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In my pondering over switching my gen 2 Leaf for a Volt I've been deliberating over the pros and cons of each vehicle.

The Amperas resistive heater is one of the cons compared to the heat pump on the Leaf, given on cold days the Leaf estimates I loose 9 miles to heating its hard to imagine worse efficiency!

But what I don't understand, and this might be one for @donald (from my reading on here) is assuming the heat pump uses the air con compressor in a reverse fashion of sorts (I appreciate its more technical than simply reverse) firstly why don't all EV's use this seeing as they all have A/C anyway.
Secondly I have been led to believe that with mains powered heaters there is no significant difference in efficiency between an electric oil radiator or a fan heater of the same power - all that changes is the speed with which energy is transffered to the room via preheating oil in a radiator vs instant transfer in a fan heater. What I'm getting at is why should the energy losses in a resistive heater be greater than those in a heat pump? Which translates into less miles and so supposedly makes an Ampera marginally more expensive to run in the winter even if preheating via the mains.

Maybe I could have written the above in a single sentence but for anyone interested in the topic you'll have to forgive me!
 

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I see you are a recent member - Welcome.

@donald drives a diesel now so has no problems keeping warm nor any issues with range ;)

He does have good technical knowledge though and I am sure will chime in shortly :)

You don't say why you are pondering changing and that (to me) is important. Do you currently have a backup ICE for long journeys or do you cope with many charging stops which a 24kWh entails.

Do you commute within or beyond the range of the Ampera as if most journeys are well within the range, why does efficiency matter?
 

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A heat pump transfers energy from one area to another using energy (Simplistic)
An AC unit is a heat pump as It shifts heat from inside the car to outside the car using some energy, in the process heating the external world.
Reverse it and heat is moved from outside the car into the car. In simple terms you use a little energy to move a larger amount of energy from one place to another (heat in this case).

I used to have a diesel with a reversible AC so on a cold morning you could get instant heat. That was long before EV's

The Amp is interesting as it can generate heat and electricity by running the engine so you can get heat and extra electrons by running the engine. This is what I do when its cold. Run the engine to warm the water, turn off the engine and use the residual heat to keep the car warm. A little petrol goes a long way as heat ;)
 

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The simple reason why the Amp doesn't have a reverse heat pump is simply because it adds complexity to the car and as @Spiny says, it has the capability to use the waste heat from the ICE as well as by using a resistive heater.
Another point is that it is very quiet compared to the rattle that my partners Zoe made when in operation.
Reverse heat pumps are pretty poor when it is very cold, just when you need it.
 

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Secondly I have been led to believe that with mains powered heaters there is no significant difference in efficiency between an electric oil radiator or a fan heater of the same power - all that changes is the speed with which energy is transferred to the room via preheating oil in a radiator vs instant transfer in a fan heater. What I'm getting at is why should the energy losses in a resistive heater be greater than those in a heat pump?
Electric radiant heaters are 100% efficient in their use of energy as it is virtually all turned to heat, none to light. Its just that it isn't so efficient to burn coal or oil, turn that heat energy to electricity, pass that electricity down distant cables and transformers before it reaches the heater. That is very energy inefficient.
 

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Discussion Starter #6 (Edited)
Do you commute within or beyond the range of the Ampera as if most journeys are well within the range, why does efficiency matter?
Thanks for welcome, i've found everyone to be so helpful and friendly - this site is such a fantastic resource.
Most days in would be well within range, but I was somehow imagining the heater to use so much range as to make the Ampera significantly more costly in electric to run, but I realise this is probably nonsense, if its an extra kw that's 13p!

A heat pump transfers energy from one area to another using energy (Simplistic)
An AC unit is a heat pump as It shifts heat from inside the car to outside the car using some energy, in the process heating the external world.
Reverse it and heat is moved from outside the car into the car. In simple terms you use a little energy to move a larger amount of energy from one place to another (heat in this case).
Thanks clearly there are a number of people on here with technical knowledge then! You've explained it superbly, makes a lot of sense then why a HP is efficient. Just dont get why they don't use it in reverse (heat mode) then on all EV's Ampera included? I get that engine is anyway providing heat, but Ampera is supposed to be 'self sufficient' in EV mode too - so why not use AC pump for EV mode and save some electrons?

