I use charge mode for better fuel consumption.

[Trex]

Hi Anko,

You asked if I use the Save button, no hardly ever(in early days for experimentation), on longer trips out of grid ev range I only press the Charge button.

You asked why go to 80% fully charged before arriving at my destination. I sometimes will be staying in a area for a few days that will be only 60kph zones and I want max ev range. Remember I get my best fuel savings by ev mode in the slower sections. Its all about the planning and using my GPs. I normally only go to 50% because I am too impatient.

You stated max capacity is actually only 6kwh, my meter on my grid charger says I put in approximately 10kwh to charge from empty, and yes I know there will be losses but until someone quantifies those losses, that is the figure I will use. Charge mode will only charge to approximately 80% so I call that 8kwh.

I also call the hv battery empty when the petrol motor starts even when I know there is still some SOC in reserve. I said I owned a Prius in another post and it was exactly the same ie the hv battery never fully discharged or charged for longevity and what I would call emergency use.

As for your 11 to my 10lts at 100 to my 110kph that is a instantaneous reading after a reset on the cars own fuel computer when the hv battery is empty. Sorry I have been calling it a trip computer, which is what they were called in my younger days. I have never seen an 11lts/100ks except on my diesel Mitsubishi Pajero which is even bigger and heavier than the Phev.

Regards Trex.

 

[Trex]

Hi again Anko,

That graph you supplied in the above post is a gem of a find. I read the figures about the lower SOC of the hv battery in some of your previous posts in other discussions but that graph shows it all so beautifully. Do you have more?

In my opinion that graph and any other official Mitsubishi graphs should be placed in a sticky discussion at the top of the technical discussions section. Thoughts any one ?

Regards Trex.

 

[Trex]

Hi Titan,

I hope someone gives it a try because I am really starting to think it is just my Phev and nobody really believes I can get this result ie getting better fuel consumption using the charge button and staying in ev mode as much as possible.

This technique is not something I've invented, like I said before I had a Prius before the Phev and, in the Prius, you could drive around all day getting 5lts/100ks ,urban or freeway just holding down the accelerator. But if you lift your foot off the accelerator (in the Prius), once up to speed, the petrol motor would stop and you would go into ev mode, and then reapplied your foot on the accelerator (still in the Prius) and kept it below the midpoint on a power meter on the dash, you would stay in ev mode and Toyota actually stated you should do this to get the best fuel consumption.

The trouble with the Prius was the hv battery could only output just enough amps, or power, to just hold 60kph (our local urban speed limits) on the flats so this technique would only work in the urban areas and yes it would definitely give better fuel consumption ie keep that petrol motor off as much as possible. I used to see 3 to 3.5lts/100ks keeping up with traffic where other people on the Prius forum could even get less by doing what they called a pulse and glide but I will not bore you with that story.

So you would be traveling in ev mode, in the Prius, and yes the hv battery would discharge and yes the petrol motor would restart and drive the front wheels and recharge the hv battery so you could do it all over again ie go back to ev mode. But the fuel consumption stayed lower than just holding down the accelerator pedal and leaving the petrol motor running but it was definitely a lot more hassle in the Prius, than just pressing the charge button on the Phev every now and again.

I been reading this forum and the other English speaking Phev forum , and all I have seen about the charge button in discussions is do not press it unless building SOC for climbing hills, towing or maybe pollution free zones. Well I press it to get better fuel consumption on trips away but maybe it only works on my Phev.

Regards Trex.

 

[anko]

You asked if I use the Save button, no hardly ever(in early days for experimentation), on longer trips out of grid ev range I only press the Charge button.

I see. In your opening post, you wrote:

From experimenting I have found that even at 115 kph indicated (110 kph gps ) on the freeway with the car in parallel mode I get 8lts/100ks in save mode against 7.5lts/100ks in charge mode.

This is why I was so 'focussed' on finding explanations on why and when Save could be less efficient for you I thought that it might be explainable if you were hitting Save mode ay 80%.

You asked why go to 80% fully charged before arriving at my destination. I sometimes will be staying in a area for a few days that will be only 60kph zones and I want max ev range. Remember I get my best fuel savings by ev mode in the slower sections. Its all about the planning and using my GPs. I normally only go to 50% because I am too impatient.

