The myth of inefficent petrol motor charging on the PHEV.

[anko]

Of course Save and Normal mode would do so too. If only the car would not intermittently switch to EV mode and use up the stored energy. Look at Trex' (or my ) diagram.

 

[Grigou]

The instantaneous charge current may be the same, but there is a massive difference in the effective charge current and power output otherwise Save or Normal mode would be taking the battery back up to full in an hour or so. You don't put upwards of 10kWh into the battery in an hour without increasing average power output.

10 kWh in an hour ?

It's just 10 kW (and ~ 30 A) during one hour. What else ?

 

[anko]

...
As why not the default mode? The Phev does not know our individual trip patterns.

Regards Trex.

Quite true. I guess that what I would prefer to see in place of the "Charge", "Save" and "Eco" buttons would be a set of usage style settings - things like "Suburban", "Motorway", "Long range", "Towing" - which select active power management strategies designed to suit those conditions selecting a power management policy that takes into account a combination of fuel economy, performance and battery life expectancy. I'm sure that it is possible to achieve the best results through a suitable combination of Charge and Save across your journey, but it really should not be necessary to be so actively involved in these decisions.

Ok. Towing means Save. Suburban means normal mode. That's easy. But what about the others: if we can decided what existing setting is correct for those conditions, simply use that existing setting. If we cannot decide, neither can the car. You are replace labels but not make the car understand what lays ahead ...

 

[maby]

...

Ok. Towing means Save. Suburban means normal mode. That's easy. But what about the others: if we can decided what existing setting is correct for those conditions, simply use that existing setting. If we cannot decide, neither can the car. You are replace labels but not make the car understand what lays ahead ...

I think those are probably oversimplifications - as plenty have pointed out, even on Save the battery will slowly discharge, so Towing probably requires a combination of Save with switches to Charge whenever the battery level gets below something like 50%. Also, you are thinking primarily in terms of minimising fuel consumption - what is the best strategy to arrive at a balance between fuel consumption, performance, battery life expectancy and, possibly, reducing engine wear? I'm not an expert in Lithium batteries - if you have to run for multiple days without plugging up, will leaving the battery flat all that time reduce its life expectancy? On our Prius, it would go into a very visible battery cycling mode every few days - running it almost flat, then fully recharging before letting it come back up to its nominal 50 or 60% resting charge level.

From the performance point of view, I would like a setting that increases the SOC floor and maintains that across power down and back up. I'm clearly not alone in that - gwatpe has gone to the trouble of designing and installing a small microcontroller in an effort to partly address this and others have expressed an interest in it.

 

[maby]

The instantaneous charge current may be the same, but there is a massive difference in the effective charge current and power output otherwise Save or Normal mode would be taking the battery back up to full in an hour or so. You don't put upwards of 10kWh into the battery in an hour without increasing average power output.

10 kWh in an hour ?

It's just 10 kW (and ~ 30 A) during one hour. What else ?

Sorry, don't understand what you are saying - 10kWh is a quantity of energy and 10kW is a quantity of power. You can charge 10kWh in many different ways - 10kW for an hour, 20kW for half an hour, 5kW for 2 hours, etc. etc. The standard 16A charging point puts 10kWh in in about 3 hours - so it is charging at around 3kW for 3 hours (plus a bit)

 

[anko]

The instantaneous charge current may be the same, but there is a massive difference in the effective charge current and power output otherwise Save or Normal mode would be taking the battery back up to full in an hour or so. You don't put upwards of 10kWh into the battery in an hour without increasing average power output.

10 kWh in an hour ?

It's just 10 kW (and ~ 30 A) during one hour. What else ?

Sorry, don't understand what you are saying - 10kWh is a quantity of energy and 10kW is a quantity of power. You can charge 10kWh in many different ways - 10kW for an hour, 20kW for half an hour, 5kW for 2 hours, etc. etc. The standard 16A charging point puts 10kWh in in about 3 hours - so it is charging at around 3kW for 3 hours (plus a bit)

Indeed. Charge rate (and thus efficiency) will drop as SOC gets higher (first step down at approx. 50%). The 10 kW would be an average over time.

 

[Grigou]

The instantaneous charge current may be the same, but there is a massive difference in the effective charge current and power output otherwise Save or Normal mode would be taking the battery back up to full in an hour or so. You don't put upwards of 10kWh into the battery in an hour without increasing average power output.

10 kWh in an hour ?

It's just 10 kW (and ~ 30 A) during one hour. What else ?