Further edit! Sorry viewing on my phone at moment and didnt notice my questions already been answered above! Apologies and thanks for all explanations
 

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Reverse heat pumps are pretty poor when it is very cold, just when you need it.
Yeah, a common myth is it is one or other. You can't really have just a heat pump.
 

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Have you driven an Ampera yet? IMO it drives a lot better than the Leaf 24/30 and is almost sporty in handling. It sounds like the New Leaf may have caught up - but I will wait to see for myself ;)
 

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Even the Gen 2 LEAF starts heating with a resistive heater on cold days. It switches to the heat pump when the heat pump can cope so to speak.
 

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But what I don't understand, and this might be one for @donald (from my reading on here) is assuming the heat pump uses the air con compressor in a reverse fashion of sorts (I appreciate its more technical than simply reverse) firstly why don't all EV's use this seeing as they all have A/C anyway.
I've written a few times on this, and maybe a search will find them (but it is not a very good search tool, I can't find stuff either!!).

The reason is simply cost. It would be cheaper just to throw in a few extra battery cells to cover the extra energy. Reliability is a second factor.

In the case of the Ampera the reason is partly because of engineering reasons but even if there were cheap, reliable systems, the Ampera is designed to make use of engine heat. So if you aren't going to make your trip on all-electric in the winter, then just run the engine and get heat off it that way, just don't bother using electric heating at all. If you do have enough electric, then just use that.

So for Ampera the reasons are 'platform-design' ones which is subtly different than the cost/engineering issue for BEVs.
 

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Discussion Starter #11
Have you driven an Ampera yet? IMO it drives a lot better than the Leaf 24/30 and is almost sporty in handling. It sounds like the New Leaf may have caught up - but I will wait to see for myself ;)
Funny you should say that, I actually posted about my finding it slow compared to my Leaf on the test drive -I revived an old thread called 'sport mode' to ask about the lack of zip as I did switch it to sport mode. I'll probably have another test drive on Sunday as I forgot to take it over any speed bumps and having done 130K miles its suspension might be a bit worse for wear. Will have another go at experiancing this extra power over the Leaf that everyone seems to claim (well everyone cant be wrong).
 

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Owning both, you definitely notice a difference but not as big as the figures might suggest. The LEAF pedal mapping makes it feel very zippy, especially when ECO is off. The Ampera requires a lot more pedal pushing before you get full throttle and so doesn't feel as responsive, even in Sport mode. The Ampera is quicker but in the real world they both feel zippy in urban driving conditions. The Ampera is a better performer at high motorway speeds though. One thing, the Ampera has 1980's Turbo lag performance when running in engine mode which mutes it's ability quite a bit. The new LEAF will be awesome with 150bhp.
 

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the Ampera has 1980's Turbo lag performance when running in engine mode
I am a passionate advocate of the Ampera and find it difficult to understand how you've not been wowed by its performance but if I had to list of things that I would change about the Ampera's design it would include:

1) that the acceleration performance level experienced when the ICE is generating the electric power feels so much less than in full battery mode. There may be a good technical explanation of why it doesn't and that is beyond me; I'm just commenting as a driver who would have liked it be designed to have a more consistent feel.

2) that there is such a difference in the performance of the heating systems between the two modes. Again I'd like the design to have given us consistency. Sometimes, I fail to notice that the battery range has expired and the first indication I pick up on is the extra heat in the cabin.

3) when you're in battery mode and then switch to Sport (for overtaking for example) you need to plan in advance when to make the switch because it takes a few seconds after pressing the button to have 'sport' power available. This is the longest "turbo-lag" I've ever experienced. I would also like the switch to Sport to have been a one-press operation, not a two-press.

4) having the ability to set 'optimum pre-conditioning' as an automatic option in the Config instead of having to remember to do it on cold morning and then interrupt breakfast to do it again.

