Why charge the battery while driving?

[greendwarf]

[PPS: Possibly on a long trip on motor-way at constant speed .. clicking on save and having the car running in pure ICE mode ... you avoid "ageing" the battery due to the multiple partial charge cycle that would have happen otherwise .. but it is not going to be more fuel efficient using SAVE (unless you drive at the speed associated to the ICE RPM with highest efficiency)

Surely you are wrong on this - in Save mode the car DOES go through partial charge/discharge cycles, with the ICE cutting out to use up the excess EV generated to maintain the set battery level.

 

[anko]

[PPS: Possibly on a long trip on motor-way at constant speed .. clicking on save and having the car running in pure ICE mode ... you avoid "ageing" the battery due to the multiple partial charge cycle that would have happen otherwise .. but it is not going to be more fuel efficient using SAVE (unless you drive at the speed associated to the ICE RPM with highest efficiency)

Surely you are wrong on this - in Save mode the car DOES go through partial charge/discharge cycles, with the ICE cutting out to use up the excess EV generated to maintain the set battery level.

Indeed. Putting additional load on the engine makes it run more efficiently too. Exactly the same the car was designed to do and will do when you hit the (approx) 30% SOC mark, but then at a higher, user specified mark.

 

[jaapv]

Which it does with a depleted battery as well. Actually the "Charge" button is the one that reduces the number of charge cycles.

I read a few misconceptions above. The Charge and save buttons are not meant to optimize economy in constant driving condiotions, as Elm70 justly points out. Playing the car like a Hammond Organ makes no sense.

However as the car is not claivoyant, they are meant to allow the driver to modify the response of the car in anticipation of the upcoming use. One should keep in mind that the economy curves of EV use and petrol use cross at about 100 kph (depending on the relative prices).
This means that if one is driving on the motorway and anticipating a slower stretch to one's final destination, using "save" will be the best option.
Similar with "charge". If one knows that the motorway ahead will be hilly - not even mountainous- and that higher speeds are anticipated (like for instance running down the A7 form Kassel into Austria) it is bet to keep the car on "charge".

There are more situations to be postulated.
So the advice "Don't Touch" is too limited.

 

[elm70]

Indeed. Putting additional load on the engine makes it run more efficiently too. Exactly the same the car was designed to do and will do when you hit the (approx) 30% SOC mark, but then at a higher, user specified mark.

I still have to see the efficiency graph of the ICE .. so I don't know what make you to assume that 70kw output from the ICE is the optional in efficiency ?

Normally low rpm have higher efficiency ... around 2000 rpm is the "sweat" spot (ups on a diesel engine, on petrol I guess should be 2500rpm)

Ideally .. for motor way ... there should be a ICE button .. like to EV ... since at constant speed cycle charge/discharge is not good for ageing the battery .. as well ... charging the battery cost 15% in lost efficiency from the generator.

I believe above 80km/h ICE only mode is the most efficient way to make long distance ... and I would expect that if I press save at speed above 80km/h ... no battery is used, nor any charge should be done .. I would expect a pure ICE mode

As well .. at constant speed .. I also assume the car knows by itself .. what is the best to be done for optimize the fuel consumption .. that's way at the end .. I let the care do what it want to do ... I only car to don't exceed 60kw when ICE is off

 

[anko]

I still have to see the efficiency graph of the ICE .. so I don't know what make you to assume that 70kw output from the ICE is the optional in efficiency ?

Normally low rpm have higher efficiency ... around 2000 rpm is the "sweat" spot (ups on a diesel engine, on petrol I guess should be 2500rpm)

You read a lot of stuff that isn't there :evil: . I did not say 70 kW was optimal. I said adding more load on would be more optimal.

Imagine you driving 80 - 90 km/h in parallel mode, the ICE doing indeed 2500 rpm. Now, without charging the engine load is what, between 30 and 40%? Very inefficient. More heat than real kW output. With charging, the load can be kept at 75% (assuming your battery is sufficiently empty and thus willing to accept a decent charge current). What would be more efficient? An engine doing 2500 rpm at 40% or one doing 2500 rpm at 75%?

