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Discussion Starter #1 (Edited)

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Discussion Starter #4
Can't explain it Paul you will just have to take my word for it. Hold mode when going uphill and gather the regen when going downhill - plenty of hills in Scotland. The was on a trip from Portsonachan to Fort William and back.
 

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I've seen regen added back on like that when I was doing a lot of hills through the centre of Wales, even more if you use it in Mountain mode. Still doesn't take anything away from 6.24m/kWh! I bet most of it was about 30-50mph?
 

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I have never seen any regen added to the electricity used. In fact, I am pretty sure that the only way that can get above the normal 10.3 - 10.5 is by plugging in... so I am confused :confused:
I'm confused too Paul. It's got to be hold mode. Surely if we burn petrol in hold mode, the car is going to be using petrol to keep the battery charged at that level, including when the car uses a bit of battery to give a 'boost' in hills etc. I'm not sure we should be including use of hold mode in these clubs ;) Surely it has to be battery only, in continuous use, no petrol burning allowed from start to finish?
 

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I have never seen any regen added to the electricity used. In fact, I am pretty sure that the only way that can get above the normal 10.3 - 10.5 is by plugging in... so I am confused :confused:
Its to do with model year, the 2012 takes the regen off of your kWh used the 2013 adds it to the kWh used
 

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Can't comment on the use of Hold whilst battery power remains, because I haven't felt the need to do it. However I have noticed that once the battery is depleted and running on ICE, it adds kw/h to the battery, like it's generating more energy than it needs to help top up the battery a bit, so that when under load it has the power of battery and ICE. The max power available from the ice is not as great as the max power available from the battery.

So in summary, it's acting like a plug in and not a true reflection of how much mileage you get from one complete battery charge alone. I would argue therefore that a 70 mile club is impossible with the 10.6kwh charge. Discuss! ;)
 

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Agreed, as soon as you flip to petrol power, the first thing it does is add a buffer to the battery which skews the figures. I think really the "clubs" have to reflect using the electric power only, no Hold/Mountain mode and making a note of the miles travelled (with kWh) at the point when it changes over to petrol... otherwise your extra range is from the engine running in Hold or (especially) Mountain mode, adding to those kWh readings.

On the other hand, if it's adding in the kWh correctly, then the miles per kWh should still be right :)
 

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Discussion Starter #10
Agreed, as soon as you flip to petrol power, the first thing it does is add a buffer to the battery which skews the figures
From the Manual:
Code:
Hold mode is only available when the vehicle is in electric mode.
This mode places the remaining battery charge into a reserve for the
driver to use as desired. Selecting this mode transitions the vehicle to
extended range mode to maintain the battery charge reserve
Nothing there about charging the battery or about adding a buffer!

In fact quite often when in hold mode the displayed battery range drops a mile. This in my experience was ONLY put back when regeneration took place and the original hold level was only ever exceeded when in "normal" mode and generating regen on a long downhill stretch
 

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Hmm, must admit my experience has been rather different... watching what happens when I press Hold, it starts the engine shortly afterwards, then runs on both, and then using the new energy usage monitor on the dash, I can see it steadily pumping charge into the battery for about 3-4 minutes. After that point, it maintains this extra buffer, as when I change back to Normal mode, I magically seem to get extra mileage above what's shown. Using mountain mode makes this even clearer as it runs for longer to build up a bigger buffer, so that it can help the petrol engine when going up long hills without reducing the "Hold" mileage value or overstressing the engine.

I should add that the buffer isn't shown on the battery gauge, which is why it's not really apparent unless you look at the charging that's occurring...

Remember, the user manual doesn't always explain in detail what's really going on under the bonnet :)
 

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It's clearly visible on the power flow meter that the ICE adds power to the battery when the battery is depleted, but I haven't tried it in Hold mode. I can understand using Mountain mode if heading to the Highlands...but I didn't need to bother in the Lake District. What's the point of Hold mode in the UK where there aren't any zero emission zones?
 

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Discussion Starter #14
What's the point of Hold mode in the UK where there aren't any zero emission zones?
Battery to the nearest Motorway/Fast Road then petrol and battery for the last bit where you are probably on local roads again.

IMHO Petrol is more efficient at 70MPH on the motorway than using the battery power - but it does of course depend on how far you are travelling.
 

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Think I certainly need to do a bit more playing with settings in that case; I've only had it since June.

I have noticed that at the end of my journey when on depleted battery, the engine sometimes revs, even at low speed and I don't know why it's doing that.
 

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Discussion Starter #16
I have noticed that at the end of my journey when on depleted battery, the engine sometimes revs, even at low speed and I don't know why it's doing that.
I suspect (but others will confirm) that if the battery is depleted and the engine is revving then it is just replacing the low end charge to maintain the batteries charge state. It can dip into this when the battery is empty to cater for the odd higher load (hill or right foot) and then tops it up to the required level.

Only the centre part of the battery charge is ever used never going above 80% on charge or below 30% on use. (I hope I have the figures correct I am sure someone else will correct me if not)
 

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Hmm, I'm 99% sure there's a buffer above the hold value to be honest, and the engine is essentially replacing that. This also explains what appears to be erratic behaviour of the engine. Basically, in engine/Hold/Mountain mode, when you go up a hill after cruising at constant speed, rather than up the engine revs, it uses a bit of the buffer it's built up. If it's a long hill, after a bit, this buffer gets completely depleted so the only way to continue up the hill is to raise the revs so the engine power matches the electric power required. Say you then get to the top of the hill and go on the flat; even though the required electric power to the motors is less, the engine will still rev higher as it's building up the buffer again, and it will stay higher than the electric power required until the buffer has been built back up again, at which point the engine revs drop to match the actual power required by the motor.

Initially I thought the engine revs were a bit random but now I realise that it's doing the above, it's completely 100% predictable and consistent how the engine is used.
 

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Discussion Starter #18
@Richard Gledhill - But what happens (as in my case) when you get to the top of the hill you switch back into normal - the engine stops immediately it does not carry on running therefore no charge would be replaced.

In your scenario it remains running until the charge is replaced, when would you go back to normal mode?
 

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If you switch back to normal mode at any point, the engine does indeed stop and you can use whatever's left in the buffer, plus whatever the level was when you pressed Hold in the first place. In your scenario, at the top of the hill, pressing Normal would switch back to giving you exactly the same range as when you pressed Hold, since you've used up the buffer and were running on engine only at that point.

Generally it's less efficient to use Hold mode to try and effectively slightly recharge the battery (see other threads on using Mountain mode to recharge the battery, which is the same only more so), so it's not beneficial to stick Hold mode on for a while, as although you'll get better battery range, you will have spent more pennies on the petrol :)
 

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Slightly related: interesting post here too:

http://gm-volt.com/2012/09/18/optimizing-route-efficiency-using-hold-mode/

Basically he says that the most efficient thing to do is use electric mode only when going uphill, even if it means using Hold mode on normal level driving first! This is due to the ICE being inefficient at high RPM, which makes sense I guess.

This is why the engine normally hums away at about 2200rpm when it's doing its buffer charging, as this is the most economical/efficient RPM for the Atkinson Cycle that the engine is running.

I have the MyGreenVolt App on my phone, so sitting in the inevitable traffic tonight, I'll sacrifice some petrol to see if I can see the raw battery charge level go up, thus confirming the buffer explanation :)

(Hope everyone else is still awake!!)
 
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