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Discussion Starter #1
Hi, I'm new to this forum and have been driving my Ampera for about 3500 miles so far, frequently doing my regular run from Stroud in Gloucestershire to Newport in South Wales usually about 60 miles the long way avoiding the severn bridge toll.

I don't know if anyone has done this yet, but I have been harvesting regenerated energy on the route by driving in normal mode during a descent or decelerating into a roundabout and then quickly moving to hold mode on an ascent or roundabout exit to keep that energy generated. Then when I need it I will use the car in electric mode later in traffic. On the face of it this is not an efficient way to drive but I find I'm using less fuel (naturally) and then more miles on the battery power. On a 60 mile journey I can typically harvest 2.5kwhrs.

I will have to look at the physics of this a bit further, but since my workplace has not yet got its planned charging station this has helped in the final fuel used. To work this out properly I would need the genuine charge rates from the generator at different road speeds and then the Kw needed during acceleration. If there is a mis-match in these curves there is an advantage to be gained. I've also used the Lo gear setting to decelerate purely using regenerative retardation from high speeds and found it to be more effective than the brake pedal for generation.

I wondered what experience others had with doing this.

It is damned fiddly on the switches and the ampera is slow at switching modes, and the most dangerous thing of all is hitting the power button inadvertently instead of the drive mode button...you have been warned! If people agree with me that this works then a system of flappy paddles on the steering wheel would be the way forward, and it would add some interest in driving the car. Don't get me wrong I love driving my ampera, but when a silent car reaches 70mph it can get boring!

J
 

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Hi Julian and welcome.

It isn't necessary to do all that switching to achieve what you are after as the Ampera does all that itself anyway.

If you are driving on petrol then at any time the car is regenerating the battery is being charged. You can see that if you look at the power flow graphics. Even though you are not running in battery mode (i.e. you are using petrol) once the car switches to regeneration it charges the battery. It will then use that battery power when it next has the opportunity.

Obviously this is not saving up the power to use at a time of your choice but it uses it none the less there by reducing the petrol requirement.

I wouldn't have thought that you would gain much, if anything, from all that faffing around with switching and I would imaging that the Ampera is likely to do it all pretty effectively itself. But I could be wrong.

Besides, when I drive my Ampera, one of the pleasures is that it doesn't need that kind of micro-management for it to perform effectively so for me I wouldn't want to do all of that mucking around but if that is how you enjoy driving it then why not. :)
 

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Discussion Starter #3
Paul

Thanks for that. I understand that the ampera uses whatever it gains under normal mode, it runs down to the last 20% of battery and then uses that as a source and sink for when operating as a hybrid, but in the same way as a manual gearbox car is more efficient than an auto box (in general) then so can an ampera. A manual gearbox has the advantage that a human driver can anticipate road conditions while an auto box can only react to loads and demands placed on it in the split second. The same could apply to the ampera if you read the road on behalf of the car.

Until such time that the ampera's satnav includes elevation information its up to us drivers to anticipate gradients and traffic obstacles. Initially I thought I would gain little but in only three trips so far I have perfected gaining 2.5kwhrs.

While I know that GM sank zillions into the development of the ampera, tweaks like this have been left open ended. I understand that the next generation of GM models will be fully connected over 4G and with access to server based navigation and real time traffic info the potential is there for the car to make many efficiency decisions and we drivers are back to just turning the steering wheel and pushing the pedals! J
 

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Sorry to burst your bubble Julian but it cannot be extra energy. Regardless of which mode you are in you will use pretty much the same amount of energy to go from A to B and you will recover pretty much the same amount through regen. It is just physics.

I cannot imagine any scenario that might change that.

How do you know how much you have "harvested". I suspect this isn't extra energy you are getting but instead perhaps it is an accounting anomoly in how regen is recorded in the different modes.

Regarding your L vs the brake pedal... they are exactly the same. L simply remaps the pedals differently so that you get more or less regen when you are "feet off" and it maps the throttle more of less aggressively. If you are careful you will get the same amount of regen and the same range and accelleration in either mode but the balance of regen and the acceleration will change between the two modes requiring a different driving style.

Ideally, you will get more range out of any EV by not using regen at all and coasting to slow down whenever it is safe to do so. Coasting requires you finding the spot where you are not regenning and not using power. Don't go into neutral as that is probably not good for the car and not good driving practice.
 

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On a 60 mile journey I can typically harvest 2.5kwhrs. J
Hi Julian, welcome.
I too use this technique on occasions, but I am not sure anything is gained other than an increase in battery useable Kwh. The figures on the centre display show an increase in battery miles from the gain in Kwh but I am of the opinion that this is at the expense of petrol mpg due to the greater power requirement from the ICE during the ascent.
 