Sorry, don't understand what you are saying - 10kWh is a quantity of energy and 10kW is a quantity of power. You can charge 10kWh in many different ways - 10kW for an hour, 20kW for half an hour, 5kW for 2 hours, etc. etc. The standard 16A charging point puts 10kWh in in about 3 hours - so it is charging at around 3kW for 3 hours (plus a bit)

Right, but you forget that you was talking of "10 kWh in an hour" (and I underlined it in bold in your message)
So 10 kWh makes an average power of 10 kW during this hour. That's it, and what else (again) ?

 

[gwatpe]

I do not tow a caravan, but have often towed a loaded trailer. My experience is that the PHEV is not underpowered, but the electrics are unable to fully supply battery recharging needs to supplement battery use during periods of high power needs. As a result the battery is slowly depleted until PHEV driving performance is impeded, a result of the lack of additional power available from the battery when it is depleted. The optimized power algorithms for ICE efficiency dictate the power that is available for battery recharging while driving. I doubt that MMC would de-optimize the PHEV to give more recharging power. Presently when towing, the only way to maintain battery charge while driving is to reduce the driving speed. The power needs are reduced and hence more power can go towards battery recharging needs. This is to maintain a particular battery %SOC and not necessarily to fully recharge the battery.

We must remember that it is the unnecessary operation of the ICE in the non optimum fuel economy times that contributes to low efficiency. The battery recharging efficiency at low recharging power is actually higher than plugging into a high power station. There is a distinction we must make when referencing battery efficiency as opposed to petrol.

As has been referenced by others, I have made my own solution to overcome my particular opinions with power ON preferences settings. I have had no direct requests for my micro solution. The second PHEV driver with my mod in his car is very pleased and is looking forward to more driving holidays now.

I have recharged while stationery, but only during testing my PHEV when there were electrical problems and once to see how much fuel was needed to recharge the battery.

 

[anko]

About towing his boat, gwatpe wrote:

My experience is that the PHEV is not underpowered, but the electrics are unable to fully supply battery recharging needs to supplement battery use during periods of high power needs. As a result the battery is slowly depleted until PHEV driving performance is impeded, a result of the lack of additional power available from the battery when it is depleted. The optimized power algorithms for ICE efficiency dictate the power that is available for battery recharging while driving. I doubt that MMC would de-optimize the PHEV to give more recharging power.

Start with driving at a constant speed with an SOC <= 30% and wait for the engine to fire. With an OBD scanner you can note a specific instantaneous fuel consumption (don't need to explain this to you ). Now demand more power from there engine by pressing the gas pedal. You will see that the instantaneous fuel consumption will go up by a decent amount (maybe even 30 - 40%). Looking at the graph showing the engine characteristics (power / torque / sweet spot and such), this tells us the engine was operating well below the sweet spot before you started accelerating.

Therefor, I strongly believe it is the other way around: the maximum charge current dictates the maximum engine output, and with that how close we can get to the sweet spot. IMHO, this is confirmed by the fact that the instantaneous fuel consumption goes down with increasing SOC. And consequently, so does the engine efficiency. Apparently, to protect the battery, the charge current is reduced as the SOC goes up. Something we know from normal charging from the grid.

While driving solo at a constant speed we stay well below the sweet spot. Strangely enough, when we start accelerating, the cars first response is not to increase the engine output (and take the opportunity to get closer to the sweet spot), but to reduce the charge current, leaving more power for propulsion. Only once the charge current is reduced to 0 (blue arrow dimmed out), the output of the engine is increased and we get closer to the sweet spot. But by that time, charging has come to a full stop.

Now I could imagine that "temporarily making more power available for propulsion by reducing charge current" has preference over "temporarily making more power available for propulsion by increasing engine output", for various reasons, like more efficiency, more comfortable, better controllable or what not. I don't know. But when it gets to "constantly making more power available for propulsion", that should be done by increasing engine output and not by reducing charge current. And this is why I believe we should have a towing mode that chooses to increase power output, rather than reduce charge current as a response to increased power demand. This would enable the car to keep recharging the battery longer, even when under somewhat higher load.

I did a complete topic on this. Guess I am repeating myself .

 

[gwatpe]

I suppose that if the PHEV was not primarily designed as a short range electric vehicle we might have some alternative options.

Unless we have access to the design team, we will rely on interpreting graphs and data, that may be in error. I am waiting for a MUT3 to become available so I can get some first hand data on my PHEV.

