Fuel consumption in relation to Drive battery levels.

[Trex]

Hi folks,

This will be the last test I will do for awhile. I hope it helps everyone.

I picked the flattest area around here ( and it is very flat across the river valley here) on the dual lane freeway (in each direction) that runs past our small city. It is made up of approx. 12kms of 100kph zone and 10km of 110kph zone. I picked that stretch for its easy turn around at each end as well as being flat.

So the test consisted of driving in one direction then the other followed by a quick turnaround at each end. Traffic was light. I sat on 105kph . I used cruise control the whole time except at each end when I was turning around.

Now this is the same as I did the other night but more scientifically ie I ran both directions fully before taking measurements to allow for any wind or elevation changes. I have not, I repeat not done that before.

Here are the results.

Press save button straight at start with full battery. 15 bars showing (out 16 ) on MMCS when finished test. 7.8L/100k Petrol motor never stopped. B5 15kw

Press Save at 13 bars. 14 bars showing (out 16 ) on MMCS when finished test. 7.8L/100k Petrol motor never stopped. B5 25kw

Press Save at 11 bars. 12 bars showing (out 16 ) on MMCS when finished test. 7.4L/100k Petrol motor stopped a couple of times B5 37kw

Press Save at 8 bars. 9 bars showing (out 16 ) on MMCS when finished test. 7.4L/100k Petrol motor stopped a couple of times. B5 37kw

Press Save at 7 bars. 8 bars showing (out 16 ) on MMCS when finished test. 7.4L/100k Petrol motor stopped a couple of times. B5 37kw

Press Save at 6 bars. 7 bars showing (out 16 ) on MMCS when finished test. 7.4L/100k Petrol motor stopped a couple of times. B5 37kw

Press Save at 4 bars. 5 bars showing (out 16 ) on MMCS when finished test. 7.2L/100k Petrol motor stopped like a proper hybrid. B5 37kw

At 1 bars (normal mode). 1 bars showing (out 16 ) on MMCS when finished test. 7.2L/100k Petrol motor stopped like a proper hybrid. B5 37kw

Note No AC or heater on.

Note The B5 amounts are Regen that I could get at the end of the runs with the paddles set to B5 when turning around.

Note Where I said the petrol motor never stopped it only stopped at each end of the run where I turned around.

Note Where the Petrol motor stopped I read it at the same point of the hybrid cycle.

Note I could not do this test more scientifically without putting it on a dyno.

Note I have just lost 6 hrs out of my life.

Note There are no more Notes. :lol:

Regards Trex.

Ok I will bring this in from over at the technical section from sometime ago that may help you achieve lower fuel consumption.
It does for me.

It probably belongs just as much over here anyway.

Notice that max regen is not available till under 14 bars.

 

[ChrisMiller]

Thanks for doing all that work, Trex. As regen has the capability of delivering similar charging rates to the 'high-power' recharging points widely available in the UK (bot not in Oz, as I understand it), it may well be limited to charging up to ~85% as they are. I think this may be because delivering lots of kW to a battery that's nearly charged generates lots of heat, but am happy to be corrected by those with better technical knowledge.

 

[Trex]

Thanks for doing all that work, Trex. As regen has the capability of delivering similar charging rates to the 'high-power' recharging points widely available in the UK (bot not in Oz, as I understand it), it may well be limited to charging up to ~85% as they are. I think this may be because delivering lots of kW to a battery that's nearly charged generates lots of heat, but am happy to be corrected by those with better technical knowledge.

Yes I also think they are doing this to protect the battery.

Charge mode on my Phev will also not go above about 85% for the same reason IMO. ie the fast part of charge mode. Others have reported it gradually increases above that while driving but when stationary the petrol motor stops on my Phev.

 

[user 816]

Thanks for doing all that work, Trex. As regen has the capability of delivering similar charging rates to the 'high-power' recharging points widely available in the UK (bot not in Oz, as I understand it), it may well be limited to charging up to ~85% as they are. I think this may be because delivering lots of kW to a battery that's nearly charged generates lots of heat, but am happy to be corrected by those with better technical knowledge.

Yes I also think they are doing this to protect the battery.