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Discussion Starter #6
There is one other aspect to this, and that is starting and stopping the engine. Petrol engines are much more inefficient in idle when compared to say, diesels. The ampera engine seems to have three standard power outputs, for the sake of description lets call them low medium and high, and in some instances I have noticed it idles. When only low power levels are needed it stays at low speed and dumps excess power into the battery (not efficient but it has no alternative, the electrical load has to go somewhere), and it does this frequently as the car decelerates, just before switching off (in hold mode) it then idles for a few seconds. Killing the engine by going from hold to normal mode at the start of deceleration or descent stops it from faffing around like this. Petrol engines are at their most efficient in the mid to high range and the 1.4GM unit from the astra especially so, you only have to compare the cruising revs of a corsa or astra to see this, put the same car in traffic and it turns into a guzzler. So, by keeping the engine fizzing at high revs during acceleration could ultimately be more efficient, we'd need some graphs from GM to verify this.

J
 

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Discussion Starter #7
Sorry to burst your bubble Julian but it cannot be extra energy. Regardless of which mode you are in you will use pretty much the same amount of energy to go from A to B and you will recover pretty much the same amount through regen. It is just physics.

I cannot imagine any scenario that might change that.

How do you know how much you have "harvested". I suspect this isn't extra energy you are getting but instead perhaps it is an accounting anomoly in how regen is recorded in the different modes.

Regarding your L vs the brake pedal... they are exactly the same. L simply remaps the pedals differently so that you get more or less regen when you are "feet off" and it maps the throttle more of less aggressively. If you are careful you will get the same amount of regen and the same range and accelleration in either mode but the balance of regen and the acceleration will change between the two modes requiring a different driving style.

Ideally, you will get more range out of any EV by not using regen at all and coasting to slow down whenever it is safe to do so. Coasting requires you finding the spot where you are not regenning and not using power. Don't go into neutral as that is probably not good for the car and not good driving practice.

I can see the amount I've harvested by seeing how much over the standard 10.6KWhrs I've used on a trip. J
 

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My findings on this are that it will not help your overall MPG for a specific journey much but will show you have driven further on electricity. I feel its alot of messing about for not much gain!
Having said that I did gain half a charge decending from 8451ft (2576m) on the GrossGlockner mountain pass in Austria!

My Dad (LK13) might have a different view. I know he is forever switching his Ampera between Hold and Normal to gain extra KWH'S down hill.
 

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Yes, I too feel that it is probably an accounting issue... showing more kWh used than had you not done it but I suspect that the reality is that you would have had the same power use as if you hadn't done it but the figures wouldn't show.

Mind you, I am certainly not saying you are definitely wrong! I have no proof either way and I am just commenting based on my understanding of how the Ampera works and basic principles of EVs... I would love to know the facts :)
 

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Yes harvested power is not accounted for in the electrics figures when in Hold Mode, so switching only changes the accounting not the physics. You'll notice the deceleration is the same for both drive modes ergo the same power is being harvested in each mode.
I'd suggest using total mpg as best figure for comparrisions rather than electrics kwh used.
I wouldn't bother with the faffing as the car will likely do equally well (in final mpg) by itself.
 

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Discussion Starter #11
As I understand it the Ampera has one drive motor, and a smaller motor/generator, so you're proposition is correct as the car will only be decelerated by the same motor/generator irrespective of the drive mode. I will have to do more trials on the same route which is:

Stroud to Gloucester, short stretch of motorway
Through Gloucester, town stop start
Gloucester to Newent trundling along country road below 50mph
Newent to M4 J24 dual carriageway across Hills interrupted by roundabouts and junctions at Ross on Wye and Monmouth
M4 J24 to J28 slow motorway with stop start around J28

I use normal mode up to Gloucester to run some power out of the battery to allow it to work as a hybrid as I noticed that if you go into hold mode with a full battery the mpg is about 25mpg! I can only assume that with a full battery the system can't dump excess to the battery and balance its load. Just before Gloucester I use hold mode, then up to Newent I use normal. Then all down the A40 and A449 I will harvest as much as I can at every downhill and roundabout, yielding an extra 2.5Kwhrs as I said before. The slow motorway stretch can be done efficiently in either mode, but I save the battery then for the inevitable return crawl back up the M4 (I use the M4 and M5 for the homeward journey as there is no toll going back to England).

On each run so far I have had a higher mpg and the extra battery miles, I put it down to planning for the traffic conditions ( I regularly lookup the hold ups and ring traffic master) and keeping the engine working hard rather than at low revs. If the Ampera was a diesel electric I suspect this method would not work as well. I've done a lot of engine dyno work in the past but I'm going to discuss this with someone with experience of modern engines. I've even been offered a road dyno to do some tests.

I would be interested if anyone out there has experience of the new Volvo V60 plug in hybrid, which has a diesel unit.

J
 

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I am with Paul on this and suspect it is just numbers but it would be fascinating to be proved wrong!