Now that my PHEV is no longer able to flatten the battery as a startup option, and I have more control of the battery usage, the car works well as a hybrid. I have spent another day driving and included some stops in traffic. I just turned OFF SAVE mode for a bit in these times. towards the end of my trip I just turned OFF SAVE again to reduce the battery to below half when I got home. I had many stops with power OFF, and at any of these I could have forgotten to press a button. PHEV powered ON in the stored SAVE mode, and at the end of the day, I had plenty of battery left to use up on the last leg.

All during the day, the PHEV operated in parallel and series hybrid, with some EV when I turned SAVE OFF. overall economy was under 7L/100km. about 3/4 of the battery was used over the day and this improves petrol economy. My last car, a v6 sedan would have used 10L/100km, so the hybrid systems are helping reduce petrol consumption in an even bigger car.

 

[Kristian]

I have enjoyed this debate and the very illustrative graph! But I have a question. If you use the Charge button form SOC bottum to top you should gain a 52 km EV range and for that you use 3.1 l petrol. This gives 6.15 l/100 km and that seems better than many reports on fuels usage runing tha car after the EV range. Even if the calculation is optimistic I have seen people using 7-8 l by letting the PHEV do its own stuff. Opinions?
K
PS Just ordered a 5hs for use here in Norway, so no experience yet.

 

[maby]

I have enjoyed this debate and the very illustrative graph! But I have a question. If you use the Charge button form SOC bottum to top you should gain a 52 km EV range and for that you use 3.1 l petrol. This gives 6.15 l/100 km and that seems better than many reports on fuels usage runing tha car after the EV range. Even if the calculation is optimistic I have seen people using 7-8 l by letting the PHEV do its own stuff. Opinions?
K
PS Just ordered a 5hs for use here in Norway, so no experience yet.

I can't think in terms of litres/100km but it's reported that a full charge consumes something over 3 litres - about three quarters of a gallon. If you reckon on getting something close to 40mpg, that gives you around 30 miles range on petrol. It will not give you a 100% charge - which seems to realistically give you an EV range of perhaps 25 miles - so I guess that using petrol to charge the battery is around 20% less cost effective than burning it to drive the car directly.

 

[Kristian]

6.15 l/100 km is almost 46 mpg
It seems you think I will get only 25 staute miles using 3 liter which I think is 33 mpg (8.6 l/100 km), this is not so great but not extreemly bad either. I think the diesel Outlander uses 6.7 l/100 km.
Perhaps using the Charge mode for ex half or 2/3 way up would be more efficient?
What do you get beyond EV range using your "mode"?

 

[Kristian]

and btw running the engine for driving the axel (paralell) is one thing, but I was thinking about comparing with the serial mode thay way the car does it without interference. The only difference to Charge would be the SOC range used perhaps?

 

[Kim]

I belive the 3.x litres from bottom to stop charging are @ around 80% soc.
That would give us 40 km electric and equal a little more than 8l/100km

I was looking for Trex's original post with this experiment, but I couldn't find it.

Hope he can clear it up?!

 

[Trex]

I belive the 3.x litres from bottom to stop charging are @ around 80% soc.
That would give us 40 km electric and equal a little more than 8l/100km

I was looking for Trex's original post with this experiment, but I couldn't find it.

Hope he can clear it up?!

Hi,

Sorry been away but here it is :

http://www.myoutlanderphev.com/forum/viewtopic.php?f=10&t=1265

An 80% charge is about right according Mitsubishi Australia and if you look in that topic it went from 1 bar already lit (when my Phev is "empty" 1 bar is showing) to 14 bars so 13 bars charged up compared to 16 bars when full gives 81.25% according to my calcs. Or maybe it should be 13 bars charged up to only 15 bars usable on my Phev which is 86.66% or should it be 14 bars out of 16 bars which give 87.5%. :roll: :lol: This graph shows about 85%.



Regards Trex.

Mitsubishi image from anko.

 

[Kristian]

Again an interesting curve. Is the reason that the car chooses to zigzag close to the turtel redline because it is the most efficient SOC range, or because it would be stupid to arrive without having used up most of the charge? Perhaps both?

I guess one could test if the Charge mode is inefficient by comparing the fuel consumption for the same drive by letting the car do its ting, or making a large zigzag by using the charge button repetitively. Has that been done?

If one can trust the range calculation one could also determine the inefficcience, if any, by running the Charge, and see if total range goes down much or at all. But the calculations seems to depend on many factors and might not be accurate, if we are talking 10% accuracy is needed.

I have to agree that my inclination also has been to think that the charge button would waste energy by transforming energy an extra time, but it can not be too bad since non-plug-in hybrids has been a viable option.