Charge mode on my Phev will also not go above about 85% for the same reason IMO. ie the fast part of charge mode. Others have reported it gradually increases above that while driving but when stationary the petrol motor stops on my Phev.

Although if you plug into a UK rapid charger with a certain level of charge already in the battery, it will charge you to 100% I have experienced this myself but not sure what the level must be before it does this.

I had considered using the charger to 80%, then hooking up again straight away to see if I could then get to 100% but I have not been brave enough to try it... yet

 

[ChrisMiller]

Given the occasional reports of cars being 'bricked' at fast chargers, I think that would be a very brave experiment, Bob! Are you relying on the 'bars' for your assessment of battery charge, or have you more sophisticated tools? From reading the technical documentation on this site, I think the level of charge is misrepresented on the car's display, as when it shows 'empty' there is still ~13% charge retained (necessary so the car can be started). I wonder if something similar happens when it shows 'full'.

I've noticed when charging from the standard house supply and monitoring using the phone app, the "time to complete" is never less than 1 hour. So if I start from empty at 1800, it will show an ETA of (say) 2330. If I check at 2315, the app will probably show a full set of bars, but still charging and a further hour to complete. If I check again 10 minutes later, it will show charging complete. Having worked with laptops a lot, I guess this may just reflect the charging characteristics of a Li-ion battery.

 

[maby]

Given the occasional reports of cars being 'bricked' at fast chargers, I think that would be a very brave experiment, Bob! Are you relying on the 'bars' for your assessment of battery charge, or have you more sophisticated tools? From reading the technical documentation on this site, I think the level of charge is misrepresented on the car's display, as when it shows 'empty' there is still ~13% charge retained (necessary so the car can be started). I wonder if something similar happens when it shows 'full'.

I've noticed when charging from the standard house supply and monitoring using the phone app, the "time to complete" is never less than 1 hour. So if I start from empty at 1800, it will show an ETA of (say) 2330. If I check at 2315, the app will probably show a full set of bars, but still charging and a further hour to complete. If I check again 10 minutes later, it will show charging complete. Having worked with laptops a lot, I guess this may just reflect the charging characteristics of a Li-ion battery.

It's not really a misrepresentation - it is a conscious design decision. The life expectancy of the average lithium battery in a phone or laptop is just a few years - maybe five at a pinch, but they will have lost a lot of capacity by then. We accept that because they cost just a few pounds to replace and the marketing cycle on phones or laptops is such that we'll probably be thinking of replacing them by then. A car, on the other hand, is expected to have a lifetime of at least ten years before it needs significant maintenance - the designers of hybrids address this by overspecifying the battery by a fair amount.

 

[user 816]

Given the occasional reports of cars being 'bricked' at fast chargers, I think that would be a very brave experiment, Bob! Are you relying on the 'bars' for your assessment of battery charge, or have you more sophisticated tools? From reading the technical documentation on this site, I think the level of charge is misrepresented on the car's display, as when it shows 'empty' there is still ~13% charge retained (necessary so the car can be started). I wonder if something similar happens when it shows 'full'.

I've noticed when charging from the standard house supply and monitoring using the phone app, the "time to complete" is never less than 1 hour. So if I start from empty at 1800, it will show an ETA of (say) 2330. If I check at 2315, the app will probably show a full set of bars, but still charging and a further hour to complete. If I check again 10 minutes later, it will show charging complete. Having worked with laptops a lot, I guess this may just reflect the charging characteristics of a Li-ion battery.

Well it is a lease/company car so if it goes wrong doing a 'normal' charging procedure its their problem not mine..

I was going by the charger display as well as the bars. I think the first time I tried a rapid charge I had maybe 50 to 70% already but not sure (1st practise run!). Car bars and charger went to 100%, every other time I have rapid charged from near zero (or at least 20% in reality we know) and the bars and charger only go to 80%

 

[ChrisMiller]

Well it is a lease/company car so if it goes wrong doing a 'normal' charging procedure its their problem not mine..

Same here, but I still wouldn't want to be stuck at a motorway services waiting for a tow truck

 

[Claymore]

................From reading the technical documentation on this site, I think the level of charge is misrepresented on the car's display, as when it shows 'empty' there is still ~13% charge retained (necessary so the car can be started)....

