Charging the battery from the engine only

[greendwarf]

Still, the topic was about efficiency of charing, not speed of charing.

Charing? Must have overheated the ICE when running it at max revs to produce 50kw :lol:

 

[greendwarf]

If you press "Save" while the battery is partially charged, you get a similar effect with the battery oscillating around a higher charge level. Only the "Charge" button will actively increase the state of charge.

In theory yes. but in practice I noticed that on a long drive through France in Save the battery level on the dash gradually increased (not much over several hours but definitely rose)

 

[maby]

If you press "Save" while the battery is partially charged, you get a similar effect with the battery oscillating around a higher charge level. Only the "Charge" button will actively increase the state of charge.

In theory yes. but in practice I noticed that on a long drive through France in Save the battery level on the dash gradually increased (not much over several hours but definitely rose)

I think that is more a case of the behaviour of the vehicle in parallel hybrid mode than the setting of the "Save" button. Once it gets into parallel mode, the engine speed is directly linked to road speed and there can be some spare power output that can be directed to the battery. In Normal mode, it seems to alternate between periods of ICE operation and periods of EV that use up the charge gained during the ICE operation. In Save mode, the balance seems to be a bit tilted - more ICE and less EV, so the SOC drifts up - but I think it is just a coding error, not an active attempt to charge.

 

[anko]

We are arguing around terminology here - I observe the same and would not describe it as "charging" - what you are describing is what I called "pass through"

Like I said, if you insist in not calling it “charging”, be my guest. We don’t have to agree on everything . But tell me, when you run Save mode or Charge mode, for a longer period of time, does’t the energy also ‘just pass through’? Unless you intend to take the SOC home with you, that is ….

Basically, all this discussion seems to be about is to make clear to TS that running in Normal mode will not increase his SOC the way Charge mode will do over time. I think he got that by now.

- the engine is effectively generating the power requirements of the motors with the battery functioning as a buffer.

As you did yesterday, when you described it as “buffering for fluctuations in power demand”, you make it sound as if we have one of those cars where they downsized from a V8 to a V6 and added an E-motor and a small battery to step in when the V6 couldn’t handle it. But then you are selling the car short. It is generating a surplus of power, not just to have a buffer for fluctuations in power demand, but also to allow for periods of EV driving following periods of hybrid driving. This goes way further than just buffering for fluctuations in power demand and highly adds to the efficiency of the vehicle.

For a variety of reasons, I've been driving on a flat battery for the last few days without plugging in - the SOC meter has never gone above one bar and only occasionally gone down to zero bars - that is not charging in the sense that the OP was questioning here.

He was also asking about the most cost effective way of driving when no external charging was available. Well, in general just using Normal mode and let the car do it’s own thing is just that. So, I think understanding how Normal mode works is very relevant.

On a related subject that we have discussed here, I took my wife to the station this morning and she remarked that the engine was really racing - flat battery plus moderate acceleration results in high engine revs - and this was driving at 20 or 30mph on flat suburban roads, not racing up the motorway.

Mine doesn’t do that. At least, no more than a decent CVT would do and no more than it would do when running in Charge or Save mode (well half of the time). And yes, you could prevent this by maintaining higher SOC. But the question is how far you can go with this before you negatively impact efficiency.

BTW: Could it be that, before reaching the flat road, you had done some climbing and exhausted the battery further than the low water mark? And that the system was still recovering from that?

 

[anko]

If you press "Save" while the battery is partially charged, you get a similar effect with the battery oscillating around a higher charge level. Only the "Charge" button will actively increase the state of charge.

In theory yes. but in practice I noticed that on a long drive through France in Save the battery level on the dash gradually increased (not much over several hours but definitely rose)

I think that is more a case of the behaviour of the vehicle in parallel hybrid mode than the setting of the "Save" button. Once it gets into parallel mode, the engine speed is directly linked to road speed and there can be some spare power output that can be directed to the battery. In Normal mode, it seems to alternate between periods of ICE operation and periods of EV that use up the charge gained during the ICE operation. In Save mode, the balance seems to be a bit tilted - more ICE and less EV, so the SOC drifts up - but I think it is just a coding error, not an active attempt to charge.

Based on my latest observations that I posted in another thread, I think it is somewhat different:

- When driving faster than 120 km/h, the engine is running all the time but still SOC does it's normal cycle. Where at 100 km/h the engine load alternates between 75% (parallel hybrid mode) and 0% (EV mode), at 122 km/h it alternates between 75% and approx. 55%. Possible explanation: E-power is used to eliminate electromagnetic drag in both E-motors and the generator. This power is, although not shown on the energy flow diagram, taken from the battery. At these times, the engine needs to run at approx. 55% load to propel the car. When SOC drops below the known threshold, the engine starts to work a bit harder in order to enhance SOC again. And so on.