I understand the why. But effectively, by driving around at 80% SOC you disable the HV capabilities of the vehicle (lowering it's efficiency) for the purpose of increasing its efficiency later on. I wonder if that will pay off. At least, try to stay as long a possible below 50% and try to recover the rest at the end of the fast part of your trip.

You stated max capacity is actually only 6kwh, my meter on my grid charger says I put in approximately 10kwh to charge from empty, and yes I know there will be losses but until someone quantifies those losses, that is the figure I will use. Charge mode will only charge to approximately 80% so I call that 8 kwh.

I don't think I said is that max capacity is 6 kWh. What I meant to say is that the difference in amount of energy stored in the battery when depleted (30-ish%) and when charged while driving (80%) is about 6 kWh. Your 10 kWh measured at the grid is needed to go from 30-ish% to 100%. So, it bridges a gap of 70%. To go from 30% to 80% you only need to bridge a gap of 50%. Your 10 kWh / 70% * 50% = 7,14 kWh. A little bit more than 6 kW indeed. But the OBC (On Board Charger) that converts your 230 volt AC (or whatever you guys have down there) to 300 volt DC by it self has a loss of 4.5% (Mitsu figure ). That sets you back to 6,8 kW. Some losses that you see while charging from the grid will also occur during Charge mode as well, so even though the amount of energy added to the battery will be approx. 6 kWh max, the amount of energy needed to do so will indeed be little bit more than 6 kWh.

As for your 11 to my 10lts at 100 to my 110kph that is a instantaneous reading after a reset on the cars own fuel computer when the hv battery is empty. Sorry I have been calling it a trip computer, which is what they were called in my younger days. I have never seen an 11lts/100ks except on my diesel Mitsubishi Pajero which is even bigger and heavier than the Phev.

While driving 100 km/h:

I am using 11.1 liters/100km:

I am having fun while having these discussions. Hope you are too. Cheers.

 

[anko]

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

And your explanations are convincing

Thanks. And can't see why not.

 

[anko]

Hi Titan,

I hope someone gives it a try because I am really starting to think it is just my Phev and nobody really believes I can get this result ie getting better fuel consumption using the charge button and staying in ev mode as much as possible.

This technique is not something I've invented, like I said before, I had a Prius before the Phev, and you could drive around all day getting 5lts/100ks ,urban or freeway just holding down the accelerator. But if you lift your foot off the accelerator, once up to speed, the petrol motor would stop and you would go into ev mode, and then reapplied your foot on the accelerator and kept it below the midpoint on a power meter on the dash, you would stay in ev mode and Toyota actually stated you should do this to get the best fuel consumption.

The trouble was the hv battery could only output just enough amps, or power, to just hold 60kph (our local urban speed limits) on the flats so this technique would only work in the urban areas and yes it would definitely give better fuel consumption ie keep that petrol motor off as much as possible. I used to see 3 to 3.5lts/100ks keeping up with traffic where other people on the Prius forum could even get less by doing what they called a pulse and glide but I will not bore you with that story.

So you would be traveling in ev mode, in the Prius, and yes the hv battery would discharge and yes the petrol motor would restart and drive the front wheels and recharge the hv battery so you could do it all over again ie go back to ev mode. But the fuel consumption stayed lower than just holding down the accelerator pedal and leaving the petrol motor running but it was definitely a lot more hassle than just pressing the charge button on the Phev every now and again.

I been reading this forum and the other English speaking Phev forum , and all I have seen about the charge button in discussions is do not press it unless building SOC for climbing hills, towing or maybe pollution free zones. Well I press it to get better fuel consumption on trips away but maybe it only works on my Phev.

Regards Trex.

Although I am not Titan, let me respond to this:

I do believe that (as long as you don't overdue it by driving around with a almost fully charged battery most of the time) you may get a better cross-trip average consumption by "charging the battery on fast parts of the trip, allowing for more EV driving during the slower parts of the trip". But from your opening post, (at least to me) it appeared as if your conclusions was that instantaneous consumption was better in Charge mode than it was on Save mode. And that is IMHO very doubtful unless you tested with different SOC's or so.

But after 15 months and 40.000 km at the wheel of my PHEV, I would be very very surprised if there was a mechanism or strategy involved like the one you describe for the Prius. If, at any given speed, the car can do EV, it will do EV. You do not have to convince it to do so by temporarily lifting the gas pedal. If people think differently, I would like to know very much.