When I was taking delivery of my car the dealer told me that when the battery shows 'empty' there is still a certain amount left (over and above what is required to avoid individual cell's voltages falling below the level at which they can't be safely recharged) and the reason for that is to minimize the number of drivers (he seemed the thing company drivers were the highest proportion of miscreants but I couldn't possibly comment) who got stranded by running out of battery and motion lotion.

He said that Mitsu had previously told them not to tell anyone because that would make the aforementioned miscreants even more likely to take the car to the wire, but current instructions were to inform customers that this invisible reserve existed.

I can't for the life of me remember how far he said the car might go and in any event;

1. I'm not brave enough to put it to the test
2. In the light of others' recent experiences of quoting what Mitsubishi have told them I have to immediately distance myself from the suggestion!

:roll:

JimB

 

[greendwarf]

I can't for the life of me remember how far he said the car might go and in any event;

1. I'm not brave enough to put it to the test
2. In the light of others' recent experiences of quoting what Mitsubishi have told them I have to immediately distance myself from the suggestion!

:roll:

JimB

I seem to remember gwatpe took the bullet for us on this in 2014?

 

[HHL]

I can't for the life of me remember how far he said the car might go and in any event;

1. I'm not brave enough to put it to the test
2. In the light of others' recent experiences of quoting what Mitsubishi have told them I have to immediately distance myself from the suggestion!

:roll:

JimB

I seem to remember gwatpe took the bullet for us on this in 2014?

The technical manual explains quite nicely what the car does. It will not discharge the battery below 26%, this is where the engine starts when you have driven in EV mode until no bars show. It will then run in hybrid mode as well as charging the battery back up to around 30% (one bar showing).

In some circumstances when high power is requested beyond what the engine/generator can supply, the battery can go below 26% and this is where the "turtle" mode starts.

If you continue with high power demand in "turtle" mode, the car will shut down the aircon and heater at 22% charge and finally limit the power available at 17%.

If the engine then runs out of fuel, the car will stop when the battery is down to 13%. This is enough to restart the engine after refuelling.

So, under normal conditions the battery will be somewhere between 26 and 30% when you commence charging with no or 1 bar showing.

One really has try quite hard to get the battery below 26% in normal use.

 

[anko]

I am pretty sure it is like this:

At 30% the battery indicator shows 1 segment. Below 30%, no segments are shown.

At speeds below 65 km/h, the car tries to maintain an SOC between 26 and 28 %.
At speeds above 65 km/h, the car tries to maintain an SOC between 31 and 32,5%.

When you keep demanding more power than the ICE can deliver at low SOC, the SOC may go lower.
At 22% the heater and A/C are killed.
At 20% the Limited Driving Capability warning will light up (Turtle mode).
At 13% the car comes to a halt when the petrol tank is empty.

I know from personal experience (towing my 1500 kg caravan into a strong head wind) that SOC can be between 21 and 25% for a very long time (100+ km) without seeing the Turtle warning.

 

[Neverfuel]

Thanks for doing all that work, Trex. As regen has the capability of delivering similar charging rates to the 'high-power' recharging points widely available in the UK (bot not in Oz, as I understand it), it may well be limited to charging up to ~85% as they are. I think this may be because delivering lots of kW to a battery that's nearly charged generates lots of heat, but am happy to be corrected by those with better technical knowledge.

Yes I also think they are doing this to protect the battery.

Charge mode on my Phev will also not go above about 85% for the same reason IMO. ie the fast part of charge mode. Others have reported it gradually increases above that while driving but when stationary the petrol motor stops on my Phev.

Interesting - I can't get anything above 85% in charge mode! but you have AUS version and Gwatpe!s model can charge to 100%. Is there a big difference in your models?

 

[Trex]

Thanks for doing all that work, Trex. As regen has the capability of delivering similar charging rates to the 'high-power' recharging points widely available in the UK (bot not in Oz, as I understand it), it may well be limited to charging up to ~85% as they are. I think this may be because delivering lots of kW to a battery that's nearly charged generates lots of heat, but am happy to be corrected by those with better technical knowledge.

Yes I also think they are doing this to protect the battery.

