I use charge mode for better fuel consumption.

[anko]

Trex was talking about doing this at motorway speeds of 110 kmh. So, in parallel mode. He is actually aiming at building up / saving SOC for slow stretches.

But even when you do this at lower speed, there is not much difference between running in Charge mode or normal mode, except for the actual pattern. I would however try to prevent running save mode while parked for a traffic light, because then the engine is running purely for charging which is far less efficient.

 

[maby]

Trex was talking about doing this at motorway speeds of 110 kmh. So, in parallel mode. He is actually aiming at building up / saving SOC for slow stretches.

....

I don't think that is what he is doing - read his post again : "Anko, you are mistaken on what I am doing when on the freeway. I am running in Ev mode till it runs out of charge then putting the car in charge mode till the hv battery gets to a level that is less than 80%, where it would stop charging anyway, (I actually only go to 50%, takes about 1/2 an hour) then back to ev mode till it runs out of charge then back to charge mode etc. etc."

He seems to be running for a long period at speeds where the car is able to operate in pure EV mode, allowing the battery to go flat, then engaging Charge mode till he gets up to 50% or more, then going back to normal mode till the battery runs flat again. I don't see how that can be more efficient than either staying in Save mode, or just letting the battery run flat and operating in serial hybrid from then on - he is introducing the losses of charging and discharging the battery when the power could have been going directly from the generator to the battery.

 

[anko]

Somehow, it feels like you are missing the point.

Without Charge mode, the engine is intermittendly turned on and off automatically. When the engine is on, it drives the front wheels and some of the surplus power that is available is stored in the battery, allowing for the next period of engine off. This happens with SOC going up and down between 30 and 32% (normal mode) or with SOC going up and down between X and X+2% (save mode).

What Trex does is exactly the same, except that this time the driver decides how long the engine is on, before it is being turned off. And SOC is going up and down between 30 and 50%. But there is no difference in actual driving modes or energy flows. As long as you do not wait to long before turning off the engine (and end up on your driveway with some SOC left), there is no solid reason why this should be more or less efficient.

Btw: Except for moments where more power is needed (acceleration, climbing), the car will not go to series hybrid mode at speeds above 65 kph (40 mph), as that would really be inefficient. It will either be parallel mode or EV mode at these speeds.

 

[maby]

Somehow, it feels like you are missing the point.

....

I just ran a test (admittedly over quite a short distance) and I'm not convinced. I left the house with a fully charged battery and immediately engaged Charge mode - it allowed me to do so - so, first discovery - Charge mode does not cancel itself - it stays on till you turn it off.

I drove a couple of miles with charge mode engaged and it was looking good as an option for long distance driving - after an initial period with the engine running to warm the car up, it dropped to EV mode with occasional periods of engine on acceleration - the car was very responsive. I was getting about 43mpg which is good for long distances.

But then I had to stop for a while and it all fell apart. I restarted and selected Charge again - but with a 90% battery. Now it ran the engine almost all the time - seemed to be trying for 100% charge. The battery was showing just one bar off full, but I was sitting at the traffic lights with a warm car and the engine running! So, not a set and forget option for long distance trips - pity... I got home having done 5 miles in reasonably warm weather and showing 25 mpg.

 

[Grigou]

Agree with you, maby : in Save mode, the "1" are of course more efficient !

You have precisely pointed why Mitsu doesn't recommand Charge mode except for a few particuliar purposes (especially for towing).

 

[anko]

Agree with you, maby : in Save mode, the "1" are of course more efficient !

Sorry, but the "1" in Save mode is exactly the same as a "1" in Charge mode.

 

[anko]

... - Charge mode does not cancel itself - it stays on till you turn it off.

... it dropped to EV mode with occasional periods of engine on acceleration - ...

Now you got me confused. Did it or did it not stick in Charge mode?

... but I was sitting at the traffic lights with a warm car and the engine running!

Sitting at a traffic light at 40+ mph? I thought we were talking about a strategy for highway cruising, not city traffic?

Of course, in city traffic you want to EV as much as possible. Charging does not make sense at all.

 

[maby]

... - Charge mode does not cancel itself - it stays on till you turn it off.