The PHEV tries very hard to maintain this 75% load, so I guess the engineers have worked out that this is most optimal (as it is for many ICEs). This is an important aspect of PHEV efficiency. Adding an ICE only button and using it would effectively turn your hybride into a very heavy normal car.

As well .. at constant speed .. I also assume the car knows by itself .. what is the best to be done for optimize the fuel consumption [/quote]Exactly! And hence the charge / discharge cycle.

 

[geoffshep69]

There are more situations to be postulated.
So the advice "Don't Touch" is too limited.

I agree.....but equally following a 'Don't Touch' approach will not result in a bad outcome. Whilst it may not be as optimal as using charge / save / paddles in an appropriate manner, for those who don't want to make the effort or are unsure of how to use the buttons, then 'Don't Touch' is a perfectly acceptable approach to adopt ?

 

[jaapv]

Sure, it is a good, strategy, but for optimal (sorry, Anko :twisted: ) use, the Save and Charge buttons are useful. As said, the car cannot know the conditions ahead.

 

[anko]

Sure, it is a good, strategy, but for optimal (sorry, Anko :twisted: ) use, the Save and Charge buttons are useful. As said, the car cannot know the conditions ahead.

Why "sorry, Anko"? I think I totally agree with you.

 

[elm70]

You read a lot of stuff that isn't there :evil: . I did not say 70 kW was optimal. I said adding more load on would be more optimal.

Imagine you driving 80 - 90 km/h in parallel mode, the ICE doing indeed 2500 rpm. Now, without charging the engine load is what, between 30 and 40%? Very inefficient. More heat than real kW output. With charging, the load can be kept at 75% (assuming your battery is sufficiently empty and thus willing to accept a decent charge current). What would be more efficient? An engine doing 2500 rpm at 40% or one doing 2500 rpm at 75%?

The PHEV tries very hard to maintain this 75% load, so I guess the engineers have worked out that this is most optimal (as it is for many ICEs). This is an important aspect of PHEV efficiency. Adding an ICE only button and using it would effectively turn your hybride into a very heavy normal car.

I did find this: http://ratherlightvehiclecompany.com/figefficiencycurveswdots455by326.gif

I was not aware the efficiency has a big impact based on the "load"

Actually above is a diesel engine .. but I believe the efficiency is similar

So ... in theory the best efficiency for the engine .. is going full power at 170km/h .. this should also avoid to "age" the battery with recharging it :mrgreen:

 

[jaapv]

The word gave you a bit of grief in another post

 

[anko]

I did find this: http://ratherlightvehiclecompany.com/figefficiencycurveswdots455by326.gif

I was not aware the efficiency has a big impact based on the "load"

I have been looking at graphs like this:

They specify Brake Specific Fuel Consumption, more or less how much mechanical energy you get out of every liter of fuel burned, and IMHO show better why you want to stay in an area of load / RPM.

So ... in theory the best efficiency for the engine .. is going full power at 170km/h .. this should also avoid to "age" the battery with recharging it :mrgreen:

I don't see how you come to that conclusion. As RPMs go up beyond the sweet spot, efficiency goes down again ....

 

[elm70]

So ... in theory the best efficiency for the engine .. is going full power at 170km/h .. this should also avoid to "age" the battery with recharging it :mrgreen:

I don't see how you come to that conclusion. As RPMs go up beyond the sweet spot, efficiency goes down again ....

I was speaking of engine efficiency (about car motion efficiency we all know that resistance/waste is proportional to the square or cube of the speed, so this has a mayor role in the practical car usage)

Anyhow ... per the graph I did link, it is quite clear, the delta of efficiency due to RPM is minor compared to delta of efficiency due to "load" .. at 100% load, efficiency is higher for any shown RPM at 75% load ... per the graph

Having full load continuously ... as far as I know happen only at the top speed .. or going uphill with full power ... as well .. full power acceleration is looking a more efficient way to accelerate .. compared to slowly accelerate

Adding the electric generator, in the equation , we should also consider the 10/15% waste converting motion "power" into electric "power" .. so at already high load, there should be no need to charge battery on the same time.