Charge mode on my Phev will also not go above about 85% for the same reason IMO. ie the fast part of charge mode. Others have reported it gradually increases above that while driving but when stationary the petrol motor stops on my Phev.

Interesting - I can't get anything above 85% in charge mode! but you have AUS version and Gwatpe!s model can charge to 100%. Is there a big difference in your models?

Hey Neverfuel,
I think I remember it was someone over there that also stated it went higher while driving..

 

[maby]

...

Hey Neverfuel,
I think I remember it was someone over there that also stated it went higher while driving..

Me, for a start - I've seen my PHEV working hard to turn the last block on the SOC meter blue - it doesn't succeed typically because the rate of charge into an almost full battery is so low, but mine certainly tries. (and it is not only while driving - if I press the Charge button with a nearly full battery, it will happily sit at the lights stationary with the engine running and the graphic display showing charging current going into the battery)

 

[Trex]

...

Hey Neverfuel,
I think I remember it was someone over there that also stated it went higher while driving..

Me, for a start - I've seen my PHEV working hard to turn the last block on the SOC meter blue - it doesn't succeed typically because the rate of charge into an almost full battery is so low, but mine certainly tries. (and it is not only while driving - if I press the Charge button with a nearly full battery, it will happily sit at the lights stationary with the engine running and the graphic display showing charging current going into the battery)

Above 85% or above 14 out of 16 bars on the MMCS the petrol motor keeps running in your Phev when in charge mode and when stationary? :shock:
Are you positive?

It is easy to check and have asked you to do so. Just drop the SOC down to say 12 bars and press the charge button and go have a cup of tea or whatever. The petrol engine will automatically stop at 14 bars or does on mine. Mind you it hits 14 bars then runs for awhile and then shuts down. It never gets to 15 bars.

Can someone else check?

 

[gwatpe]

The way the CHARGE button works seems to be related to being driven or not.

The first week I had a PHEV #641, in 2014, I tried the CHARGE when stationary. Only managed the 14 bars.

Later on my AUS road trip in a different PHEV #121, tested at 100kph and also 110kph. Both times my PHEV filled the battery up to all bars. took about 150km both times.

When the battery was empty, 0 bars, in CHARGE mode, petrol consumption was about 14L/100km and PHEV recharging was about 1km added to battery range for every 2km driven. Seemed very good. As the battery bars went up, needed more km driven for each additional km to shown battery range. Petrol consumption went down slowly as well.

This data was gathered as a side effect of almost running out of petrol between stops. battery had to be run out to allow the last of the petrol to be used to get to a refuel stop. No battery corded recharging available.

High speed driving with a loaded PHEV and an empty battery does not work for me. PHEV works better for me with at least 1/4 to 1/2 a battery capacity left shown. I do now try and avoid driving with a full battery on a trip. This is possibly a reason my trips are returning marginally higher petrol economy in recent times compared to last year.

Running my PHEV in empty battery first mode to save a few % on petrol economy is not a big enough incentive to counter the series hybrid operation that my PHEV predominantly operates in when the battery is empty. I have found a sustainable solution on a longer, mainly petrol trip with multiple stops between refuels with sticky SAVE operation. I can select when to allow the battery to be drawn down to about half when it suits me. I can then re-engage SAVE, and then stop as many times I like. Sticky SAVE takes care of preserving the battery level between stops. Over a day, the battery level does drop with multiple stops. This may slowly improve the petrol economy. Maintaining Parallel Hybrid operation may save as much petrol as running with an empty battery and Series Hybrid operation, but without the disconnected engine noise I seem to hear, that I find irritating, associated with series hybrid operation.

 

[Neverfuel]

Thanks for doing all that work, Trex. As regen has the capability of delivering similar charging rates to the 'high-power' recharging points widely available in the UK (bot not in Oz, as I understand it), it may well be limited to charging up to ~85% as they are. I think this may be because delivering lots of kW to a battery that's nearly charged generates lots of heat, but am happy to be corrected by those with better technical knowledge.

Yes I also think they are doing this to protect the battery.

Charge mode on my Phev will also not go above about 85% for the same reason IMO. ie the fast part of charge mode. Others have reported it gradually increases above that while driving but when stationary the petrol motor stops on my Phev.