... it dropped to EV mode with occasional periods of engine on acceleration - ...

Now you got me confused. Did it or did it not stick in Charge mode?

... but I was sitting at the traffic lights with a warm car and the engine running!

Sitting at a traffic light at 40+ mph? I thought we were talking about a strategy for highway cruising, not city traffic?

Of course, in city traffic you want to EV as much as possible. Charging does not make sense at all.

Sorry - I'm not being sufficiently clear. I left the car in Charge mode all the time - it doesn't automatically cancel it. By "dropped doen to EVmode" I meant that the engine stopped and it ran on battery for a while.

In the city, you want EV mode if you are going to be able to charge up again later - I was looking for a better strategy for multiple days of mixed mode driving without the ability to charge. I was hoping that selecting Charge mode with a full battery would give a "set and forget" solution for long periods away from a charger - it doesn't!

 

[Trex]

Gday,

Basically my strategy is to keep the petrol motor off as much as possible, ie being in Ev mode as much as possible. So fuel consumption will be the ratio of fuel consumed petrol engine on and driving car and charging battery, to petrol engine off and consuming no fuel and depleting battery.

If I have to use petrol I will always press the charge button and try to be over 70kph , ie petrol motor driving front wheels and charging battery. Once the battery gets to 50%,about 1/2 an hour, (this can be taken to 80% where the battery will no longer be charged for say arriving at the destination and driving around town, in Ev mode, at the slower speeds), I then press the charge button again to go back to Ev mode.

On the freeway with no slow sections, in NSW where I live max speed is 110kph, my trip computer shows that I use slightly less petrol using this strategy than if I had just pressed the save button, ie 7.5lts/100ks compared to 8lts/100ks . For the small fuel savings this may or may not be worth it to you in having the extra button pressing to do.

But the bigger savings of petrol occur for me, if by planning ahead, is to have enough charge in the battery for the slower sections, ie running through towns or cities etc at the slower speeds ( in Ev mode ) then back at higher speed building up SOC for the next slow section.

I hope I am being clear with this post .

Regards Trex.

 

[Trex]

Hi Martinh,

About your first post in this discussion. I understand what you are saying, my background is mechanical and electrical engineering, but to pick up a couple of points.

The charge button will only charge the battery to 80% approx. So less than 10kwh ( about 8kwh).

Like I said my fuel trip computer shows 10lts/100ks in charge mode, ie charging battery and driving front wheels, but I do use 98 octane fuel (premium) if that makes a difference (hmm, have to try regular), at 110kph gps.

I appear to be using 2lts/100ks extra for charge mode ie increasing SOC, compared to save mode ( over time ) ie not increasing SOC.

Mitsubishi Australia claims you will use 20% more fuel for charge mode. Perhaps that what they mean ie 10lts/100ks charge mode 8lts/100ks no charge mode ie 2/10 =20%, when they should have said 2/8 =25% (you there Anko?), and they are not considering the extra Ev range you get from the charge button.

When it is all said and done I can only go on what my trip computer says which is seems very accurate against the old brim to brim refueling with manual recording and yes I have done the same trip in different modes.

Regards Trex.

 

[Trex]

Hi Maby,

Perhaps on your next trip away you could try this technique ie being in Ev mode as much as possible especially if you know the slow sections for forward planning.

What's to lose?

Regards Trex.

 

[Titan]

Hi Maby,

Perhaps on your next trip away you could try this technique ie being in Ev mode as much as possible especially if you know the slow sections for forward planning.

What's to lose?

Regards Trex.

I must admit, although I haven't quantified it, this is what I try and do. If I have motorway / open road I will try and use charge and when I come to towns / villages / traffic will turn off charge and use EV. My thinking being that if in traffic the engine will not be as efficient as when on the open road.

 

[greendwarf]

Without Charge mode, the engine is intermittendly turned on and off automatically. When the engine is on, it drives the front wheels and some of the surplus power that is available is stored in the battery, allowing for the next period of engine off. This happens with SOC going up and down between 30 and 32% (normal mode) or with SOC going up and down between X and X+2% (save mode).

.

Perhaps this is where the "saving" comes from by not wasting small amounts of fuel stop/starting compared to a longer period of continuous running?