Anyhow .. the cycle approach between battery charging and EV motion ... I expect it make sense up to some "speed" (or power consumer for move the car) ... when the load needed for move forward is already high .. there is no advantage to charge the battery

This explain why I have seen my car at some speed running in pure ICE mode without charging the battery.

 

[anko]

I was speaking of engine efficiency (about car motion efficiency we all know that resistance/waste is proportional to the square or cube of the speed, so this has a mayor role in the practical car usage)

Why would you think I was not? But both graphs clearly show the engine is less efficient at high RPMs compared to mid range RPMs.

Anyhow ... per the graph I did link, it is quite clear, the delta of efficiency due to RPM is minor compared to delta of efficiency due to "load" .. at 100% load, efficiency is higher for any shown RPM at 75% load ... per the graph

So load has a bigger impact on efficiency than RPMs do. I grant you that. But it doesn't make the engine more efficient at 170 km/h.

Having full load continuously ... as far as I know happen only at the top speed .. or going uphill with full power ... as well .. full power acceleration is looking a more efficient way to accelerate .. compared to slowly accelerate

It seems that you consider "full load" to be the same as "max power output". To me, full load means (near) 100% throttle at a set number of RPMs. Not necessarily full throttle at max RPMs. With 100% load at 2500 RPM the engine is more efficient that it is with 100% at 4500 RPM.

Is it more efficiently to accelerate quickly? In a normal car maybe. In this car, the car will force the load up by charging the battery while accelerating slowly. Isn't that great? Again, as long as you maintain a low enough SOC. Otherwise, the battery will limit the max charge current and the engine cannot achieve 75% load.

Adding the electric generator, in the equation , we should also consider the 10/15% waste converting motion "power" into electric "power" .. so at already high load, there should be no need to charge battery on the same time.

Indeed, as soon as the load goes over 75%, the generator stops charging the battery. This is why caravan towing people have a hard time maintaining a decent level of SOC. The engine is capable enough, but very focussed on sticking to 75% load.

BTW: When the engine load is between 75% and 100%, the diagram shows no battery activity, but in reality a small amount of power is taken from the battery, to eliminate E-drag in both motors and the generator. Can be 4 kW or more. Above 100% engine load the E-motors will assist the ICE.

 

[Claymore]

But MMCS showing 4 miles EV range and zero mile total range - PATHETIC!

I think you are totally misinterpreting the '---' you see on the dash. Or does your car really show '0' as total range? I know mine doesn't.

You are correct Anko in that it doesn't show '0', it shows '---'. I assumed that (as in the EV range) when it showed that that meant less than 1 mile range remaining, which is as close to zero in terms of total range as I'd like to be.

What other interpretation of '___' is there?

EDIT: I've caught up with the other posts now but think that a sudden drop from 30miles range to '---' is completely stupid as a means of telling me to fill up when the klaxons and flashing lights in the centre console are already warning me I'm getting low on fuel. I only had 5 miles to go to my preferred filling station.

I think I'll do what I always did with a new company car in the days when I was lucky enough to get other people to buy my cars for me...put a gallon (5 litres roughly) can in the back and run it dry to see how far it goes after that display suddenly goes to '---', or zero as I like to call it. (I used to do a lot of fairly high speed trips to Scotland and back and didn't like wasting time en route stopping at filling stations if I didn't have to, so knowing what the fuel gauge was really telling me was useful).

Yes I know, prepare for the onslaught.....

JimB

 

[SolarBoy]

I think I'll do what I always did with a new company car in the days when I was lucky enough to get other people to buy my cars for me...put a gallon (5 litres roughly) can in the back and run it dry to see how far it goes after that display suddenly goes to '---', or zero as I like to call it. (I used to do a lot of fairly high speed trips to Scotland and back and didn't like wasting time en route stopping at filling stations if I didn't have to, so knowing what the fuel gauge was really telling me was useful).

I used to take this one further, if I had a car whose fuel gauge was on the pessimistic side I used to disassemble the dash, pull out the instrument console and bend the fuel gauge needle so it would be spot on accurate ...