There may be one other strategy that I try to experiment with every now and then. Above approx. 50 km/h, the SOC will go as low as approx. 30%. Below that speed the SOC will be allowed to go a bit lower. So, if you arrive at the city limit (reduce your speed) just before reaching 30% SOC, you can do a couple of km's in the city on EV. But if you hit 30% SOC, just before arriving the city limit, the engine will start and it will not necessarily stop when you then gradually lower your speed at the city limit. At that time, it appears to help to slow down more brusk (for example by using regen breaking) until the engine stops and then slowly speed up again. Of course staying under 50 km/h.

Not very useful with AUS city speed limits, I am afraid.

 

[maby]

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?

You did - I'm looking for a simple strategy for getting a reasonably performant car that is easy to drive for prolonged periods away from a mains supply. I was hoping that selecting Charge on a reasonably full battery would give me a "set-and-forget" function.

When you talk about Charge mode only taking the battery up to 80% charge, are you talking about 80% on the instrument panel gauge, or the 80% that we believe a full bar on the gauge represents? I ask because my PHEV in Charge mode seems to be trying for a full gauge! I've seen it take the battery to just one bar off full on the Energy Flow display, and it still kept the engine running with the car stationary - and this was in a warm car, so not for heating.

Having also been a Prius owner, I think the primary problem with a PHEV running as a hybrid on long journeys is that the hysteresis loop of the power controller is much smaller than that of the Prius. Both cars have a target state of charge, but the PHEV tries to keep the battery within a few percent of that at all times. The Prius firmware will allow the SOC to oscillate up and down by a much larger amount - allowing it to maintain a good working SOC without wasting petrol since it can take more advantage of varying driving conditions. Trex's strategy playing with the Charge button is really just implementing that large hysteresis loop manually.

 

[anko]

My line of thinking:

First bar = 30%
All 16 bars = 100%

So, every extra bar is 70 / 15 = approx 4.67%.

Charge mode should then stop at approx. 12 bars. But I cannot remember checking this for myself.

I don't really see the issue with the loop being short. Looking at the diagram I posted earlier, it seems the PHEV lets the SOC oscillate between 26 and 32%, giving a bandwidth of 6% and an average of 29%. If the oscillation bandwidth was doubled from 6% to 12% this would average out at 32%. As small gain. You could be lucky and end up at the bottom of the hill with 38% SOC, but you could also be unlucky and end up at the bottom of the hill with 26% SOC. Like now. What you 'are supposed to do' when you care for SOC, is press the Save button at for example 40-ish %. Then the average SOC will be 43% and never less than 40%.

And let's not forget, the PHEV does allow a lower SOC. Either because you are driving slower (city speeds) or when you are demanding power at lower SOC.

 

[Grigou]

Charge mode should then stop at approx. 12 bars. But I cannot remember checking this for myself.

Hi anko

Having tried just one time 4 months ago I remember 14 bars, occasionally. It's more ofen 13 bars (fluctuates between 13 and 14 if you stay in Charge mode).

But not completely sure : it could be 12-13

 

[Trex]

Hi Anko,

Yes you have a image showing you get a 11.1lts/100ks at 100kps and I will assume you checked by getting a instantaneous reading by doing a reset on the cars own fuel computer at the same time as your reading with DashCommand otherwise we might be comparing the old apples and oranges. I only use the Phevs own fuel computer.

You state: I do believe that (as long as you don't overdue it by driving around with a almost fully charged battery most of the time) you may get a better cross-trip average consumption by "charging the battery on fast parts of the trip, allowing for more EV driving during the slower parts of the trip".

Is that a slight admission I may be bringing you over to the dark side? Do not worry I will not be driving with a full battery most of time, I want to be in ev mode as much as possible.

I think I have proven that in my Phev that I can keep the petrol engine off longer and be in ev mode more, by using a strategy that Toyota recommended for the Prius, than if I left the Phev to its own control or just pressed the save button to use the grid supplied charge in low speed areas which on longer trips would be soon gone (Unless you can grid charge while away which here in Australia is very hard to do ).

Regards Trex.

ps Yes I do enjoy having these technical discussions about the Phev. Cheers.

 

[anko]

Next occasion where I can do 100 km/h on cc, I will check.