So, I don't think this would cause SOC to drift up. But we all know that when you ask a lot of power, SOC can go down, despite the use of Save mode: The car performs the normal cycle. Then you take some extra power, but the car keeps performing the normal cycle, without compensating for the power loss. Perhaps, the same could happen in a reverse manner in an environment with moderate hills: On the way up, the engine works a bit harder to compensate for the extra power demand. So, no need for taking extra power from the battery. But on the way down, regen could enhance SOC. But the car will continue to perform the normal cycle. But at a higher SOC level. How is that for a thought?

 

[maby]

.....

BTW: Could it be that, before reaching the flat road, you had done some climbing and exhausted the battery further than the low water mark? And that the system was still recovering from that?

No climbing - we left the house in an ambient temperature of 16 degrees and the climate control set to 21. The route from our house to the station is completely flat (apart from a couple of speed humps) and probably just over a mile. The battery had not been charged for a couple of days and was showing one bar - the engine kicked in - which was to be expected - but revving quite high and unpleasantly high on moderate throttle opening. It is certainly not the way I like my car to behave - and very reminiscent of a Prius with a flat battery.

 

[anko]

Any change of hooking up an OBDII scanner to see actual RPM figures?

 

[Grigou]

If you press "Save" while the battery is partially charged, you get a similar effect with the battery oscillating around a higher charge level. Only the "Charge" button will actively increase the state of charge.

In theory yes. but in practice I noticed that on a long drive through France in Save the battery level on the dash gradually increased (not much over several hours but definitely rose)

Your battery was happy to be in France I presume :mrgreen:

 

[Grigou]

We are arguing around terminology here - I observe the same and would not describe it as "charging" - what you are describing is what I called "pass through"

Like I said, if you insist in not calling it “charging”, be my guest. We don’t have to agree on everything . But tell me, when you run Save mode or Charge mode, for a longer period of time, does’t the energy also ‘just pass through’? Unless you intend to take the SOC home with you, that is ….

Basically, all this discussion seems to be about is to make clear to TS that running in Normal mode will not increase his SOC the way Charge mode will do over time. I think he got that by now.

- the engine is effectively generating the power requirements of the motors with the battery functioning as a buffer.

As you did yesterday, when you described it as “buffering for fluctuations in power demand”, you make it sound as if we have one of those cars where they downsized from a V8 to a V6 and added an E-motor and a small battery to step in when the V6 couldn’t handle it. But then you are selling the car short. It is generating a surplus of power, not just to have a buffer for fluctuations in power demand, but also to allow for periods of EV driving following periods of hybrid driving. This goes way further than just buffering for fluctuations in power demand and highly adds to the efficiency of the vehicle.

For a variety of reasons, I've been driving on a flat battery for the last few days without plugging in - the SOC meter has never gone above one bar and only occasionally gone down to zero bars - that is not charging in the sense that the OP was questioning here.

He was also asking about the most cost effective way of driving when no external charging was available. Well, in general just using Normal mode and let the car do it’s own thing is just that. So, I think understanding how Normal mode works is very relevant.

On a related subject that we have discussed here, I took my wife to the station this morning and she remarked that the engine was really racing - flat battery plus moderate acceleration results in high engine revs - and this was driving at 20 or 30mph on flat suburban roads, not racing up the motorway.

Mine doesn’t do that. At least, no more than a decent CVT would do and no more than it would do when running in Charge or Save mode (well half of the time). And yes, you could prevent this by maintaining higher SOC. But the question is how far you can go with this before you negatively impact efficiency.

BTW: Could it be that, before reaching the flat road, you had done some climbing and exhausted the battery further than the low water mark? And that the system was still recovering from that?

anko, I entirely agree with you

It seems that our 2 continental cars have not the same behaviour as some islander cars

 

[gwatpe]

There may be programming differences between LHD and RHD PHEV's. My AUS shipped PHEV is unpleasant to drive when the battery is showing empty on the gauge.

As we get more familiar with our PHEV, we are better able to judge how we manage the battery on any drive. I prefer to drive most of the time with a fullish battery, with SAVE mode and then empty the battery on the final 20-30km to get to my next recharge with a close to empty battery. Other drivers let the car do its own thing and for most of a longer drive have an emptyish battery.

I am expecting that the battery in my PHEV will have a longer life, with a possible slight increase in petrol consumption as a result.