 

[Grigou]

Agree with you, maby : in Save mode, the "1" are of course more efficient !

Sorry, but the "1" in Save mode is exactly the same as a "1" in Charge mode.

How can you be so certain ?
Have you some docs ? Or some measures of intensity ?

Did you try Save mode and Charge mode at low speeds ?
If yes, did you hear the ICE (when it was in "1" on Save mode, of course) ?
No difference on your car ?

In mine yes !

So my conclusion is that the currents are different, at least at low speeds.
And why not at high speeds ? (it's just a question, anko ).

 

[anko]

If I have to use petrol I will always press the charge button and try to be over 70kph , ie petrol motor driving front wheels and charging battery.

That seems to make sense. At least, that's what I do. Or more precisely "I will only press the charge button when I am over 70kph".

Once the battery gets to 50%,about 1/2 an hour, (this can be taken to 80% where the battery will no longer be charged for say arriving at the destination and driving around town, in Ev mode, at the slower speeds), I then press the charge button ...

Once you go above 50% SOC the rate of charging goes down a notch to protect the battery *). So, the instantaneous fuel consumption in terms of l/100km will be slightly less, when you go above 50% SOC. But in a car like ours, which will stop the engine every now and then, instantaneous fuel consumption is totally irrelevant. The only important thing is fuel efficiency (during the periods the engine is running). And when the charge rate drops, so does the load on the engine and so does the fuel efficiency.

Due to the higher charge rate, the periods of "engine on" will be shorter, as the amount of energy needed for the next "engine off" period is generated quicker. Shorter periods of "engine on" at a higher fuel efficiency lead to higher overall efficiency, even when the instantaneous fuel consumption during the "engine on" periods is higher. Let's not forget, if this was not true, the why would the car not simply go to parallel mode and not bother with charging?

*) I have actually seen this happening by monitoring instantaneous fuel consumption on an OBDII scanner, while driving 100 kmh on CC in one single direction on a very flat and empty road during which I enhanced SOC from 30% to 80%. The first drop in instantaneous fuel consumption is at approx. 50%. There are several drops at even higher SOC's.

On the freeway with no slow sections, in NSW where I live max speed is 110kph, my trip computer shows that I use slightly less petrol using this strategy than if I had just pressed the save button, ie 7.5lts/100ks compared to 8lts/100ks . For the small fuel savings this may or may not be worth it to you in having the extra button pressing to do.

Which makes me think: is it possible that you have engaged the Save mode at an SOC of more than 50%? Because, taking into account what I wrote above, that would IMHO result in a lower fuel efficiency than Charging and EVing back and forth between 30% and 50% SOC. I can imagine that if you go to Save mode at for example 75%, it could explain the reduced efficiency you have noticed.

 

[anko]

The charge button will only charge the battery to 80% approx. So less than 10kwh ( about 8kwh).

Minimal SOC at 110 kph is generally speaking 30%. Maximum SOC is 80%. Difference is 50% SOC. 50% times total capacity is 6 kWh. Bit OT, but still

Like I said my fuel trip computer shows 10lts/100ks in charge mode, ie charging battery and driving front wheels, but I do use 98 octane fuel (premium) if that makes a difference (hmm, have to try regular), at 110kph gps.

You mean "over a period of charing", not "over a period of charging and subsequently draining the battery again", right?

Then 10 l/100km @ 100 km/h gps seems very low, compared to my 11l/100km @ 100 km/h gps. I cannot imagine that fuel type could explain 10% less consumption at 10% more speed. If it does, I will start using premium right away.
- At what % SOC did you get to this value? In my previous post, I explained how (I believe that) instantaneous fuel consumption goes down when SOC increases.
- What kind of trip computer are you talking about? The one from the car itself, or an external one that connects to you OBDII port?

I appear to be using 2lts/100ks extra for charge mode ie increasing SOC, compared to save mode ( over time ) ie not increasing SOC.