The one bit of ”fiddling” I do is if I am doing a journey I know will need the engine before I get to my destination and it is a day I need heat...I then start the journey in Hold so that can heat the cabin using free engine heat, and then switch to Normal once I am toasty. The same applies to restarting after stops/breaks. The rest of the time I drive in L.

Just wondering if you have the heater on during your experiments as that could affect numbers/mpg/mpkwh?
 

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Discussion Starter #14
I try to keep the cabin condition as consistent as possible but I cannot regulate the weather and we all know what that does to battery performance! I also ban my daughter from using the seat heater until the engine is on!

I do think the engine control software is fairly crude, and never as subtle as a human right foot, and if the battery was not available for dumping excess power the Ampera would be pretty agricultural. I feel the development has gone into the motor and generator and traction control and the engine has been an after thought. I'm not sure of the history of the development of the Ampera, but did it start out as a pure electric vehicle?

J
 

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I do think the engine control software is fairly crude, and never as subtle as a human right foot,
Forgive me but it doesn't need to be :)

The ICE does not provide power to the wheels (except at very high speed/power) so it is not needed to do anything other than run at a fixed speed to drive a generator. OK, you have mentioned that the speed it runs at is controlled in a pretty crude way but that is the nature of the beast. It doesn't really need to do anything else as the ICE only generates electricity. That electricity is either used at time of generation or, if there is a surplus, it is stored in the battery.

The only way it could be more efficient is if it always ran at optimum speed and as you have said that is a high speed so we wouldn't want it to do that.

I think you are looking upon the Ampera as if it is a normal petrol car... it isn't and I wonder if whether that is the source of your comments?
 

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Discussion Starter #16
Not at all, I've taken the time to study the Ampera since its launch, what provoked me to get one was a change in Fuel policy by my employer that now rewards frugality over profligacy (my last company car was a Discovery). I work as a Senior Expert in the Aerospace Industry with a specialism in Energy and propulsion, and the upcoming hybrid jet engines with high bypass fans powered by electricity will soon overshadow what is happening in automotive engineering and is very exciting. What is essential in managing such hybrid systems is good systems engineering across the hybrid interface. Within Aerospace we have to get things right first time as no-one likes an air crash. Cars on the other hand if they don't work they stop at the side of the road and people get out and look to see what the matter is, and also if they are inefficient, thats OK because you can go and buy a rival car or wait for the next version.

All I'm saying is that observing the behaviour of the two systems on the it seems that the electrics came first and the engine second, that's OK its not a criticism of GM, its just that I can see that there is a way of making things better, and though the margin might be small the automotive engineers will go for every tenth of a percent improvement they can, because they know that when you choose your car you will rank it against its rivals.

I think as the first generation of mass EV drivers we have a sort-of duty to say how things could be done better...look how we were caught napping over Chargemaster's policy! We should be feeding back to GM and Nissan etc at every opportunity, and no doubt the rest of you guys do when you're given the chance.

J
 

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I have no idea which came first or second... I am just comment on the fact that there is not likely to be a genuine saving of an extra 2.5kWh just through switching modes.
 

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Can I put my twopennyworth in?

From way back in my Motor Vehicle Engineering days I seem to recall that an ICE runs most efficiently when producing its maximum torque. (Something to do with ideal air fuel ratio I think)

Most current ICE power units are designed with a very broad spread of torque to achieve the best fuel efficiency. I'd think that the ECU in the Ampera has been calibrated to ensure that at each of the three (?) engine speeds it is working at optimum efficiency. It does not afterall need to be overfuelled to provide "smooth acceleration" as it would if mated to a regular gearbox. I'm certain GM didn't just take the 1.4 engine and ECU (used in the Astra) without optimising its control units for the Ampera's alternative use.

By the way I'm in the camp that suggests leaving the software to do it's own thing is not going to be beaten by manual intervention. The variations in energy used over the same route could, in my experience, easily be accounted for by weather and traffic conditions!

Big Paul
 

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Discussion Starter #19
Hi, I certainly appreciate the weather angle. I'm going to conduct more research and rope in some experts to check this out. I'm not saying the GM engineers didn't do their stuff, but I do know the evolution of the volt/ampera was not without its problems, I remember that the GM hybrid van based on the ampera principles was ditched in order to support the ampera in the market and conserve r&d funds...in many ways I would have preferred the van a few years back in people carrier form. I also know that accountants and project managers frequently tell the engineers: 'enough is enough, lets get this thing to market', I can mentioned a dozen products that were not complete when marketed, and the latest ampera recall is just such an example. Now engine/motor balancing would have to be the subject of continual testing to get right, and that is v expensive. The volt/ampera was developed when the car industry was in deep recession so I'm prepared for that fact that it will be imperfect, but in a way that encourages me to find constant ways to improve it, I suppose I've spent too many years getting two sons through karting not to understand the significance of minute improvements culminating in a winning margin.

I will report back in the next few weeks if I have evidence one way or the other.

J
 
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