady speed, for example, 30-40 mph the vehicle will try to account for any lights, heating, air conditioning, etc running and transfer any excess power from regenerative braking to the EV battery to enable it to charge. In the event that the speed increases, for example 60-70 mph, the vehicle will recognised that more power is required to drive the vehicle, which will result in less, if any, excess power being transferred to charge the battery.

Regretfully, we do not have specific figures or case studies to prove how ‘aggressive’ the CHARGE or SAVE modes are in charging the EV battery. As you can appreciate, there are so many variable to take into consideration. Unfortunately the vehicle has not been in production for long enough for such comprehensive data to be obtained and researched.

Kind regards

Samantha


CJ

 

[gwatpe]

I have just returned from a week away, with all days driving, with no power cord recharging available. The CHARGE button came in handy when I had forgotten to press the SAVE button to bring the battery level back up around half way. Why can't the car be programmed to just remember the last setting? The car works really well in SAVE mode. Just need to remember to push SAVE at the start of any drive. I only use NORMAL mode in stop/start traffic, or short local drives. Everyone's daily drive will be different and for some, Normal mode may be OK. I have even been guilty of showing off the 0 L/100km on occasions. It really means that I have not driven far. My control button usage will change as the price of petrol changes, and my driving habits become restricted to more local driving as well. At the moment the PHEV has too little battery capacity, to waste it on highway driving. I am still in 2 minds whether SAVE is better than CHARGE. The road conditions do play a significant part, and sometimes with ACC on bumpy roads, it may be better to have a more fully charged battery to improve the passenger comfort.

 

[maby]

Putting it into Save mode seems to switch the algorithm closer to the one used by Toyota in their hybrid range - a more active play-off between petrol and battery. I've now arrived at a point where if I know that I'm going to be doing more than around 50 miles before my next charge, I also tend to press Save once I'm down to around 50% charge - it does seem to result in a happier car.

If anyone from Mitsubishi is reading this forum, perhaps they could consider offering this as a third mode?

 

[Regulo]

Will this help:

http://insideoutlander.boards.net/thread/471/available-power-cruising

Means diddly-squat to me! But it might mean something to you.

 

[gwatpe]

Hi Regulo,

I have added a HUD to my PHEV and once you see the actual L/100km and cross reference this with the dash indicators as well as the road conditions all the theory is pure theory.

With the clutch engaged in parallel hybrid mode, the ICE at constant vehicular road speed can consume an additional 50% more petrol with no change in battery power, just with a change in the terrain slope, or even the head wind the car is experiencing. This surely relates to a change in power available at a fixed engine rpm, and not some constant power with rpm.

The governing ability of the ICE has to interact with the car programming for the battery usage as well.

It does seem to take forever to put energy back into the battery at highway speeds. I have found that 70-80kph has a better effect. The car seems to work better in parallel hybrid for most effective charging. Probably with this being generally the most efficient use of the ICE.

On one drive, at 100kph, in charge mode, my PHEV took approx 1 hour to recharge 50%.