But it's a great car and in a different class to a Leaf 2 IMHO
 

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1) that the acceleration performance level experienced when the ICE is generating the electric power feels so much less than in full battery mode. There may be a good technical explanation of why it doesn't and that is beyond me; I'm just commenting as a driver who have liked it be designed to have a more consistent feel.
Simply that the generator that is generating power when the engine is running can be used as a motor to provide extra power when the vehicle operating as a BEV. So performance is much more sparking in BEV mode.
 

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3) when you're in battery mode and then switch to Sport (for overtaking for example) you need to plan in advance when to make the switch because it takes a few seconds after pressing the button to have 'sport' power available. This is the longest "turbo-lag" I've ever experienced. I would also like the switch to Sport to have been a one-press operation, not a two-press.
Well it's a 'mode' not a boost button. Sport mode just remaps the accelerator pedal to provide a more sporty response, no extra oomph is generated. You can achieve best acceleration in Normal mode for overtaking etc.by flooring the pedal.
 

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I can understand you may not feel the linear performance of an Ampera with the standard pedal setting.

It is also conceivable that the noisier Leaf gives the impression of doing 'more', like an ICE experience. Far too many buzzy and whirry noises for my liking in a Leaf!

To remap the Ampera pedal to the tightest response, select SPORT mode and also select 'L' on the drive stick. Trust me, you will then have the experience you're after. All the response is then squashed into the middle third of the pedal displacement, instead of a half of the response over the whole pedal movement.

In regards the lag when accelerating on engine, there is indeed such a lag if you are coming from the cruise CS2 mode (it is a hybrid parallel mode). In CS1 mode (which is a serial mode) there is no delay at all. The reason it goes from CS2 to CS1 mode, which takes a second as the brake bands actuate, is because above 55kW demand has to be delivered by motor MGB, which can deliver up to 111kW. The smaller MGA is locked to the engine when it is operating and, as it happens (I am not sure it is entirely necessary) they isolate MGA and the motor during MGB hard acceleration.

I think the fear is that MGB might drive the engine backwards if a fault occurs on MGA, however for the Cadillac ELR they do exactly that and engage both motors and engine to deliver higher performance.

It is what it does. The lag is, basically, a gear change.
 

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To remap the Ampera pedal to the tightest response, select SPORT mode and also select 'L' on the drive stick. Trust me, you will then have the experience you're after. All the response is then squashed into the middle third of the pedal displacement, instead of a half of the response over the whole pedal movement.
Very interesting you say that selecting L also helps give a more responsive performance when Sport mode selected. I thought it seemed to be so but never seen it referred to before. Its the way I always drive around town.
 

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One thing, the Ampera has 1980's Turbo lag performance when running in engine mode which mutes it's ability quite a bit.
I thought I was the only one who had this. It is very noticeable and almost certainly due to the description @donald gives above.

What I do get and others have not mentioned is an occasional bad jerk from the drive as I reduce speed to leave a motorway or just slow down.
I never get it on normal road driving but it is quite a jolt, most likely from the clutch bands swapping over.
Does anyone else have this problem?
 

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There should be no jerk. There can be a surge as the motors swap over the duty of power, this occurs around the 30 to 40 mph range (CD2 to CD1) but it should not be a jerk, unless you are very sensitive or something is amiss. The software should accommodate shift changes and speeds as the transmission ages.

If you can see ahead and have a planned acceleration, eg overtaking, and want to avoid the 'lag' in acceleration, then do a 'pre-acceleration' and this initiates the change from CS2 to CS1 (it is the same in EV only too, CD2 to CD1). Just dip the pedal (make sure you are not too close to something!!) and then you'll be ready to go instantly.

It would have been helpful to have some manual intervention over this, for example they could have programmed it to boot down into CD1 and stay there fore a minute when shifting from D to L, this would give the manual intervention to avoid the delay, but it is just what it does. The closer you get to perfection, the easier it is to pick out the flaws!!
 

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The jerk when slowing from motorway speed can be quite considerable. It is not every time though and the first times it happened a couple of years ago I really thought it was bad and that the drive was self destructing.

My thoughts on it was that I always drive in "L" mode for one pedal driving and maybe the high regen from speed was causing the issue and the software was getting confused when swapping brake bands.

Will advise at my next service.
 
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