I have no doubt whatsoever, the Prius would support your strategy. Never driven one

Cheers,

Anko

 

[maby]

Hi Titan,

I hope someone gives it a try because I am really starting to think it is just my Phev and nobody really believes I can get this result ie getting better fuel consumption using the charge button and staying in ev mode as much as possible.

...
Regards Trex.

Now that I understand what you are doing, I believe you. You are manually manipulating the power flow cycle to implement an enlarged hysteresis loop - allowing the state of charge to oscillate above and below your selected level by quite a large margin and over a relatively long period.

 

[gwatpe]

The deliberate cycling of the battery over a large %SOC range will impact on the cyclic life of the battery. The very small saving of petrol would need to be weighed against the cost of replacing the battery at an earlier time due to total cycles sustained in that time.

My driving conditions are similar to Trex in Australia.

If the battery was U/S within the warranty period, caused by exceeding the battery expected cycles in that time, then the exercise would work for me. I suspect that the battery would last through warranty and the owner would then have battery replacement to consider shortly after.

Mitsubishi would possibly have factored an average of 1 cycle per day, so in 5 years 1500-2000 total cycles. The Lithium batteries are expected 3-5000 cycles for 80%DOD, so we should see 5-10 years service life.

If you save 2.5L/ tank this comes to about AU$3-4. probably $5/week, so maybe $250/year. The battery costs about $10000 to replace. Don't think cycling the battery to save a few Litres of fuel is cost effective.

PS I saw earlier a comment that the CHARGE stays on until manually turned OFF. It goes OFF automatically when the PHEV considers that the petrol tank is empty and there is some battery charge left.

 

[anko]

Next occasion where I can do 100 km/h on cc, I will check.

Didn't manage 100 km/h but did manage 90 and 80. At 90 I got 10.9 both on the scanner and in the dashboard. At 80 I got 10.3.

The fact that I had just a little bit more consumption in the past at 100 km/h (11,1) is IMHO related to the fact that the faster you drive, the less you will charge. At 130 km/h I thinpk there is hardly any charging at all.

 

[Trex]

Hi anko,

Thanks for checking DashCommand compared to Phev's own computer. We now know we comparing apples to apples. Do you use a bluetooth obd2 adapter with DashCommand and do you mind if I ask you which one and has it been reliable or have any problems with it ie Dashcommand or bluetooth obd2 adapter. I used to use Scangauge but hated the display and ended up giving it to my son. Perhaps this should be more appropriately asked in a separate discussion to allow other members to discuss other products as well.


After a good look at this whole discussion, especially that sawtooth line on the graph you provided anko, yes I agree the Phev is trying to go into ev mode whenever it can( I can here your cheering from here). Because basically it is charging up the hv battery as soon as the petrol motor starts in any mode, serial or parallel, and all I am doing is reducing the number of start stops of the petrol motor on the freeway and keeping the car out of serial mode charging in slower areas which I think everyone would agree is less efficient (than parallel mode charging).

I think that last point should be repeated. I am keeping the car out of serial mode charging. Which in my case shows up as a noticeable fuel savings.

You would have to admit anko using my strategy on the freeway would save a small amount of energy not starting the petrol motor as much, and I am taking the voltage of the hv battery to a higher level than the Phev would do under its own control which in itself may give better efficiency. I am not a battery expert. I do know a battery does take a charge better when the SOC is lower, ie resistance is lower, so I can see your point anko about not taking the SOC too high for better efficiency.

Regards Trex.

 

[gwatpe]

The discussions seem to hinge on a small economy gain at the expense of increased deep cycling of the difficult to replace main traction battery. The traction battery must be difficult and expensive to replace as Mitsubishi chose to replace my 6 month old PHEV instead of repairing the battery.

If the PHEV is driven predominantly as a petrol car, then driving it in a way to reduce petrol consumption does seem feasible, however, I have personal experience of a PHEV with low EV range and this impacted much more on the returned petrol economy of the PHEV. A loss of 10km of electric range, typically results in an additional 1L of petrol burned for a drive that is just beyond the battery range, say 60km. In this example, twice as much petrol is typically needed for the same drive.

I would not be encouraging a driving style that deliberately increased the cycling of the traction battery.

If petrol became much more expensive, and the PHEV had to be driven on predominantly ICE petrol energy, and the car was leased, then a case for increased cycling of the traction battery could be made.