 

[endsofinvention]

Fuel gauges are not 100% accurate, or at least the manufacturers don't want to have to ensure they are 100% accurate. If the "miles remaining" ticked down to zero, you'd get people who had 2 miles left then went up a steep hill (thus plummeting their MPG) and running out before they got to the petrol station 1 mile away, then complaining to the manufacturer that the "2 miles remaining" was wrong. If the "miles remaining" cuts out at ~30 miles it avoids people trying to eke out the last few miles and then being annoyed they ran out sooner than they expected.
Also, I believe that in some cases running an ICE to completely empty or near empty is bad for the engine (diesels get air in the injectors or something? And in petrol and diesel sucking all the sediment from the bottom of the tank is bad too). I am not an engineer though so that might be inaccurate.

 

[AndyInOz]

Just popped in to add an extra...

I use the "Charge" button to cause the engine to run more on longer (for me) trips.

I'm doing this specifically to cycle more fuel through the car.

This is because in my case, I quite regularly end up in the "Engine started to preserve fuel system" mode, because my usual commute doesn't use the engine at all.

The car does this until you add an extra 20 litres of petrol to the fuel tank.

So what has happened over time, is I gradually ended up with more petrol in the tank each time, until I couldn't get out of the "Engine started..." mode, because there was no room left in the fuel tank.

If you're using enough fuel, that you're regularly refilling the tank, you won't have this problem.

Andy

 

[Grigou]

Adding the electric generator, in the equation , we should also consider the 10/15% waste converting motion "power" into electric "power" .. so at already high load, there should be no need to charge battery on the same time.

Anyhow .. the cycle approach between battery charging and EV motion ... I expect it make sense up to some "speed" (or power consumer for move the car) ... when the load needed for move forward is already high .. there is no advantage to charge the battery

That's precisely the point !

At 120 kph GPS (flat road, no wind, and no towing of course) the car needs only about 25 kW (at least it's the approx. value displayed by the MMCS in EV mode). Not enough to obtain a correct ICE efficiency. IMHO adding 15 to 20 kW of power to charge the battery increases this efficiency dramatically.
I assume that the increase is greater than 15 %. If not, Mitsu engineers would not have decided to implement the charge-discharge cycle.

et voilà

PS : never forget this post http://www.myoutlanderphev.com/forum/viewtopic.php?p=13993#p13993 , and all the thread from the beginning http://www.myoutlanderphev.com/forum/viewtopic.php?f=10&t=1278

 

[PEDRO65]

Hello,
Just for crossing towns without pollution. You charge your battery before crossing towns. It's a real problem. In France last week, Paris, Lyon, Grenoble are restricted areas.
Pedro

 

[a09]

Lots of posts on this forum on those very subjects, so have a search around and you should find lots of detailed responses. But for what its worth, my take on it is:

- Charge should only be used if you are going to be able to use EV mode efficiently at your journeys end. So if you are driving on the motorway, but will be doing a significant amount of town/city driving at the end, or entering an EV zone, then you might want to use charge to give you battery range for that EV driving at the end.
- Using charge does result in higher fuel usage. the exact amount depends on speed / driving pattern. etc. but in general it is not an efficient mode of charging the battery, and usually the extra petrol you consume outweighs the extra EV range you will buy yourself.
- Using charge is far less efficient than charging from an electricity point so never use charge if you are driving home. Ideally you want to arrive home with empty battery, and then charge from mains.

- Main use of save is to alter the default usage pattern of electric versus petrol. Generally the battery is always used first, and once depleted you'll be running on petrol. If your journey starts off with 25 miles on the motorway, followed by 20 miles in the city, then you'll be doing the motorway miles on EV, and the city miles on petrol. This is the opposite of what you want from an efficiency point. Pressing save will retain your existing level of battery and force the car to run on petrol, so if you press save at the start of your journey you can then do the motorway on petrol, and retain your battery for the city, which is a far more efficient and clean method.
- Caveat to this is that I understand that pressing save with a near to full capacity battery is not entirely efficient, but others are far better placed than me to comment on that.

I'm sure you will get many more detailed replies which expand on this further, but thats my understanding of the basics.

This is the best answer I think make me clear about "SAVE" AND ""CHARG" key for newbie like me ...

Thank you!