This aside. How important is it to have some extra SOC for lets say a mountain climb? Experiences?

 

[anko]

Again an interesting curve. Is the reason that the car chooses to zigzag close to the turtel redline because it is the most efficient SOC range, or because it would be stupid to arrive without having used up most of the charge? Perhaps both?

I think it is both. If it would zigzag around for example 50%, people would bitch about the fact that the car had used only 50% of the battery capacity they had payed for. If it was above 50%, the engine efficiency would go down as the charge current was reduced to protect the battery.

Some people play with Save mode to come by: use Save mode to zigzag around a higher SOC as long as they are far away from home and then after a while, when they get close to home (or the next charge point), disengage Save mode to allow the battery to drain to 26 - 30% SOC.

I still don't understand that. Under normal driving conditions 30% is more than enough to keep you out of the Turtle zone. For more demanding conditions (towing, climbing), you can use Charge mode to optimize your SOC "in advance and during". When your driving conditions are such that the battery would be drained well below 30%, I don't see how Save mode could save the day.

 

[gwatpe]

Some people play with Save mode to come by: use Save mode to zigzag around a higher SOC as long as they are far away from home and then after a while, when they get close to home (or the next charge point), disengage Save mode to allow the battery to drain to 26 - 30% SOC.

I still don't understand that. Under normal driving conditions 30% is more than enough to keep you out of the Turtle zone. For more demanding conditions (towing, climbing), you can use Charge mode to optimize your SOC "in advance and during". When your driving conditions are such that the battery would be drained well below 30%, I don't see how Save mode could save the day.

Normal conditions vary from driver to driver. I doubt that most drivers can measure any substantial difference in their cars efficiency based on how much energy is in the battery.

I have now operated my PHEV with the SAVE button mod for over a week with over 500km driven, without plugging in to recharge the battery or using CHARGE mode to recharge. I have however turned OFF save at the top of a long steep decline and back ON at the bottom a few times. I did not empty the tank and still have half a battery capacity remaining. The PHEV was powered ON and OFF multiple times per day. The battery was slowly depleted over the week, mainly due to the loss of a set point for the SAVE mode on power OFF. Was able to pick up a couple of bars on the downhill stretches and this helped a bit over the week. REGEN at 30kW for 4km beats using brake pads for the same effect. The highway speed operation has the ICE supplying most of the driving power directly to the wheels in parallel hybrid mode, with periods of the battery absorbing surplus or supplying additional energy to meet driving load requirements. My typical drives have hills, and 2-3 battery bars may be used in addition to the ICE on the way up some, which is replaced on flatter sections when in SAVE mode.

Towing power requirements are very subjective and individuals will need to find the best mix of modes for their needs.

If plug recharging is unavailable, I am expecting my PHEV to need partial manual CHARGEs every 1000km or so of petrol motor driving. I am not expecting this to impact much on overall petrol economy. Having my PHEV preferentially power ON in SAVE mode has reduced the number of times I have had to use CHARGE mode to bring the battery level up to allow my PHEV to climb the 4km steep uphill section on my drive home from the city. [At 100kph, my PHEV uses approx 15L/100km petrol and 20-30kW from the battery for 4km of uphill driving and REGENS 20-30kW and 0L/100km on the way downhill] This type of drive highlights some of the efficiencies of higher power needs with electric help, compared to flat ground driving with around 7-8L/100km at the same speeds. Average petrol consumption up and back is about the same as level driving. With better instrumentation we would know for sure. The apparent high efficiency of the PHEV electrics as demonstrated by up and down hill measurements is evidence that the PHEV can make and store electrical energy for effective use later with low losses.

 

[FLYER34]

Some [most ?] people..... use Save mode to zigzag around a higher SOC as long as they are far away from home and then after a while, when they get close to... charge point, disengage Save mode to allow the battery to drain to 26 - 30% SOC.

I still don't understand that. Under normal driving conditions 30% is more than enough to keep you out of the Turtle zone....

3 very good reasons for people to use "Save" mode this way :
- only the driver knows what is the planned trip (as long as we do not get "intelligent" GPS - OBC link) ;
- OK, 30 % charge is enough for "normal driving conditions", BUT, imho, EV is better suited for city driving : using "Save" (or "Charge") mode at high speed, out of town, avoids having the ICE running when stopped at trafic lights due to low SOC ;
- driving with minimal SOC, puts you at risk of high ICE stress in case of an unexpected power demand (ie : long, steep climb).

Waiting to be within EV range of the next charge point before letting the SOC drop below, say, 50 % seems good politcs.