Although if you plug into a UK rapid charger with a certain level of charge already in the battery, it will charge you to 100% I have experienced this myself but not sure what the level must be before it does this.

I had considered using the charger to 80%, then hooking up again straight away to see if I could then get to 100% but I have not been brave enough to try it... yet

I don't know whether it will EVENTUALLY get to 100% on a rapid charger as I have only ever got it to 95%. If you are over 60% or so it will charge past 80% where it usually stops and go to 95% before cutting out. The last bit takes ages though as it dramatically reduces the charge rate. It may be that if you were to start the charge cycle again it would fill up the remainder - but I'm not going to be the one that tries that one.

 

[anko]

High speed driving with a loaded PHEV and an empty battery does not work for me. PHEV works better for me with at least 1/4 to 1/2 a battery capacity left shown. I do now try and avoid driving with a full battery on a trip. This is possibly a reason my trips are returning marginally higher petrol economy in recent times compared to last year.

Running my PHEV in empty battery first mode to save a few % on petrol economy is not a big enough incentive to counter the series hybrid operation that my PHEV predominantly operates in when the battery is empty. I have found a sustainable solution on a longer, mainly petrol trip with multiple stops between refuels with sticky SAVE operation. I can select when to allow the battery to be drawn down to about half when it suits me.

I have always suggested that fuel economy would be better when the battery was not too full. But I have also said that, startend with aan empty batterij the first step down in charge current would be Sheen you reach approx 50% SOC (65% on the gauge). I have even posted graphs to back that up. And I have reasoned that approx 50% real SOC would also be the point at which you have the first step down in fuel economy. This also matches Trex' table quit nicely.

So, with this new strategy you should be perfectly fine, from my perspective

 

[anko]

When the battery was empty, 0 bars, in CHARGE mode, petrol consumption was about 14L/100km and PHEV recharging was about 1km added to battery range for every 2km driven. Seemed very good. As the battery bars went up, needed more km driven for each additional km to shown battery range. Petrol consumption went down slowly as well.

This data was gathered as a side effect of almost running out of petrol between stops. battery had to be run out to allow the last of the petrol to be used to get to a refuel stop. No battery corded recharging available.

So, when the fuel level dropped you were first forced to drive in EV mode and only when the battery was also depleted, it would use the last bit of fuel, right? I assume you saw this data (14 l/100 km), only after filling up the petrol tank again? I am just asking, as mine turns into a normal, but very heavy petrol car when both the battery and the fuel tank are almost empty. The engine will provide the power for driving but nothing more. Fuel consumption is directly related to throttle position. No charging whatsoever. And so on. One difference with a normal car: the PHEV will maintain serial mode, even above 65 km/h.

At what speed was this? Compared to my own readings at 100 km/h gps, your burn rate (14 l/100 km) and recharge rate (1 per 2) seem rather high. I was seeing numbers more in the line of 11 or 12 l and 1:3. As I have written repeatedly, coincidentally even in the last two days , I have noticed that engine load in parallel mode never exceeds 75% on mine (unless driving conditions demand so) and with 75% load at 100 km/h fuel consumption is definitely lower than 14 l/100 km.

What you wrote suggests the engine did not do this only briefly to get SOC back at an acceptable level, but for a longer period of time, during which SOC was raised well above 1 bar. Is this correct?

One possible cause for (part of) these differences could be speed. At a lower speed the recharge rate would be probably better, if only because at a lower speed you need less electrical power per km in EV mode. At a lower speed fuel rate (in terms of l/h) will be less as RPM goes down. If speed goes down faster than fuel rate in terms of l/h, then fuel rate in terms of l/100 km automatically goes up. But if this is the case, I don't know.

An other reason could be that your engine goes higher than 75% load, even when there is no need to do so under the current driving conditions. Did you ever monitored the %Engine Load on Torque Pro while the engine was running in Save or Charge mode? It would seriously interest me for two reasons:
- The picture that Grigou posted yesterday, showing torque curved and all suggested that the sweet spot supits higher that at 75%. But perhaps I take that picture to serious / literally and it is only meant to explain a mechanism.
- If mine would do 80 or 85% load instead of 75%, it would be become a much beter tow car.

I think I must try to get some readings:

- speed
- fuel rate
- charge current
- engine load