I am sure that the OP will not routinely recharge the battery from the ICE only, and on any longer drives beyond the EV range, will either be very diligent with pushing buttons for SAVE and NORMAL operations to arrive at a recharge location with an empty battery, or just let the PHEV do its own thing and not be too concerned about ICE operations needed to achieve it. It has been certainly proven that generally, there is no need to worry about recharging the battery while driving. Some special circumstances like towing, or long steep climbs may necessitate either saving some battery for these times, or using the ICE to bring the stored battery level up to drive these conditions in a way the driver wants to.

I soon realized that I was not diligent enough to push the buttons at the right time, every time I drove my PHEV on a longer drive, so I resolved the problem with my sticky SAVE mod. I have been caught out a few times with ICE operation for a few seconds I had not intended, on an intended EV only drive.

 

[anko]

My AUS shipped PHEV is unpleasant to drive when the battery is showing empty on the gauge.

Like you said earlier, it would be great to have a decent OBDII app with logging and all, so we can compare data from cars from various markets. Then we can see whether it boils down to differences in expectations or programming. Who knows ...

 

[maby]

There may be programming differences between LHD and RHD PHEV's. My AUS shipped PHEV is unpleasant to drive when the battery is showing empty on the gauge.

...

I see no reason to believe that they are different - I think it is more likely the case that the drivers are, on average, different. I'm from the group that have gone through the last twenty-odd years on large cars with even larger engines - big V8 normally aspirated petrol lumps and four litre turbo charged diesels - an engine doing more than about 2000RPM sets my teeth on edge. In normal operation, I want my PHEV to be ticking over around 2000 RPM, the engine difficult to hear and the bulk of the acceleration coming out of the battery which then gets topped back up quite quickly once you get up to cruising speed. My UK programmed PHEV does not behave that way on a flat battery - the revs go up - and can go up pretty high in response to a wide throttle opening with a flat battery.

Given your location, I guess that you've also grown up on big trucks with very large engines that rarely break sweat!

 

[anko]

an engine doing more than about 2000RPM sets my teeth on edge.

Poor you. As 4500 RPM is 170 km/h, you will be restricted to 75 km/h. Unless you stay within EV range of your home. Then it is 120 km/h

 

[maby]

an engine doing more than about 2000RPM sets my teeth on edge.

Poor you. As 4500 RPM is 170 km/h, you will be restricted to 75 km/h. Unless you stay within EV range of your home. Then it is 120 km/h

I live in England - our speed limit is 112km/h. In practice, I seldom drive over 60mph - which comes out at about 2500rpm on your figures - still reasonably quiet at that speed.

 

[maby]

OK - update based on experiences this afternoon...

I wonder if we have different perceptions of the car because its behaviour is not particularly deterministic and we simply do not see the same car a lot of the time. I just went shopping - with my still flat battery and it started out behaving itself very well - running in a mixed mode with periods of pure EV and periods on ICE but the revs kept down to the point where I had to look at the power flow to be sure if the engine was running or not. This carried on for a couple of miles to the shop, but traffic was fairly heavy and I could not go very fast or accelerate much.

I came out of the supermarket and started out for home - car still behaving the same - then the traffic cleared and I accelerated hard off the lights - and everything changed. The engine fired up and revved hard although acceleration was not very good - and that became the pattern for the rest of my trip home - engine running all the time, revving quite high even when stopped and when I accelerated, the revs went up high, but the acceleration was poor - I had the left hand gauge round to the three o/clock position with the engine running fast and the car doing 20mph. The battery gauge never dropped below one bar.

I've seen this before, but never analysed it so carefully. It was the same as I saw this morning when my wife was asking why the engine was racing. If you never accelerate hard from stationary or close to stationary with a flat battery, you may never see it but once you trip it over to that state, it seems to stay like it for a long time.

 

[anko]

This is very odd. The power meter (left dial) shows how much power is used for driving alone. Regardless of whether it comes from the engine or battery. Power consumption by the aircon, or power generated by the engine to recharge the battery or such does not show. As a matter of fact, power used to eliminate E-drag in the E-motors and / or generator does not show either. Regen'd power does show, as this is related to driving. Anyway, if the meter is in the 3 o'clock position, that would mean you are using 120 kW (approx. 160 bhp) for driving (assuming the dial goes the same way as on the continent :mrgreen: )

Now, here is the strong bit: at 20 MPH (about 32 km/h, right) you are obviously running in serial mode. But both E-motors together can output just little over 60 kW at that speed (28 km/h is 60 kW, 56 km/h is 120 kW). If they were outputting more power at that speed, it would mean max torque of the E-motors was exceeded. Not possible, IMHO.