So, you are saying, fuel consumption over a period of "engine on" is 2 l/100km more than over the full cycly? That totally makes sense. But it says noting about overall efficiency, as you would be comparing instantaneous fuel consumption with average fuel consumption and in a hybrid vehicle that doesn't make sense. Not saying you say it does

Mitsubishi Australia claims you will use 20% more fuel for charge mode. Perhaps that what they mean ie 10lts/100ks charge mode 8lts/100ks no charge mode ie 2/10 =20%, when they should have said 2/8 =25% (you there Anko?), and they are not considering the extra Ev range you get from the charge button.

Quite possible. Would be rather narrow sighted, though.

when they should have said 2/8 =25% (you there Anko?)

Haha. That would be the old VAT mistake: Price excluding VAT + VAT% equals price including VAT. But price including VAT - VAT% does not equal price excluding VAT. :lol:

 

[anko]

Hi Maby,

Perhaps on your next trip away you could try this technique ie being in Ev mode as much as possible especially if you know the slow sections for forward planning.

What's to lose?

Regards Trex.

Important to understand is that Maby is not so much aiming at max efficiency, but at maintaining sufficient SOC for climbing some hills he encounters on his trips. So, he is in a somewhat different discussion than some others. Allowing to drain the battery to optimise overall efficiency is not something he would gladly do. Did I get that right, Maby?

 

[anko]

Without Charge mode, the engine is intermittendly turned on and off automatically. When the engine is on, it drives the front wheels and some of the surplus power that is available is stored in the battery, allowing for the next period of engine off. This happens with SOC going up and down between 30 and 32% (normal mode) or with SOC going up and down between X and X+2% (save mode).

.

Perhaps this is where the "saving" comes from by not wasting small amounts of fuel stop/starting compared to a longer period of continuous running?

Indeed. That could explain some of it. But also, like I wrote two or three posts earlier, it might be that Trex is using Save mode at a higher (>50%) SOC, which IMHO will also lead to a reduced overall efficiency. We need to wait for his comments on that, I guess.

 

[anko]

Sorry, but the "1" in Save mode is exactly the same as a "1" in Charge mode.

How can you be so certain ?
Have you some docs ?

As a matter of fact, I do Next picture comes from Mitsu themselves.

It seems to confirm the statement from Maby that the car will not drop out of Charge mode when reaching 80%. It appears to behave as Save mode then.

Or some measures of intensity ?

That too. I have an OBDII scanner that reports instantaneous fuel consumption right from the OBDII port. It is very easy to toggle back and forth between Save and Charge mode and see that that has no effect whatsoever on the instantaneous fuel consumption. Or on the amount of power or torque produced. But that last bit doesn't really count as the last two parameters are derived from the instantaneous fuel consumption

Did you try Save mode and Charge mode at low speeds ?
If yes, did you hear the ICE (when it was in "1" on Save mode, of course) ?
No difference on your car ?

In mine yes !

So my conclusion is that the currents are different, at least at low speeds.
And why not at high speeds ? (it's just a question, anko ).

And they are good and valid questions Like I said before, this whole discussion applies only to speeds > 65 km/h (40 mph) when the car can engage in parallel mode. In series mode it is all very difficult to grasp.

My guesstimate is that even at low speeds, Save and Charge only differ in terms of the pattern of the 0's and 1's and not so much in the actual behaviour of the 0's and 1's. But it is very hard to substantiate.

Two additional remarks:
Do not use Charge when stopped at a traffic light. As said before, it will be relatively inefficient as you must first overcome the internal resistance of the engine (that otherwise would be stopped) before you can start charging. And next to that, the car will in many cases produce an ugly smell from the exhaust, and you will be in the middle of it

When the engine is started for the purpose of providing heat (i.e. battery not depleted and no use of Save or Charge mode), I am pretty sure it will NOT charge the battery. It will provide enough power to propel the car, but it will not provide additional power to enhance the SOC. You can see this for example when you are waiting for a traffic light: when the engine is already running for heating purposes the instantaneous fuel consumption does go up when you hit Charge. This means the engine was idling before. Also, when you get above 65 km/h (40 mph) the car will not engage in parallel mode, unless you hit Save or Charge. IMHO, this makes heating via the engine rather inefficient. I choose to engage Charge mode whenever it happens. Unless I am relatively close to the next charge point and have no need for the additional SOC.

 

[Grigou]

Many thanks for the document anko, it explains many things, can I post it in a french forum ?

And your explanations are convincing