 

[Trex]

Hi Maby,

You stated : Now that I understand what you are doing, I believe you. You are manually manipulating the power flow cycle to implement an enlarged hysteresis loop - allowing the state of charge to oscillate above and below your selected level by quite a large margin and over a relatively long period.

Hysteresis, or what I like to think of as a lagging behind in the changing of a state of a input- output system (forming a loop when plotted), may be helping my highway fuel consumption. Is that what you mean ie by having less "lag" in the changing state of charging- discharging. I am not sure if it is. I am only see a small saving on the freeway and as I said before this may not worth worrying about.

But I think we can all agree that serial mode charging is not as efficient as parallel mode charging otherwise why have it, ie parallel mode, and I think we can safely say this car is trying to enhance the SOC every time the petrol motor runs so it can go into ev mode later, see anko's graph, dependent on load (like a bloody big hill or towing a trailer).

Regards Trex.

 

[Trex]

Gday gwatpe,

This car is cycling the hv battery no matter what we do once the petrol motor starts . Are we sure that lots of little ones are better than 1 bigger one . I think, here in Australia, heat is going to be the biggest cause of loss of capacity in ev car batteries but at least our Phevs have a active cooling system, unlike the leaf, but that only runs when it is switched on. Left parked in the sun on 40 degrees C plus days will probably kill our batteries first IMO. I know we should avoid this but does that mean we should stop using our cars in summer?

How do you know the batteries cost about $10,000.00 ?

Regards Trex

 

[gwatpe]

The cheapest Lithium cells work out around $400 per kWh. The Mitsubishi cells are part of a pack with at least 10 computers and cell balancing componentry as well as high voltage protection systems as well as mechanical containment and the included cooling system. These will not be the cheapest cells available either.

Second hand replacement battery for a Prius is about $3500. This is a fraction of the capacity of the PHEV. I believe it is 1.8kWh compared to at least 12kWh in the PHEV.

I can only personally compare that the value of 6 months depreciation was less than the cost of replacing the battery. Price of replacement was mentioned on another thread as well.

The PHEV does not have the rapid exchange pack like the Model "S" Tesla.

The longer highway trips to the city, My PHEV is operated in predominantly SAVE mode. Yes there will be some mini cycles, but at the highway limit of 100kph, It amounts to a very small number, maybe 3-4 per hour of approx 1 battery bar. If I forget to engage SAVE for the return journey, then CHARGE is used like you use to bring the battery back to about 50%, as there is a very long uphill section and the car works best to climb this in parallel hybrid in at least SAVE mode with ICE and up to 60kW electric support to maintain the 100kph.

I have checked my replacement PHEV today, and I was able to still drive EV only, 50km of mixed road types including town and country, including some decent climbs and decents on a return journey. The hot driving conditions experienced recently have had no noticeable effect on the battery only range. Only 4 more summers to see out the warranty. I suspect NW WA and the Pilbara will impact more than summer. Driving with a flat frozen battery might impact the life expectancy more than heat. Will just have to wait for feedback from EU forum members. Where I live, the temp averages 15-20C for most of the year, with a few tens of hours a year above 30C. I am not too concerned about the effect of heat on the battery.

The cells in my OFF grid home energy system, supplied directly from the Chinese manufacturer were $500 / kWh. Service life now 5 years, and cycled <50% once per day on average show no capacity loss impacting system operation. The LFP chemistry in the PHEV battery does not have the cycle life of the LYP chemistry in my house setup, but the PHEV has enough protection systems to protect against over and under charge, but unfortunately it is the driver who manages the overall battery cycles.

 

[anko]

Thanks for checking DashCommand compared to Phev's own computer. We now know we comparing apples to apples. Do you use a bluetooth obd2 adapter with DashCommand and do you mind if I ask you which one and has it been reliable or have any problems with it ie Dashcommand or bluetooth obd2 adapter. I used to use Scangauge but hated the display and ended up giving it to my son. Perhaps this should be more appropriately asked in a separate discussion to allow other members to discuss other products as well.

I use and ELM327 WiFi as WiFi is what the iPhone needs. Works reasonably well, as long as I have a profile installed on my phone that prevents it from spontaneously connecting to the REMOTExxxxxx WiFi. Otherwise, it will have a hard time connecting or will loose the connection quite frequently. With the profile, it is alright.