So, if you put in 120 kW for driving and at the same time get out no more than 60 and a bit kW, where is the rest going? At 20 MPH, the E-motors should already be rather efficient.

At 20 MPH, both the battery and the engine should, by themselves, be able to provide almost as much energy as needed to get the best possible acceleration. And at that speed, that should be fairly good. Above that speed, you need the combination of battery and engine to get maximum push. So, as far as I'm concerned, neither a malfunction of the battery nor a malfunction of the generator could, by itself explain why acceleration would be poor at that speed.

Other point of view: if you floor it with a depleted battery, SOC will drop below the low water mark. Once you ease off, the car will try to re-establish (what it considers) a decent SOC asap. This will result in a period of high revving that indeed does not correspond with your actual speed*. But after speeding away from a traffic light just once, this period should not last to long. How long was it with you, BTW? Also, it would not explain why you would have poor acceleration. Reduction of power should only happen when you reach an SOC as low as 17%, but before that, you would have met the turtle.

* As a matter of fact, the car could drop out of parallel drive to re-establish SOC, when this happens at higher speeds. IIRC this happens at 22% SOC and stops when 25% is achieved. Not something you would encounter quickly, other than when climbing or towing.

 

[maby]

The behaviour that I describe probably went on for about four or five minutes - the trip to the supermarket would be a couple of miles each way - but the SOC definitely was not getting down to turtle - I believe it was on one bar all the time. I'm not sure how much faith to put in the instrumentation - the car seems to just get into an abnormal state. I think it is the same condition that others have referred to when they talk about the engine screaming up a hill - I've referred to it myself when the car behaves dramatically differently climbing the same hill under apparently identical conditions on two different occasions. I think the trigger is a brief demand for high power on a flat battery but having got into this state, it can carry on for quite a few minutes - this could explain why some drivers, myself included, seem to see it often while others don't believe it exists - I do demand quite a lot of the car sometimes and simply trip it over quite often. if you drive it more gently and try to live within the EV range, you could easily not see it.

 

[greendwarf]

.....

BTW: Could it be that, before reaching the flat road, you had done some climbing and exhausted the battery further than the low water mark? And that the system was still recovering from that?

No climbing - we left the house in an ambient temperature of 16 degrees and the climate control set to 21. The route from our house to the station is completely flat (apart from a couple of speed humps) and probably just over a mile. The battery had not been charged for a couple of days and was showing one bar - the engine kicked in - which was to be expected - but revving quite high and unpleasantly high on moderate throttle opening. It is certainly not the way I like my car to behave - and very reminiscent of a Prius with a flat battery.

But surely this should be expected if you ask the car to drive and provide sub-tropical conditions from a cold start with no battery support and why wouldn't it be the same as a Prius under the similar conditions :?

 

[greendwarf]

OK - update based on experiences this afternoon...

I wonder if we have different perceptions of the car because its behaviour is not particularly deterministic and we simply do not see the same car a lot of the time. I just went shopping - with my still flat battery and it started out behaving itself very well - running in a mixed mode with periods of pure EV and periods on ICE but the revs kept down to the point where I had to look at the power flow to be sure if the engine was running or not. This carried on for a couple of miles to the shop, but traffic was fairly heavy and I could not go very fast or accelerate much.

I came out of the supermarket and started out for home - car still behaving the same - then the traffic cleared and I accelerated hard off the lights - and everything changed. The engine fired up and revved hard although acceleration was not very good - and that became the pattern for the rest of my trip home - engine running all the time, revving quite high even when stopped and when I accelerated, the revs went up high, but the acceleration was poor - I had the left hand gauge round to the three o/clock position with the engine running fast and the car doing 20mph. The battery gauge never dropped below one bar.

I've seen this before, but never analysed it so carefully. It was the same as I saw this morning when my wife was asking why the engine was racing. If you never accelerate hard from stationary or close to stationary with a flat battery, you may never see it but once you trip it over to that state, it seems to stay like it for a long time.

I'm not surprised that the car was better later in the day when not starting from stone cold but what you describe for the return is what I would expect, although I don't know why specifically. I've noticed that the best way to get the fastest acceleration is to be either already rolling e.g. for overtaking or by gently "squeezing the trigger" from stationary (e.g. at lights) - remember Scalextric? - rather than just stamping on the accelerator.

It may be that because the ICE is actually driving the electric motors we need to modify our driving style more than expected. Has anyone managed a drag race wheelie?

 

[Grigou]

The power meter (left dial) shows how much power is used for driving alone.

Thank you for this precious information.
Even if I use it often when driving in EV, I had never thought about the precise meaning of the power meter before.