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Discussion Starter #1
Does the Ampera have a 12v starter battery (for the petrol engine) as well as the main batteries, or does it use the main batteries for starting as well?

I'm guessing separate as starting batteries usually need more cranking amps than a leisure type battery.

If so which battery powers what? Are the lights etc powered by the main battery or starter?
 

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Thats right - "standard" 12V battery does everything you're used to as normal and the "high voltage" battery does the propulsion. Its also has some clever 12v battery discharge protection - if you leave the interior lights on etc with the ignition off it will turn the them off after a while.
As for starting, the ICE normally starts only when you're already moving so does it use the battery? I dunno - anyone?
 

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I imagine the petrol engine is spun up to speed through the planetary gear set (i.e. uses power from the main/traction battery) and then fuel is injected. That's how the prius does it. It lets you do a soft start on the engine, get all the oil pumping etc so it's very gentle, and means you don't need a separate 12V starter motor.
 

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Discussion Starter #5
On that basis, if you were to charge your 12v battery as well at home to maximum capacity you should get even more from main battery as the car will have no 12v battery to charge!
 

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I imagine the petrol engine is spun up to speed through the planetary gear set (i.e. uses power from the main/traction battery) and then fuel is injected. That's how the prius does it. It lets you do a soft start on the engine, get all the oil pumping etc so it's very gentle, and means you don't need a separate 12V starter motor.
It would seem so - there is no obvious chukker-chukker-turn-it-over sensation. Of course the ICE can sometimes (rarely) start when stationary (if you've activated pre heating when very cold if not pluggged in for example) so then I guess it uses battery / starter motor?
 

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Yes, the Standard 12V battery is in the boot next to the 13A charger (there are little hatches if you need to access it) It's a fairly large battery because it has to power heated windows and seats(maybe even the cabin heaters?), but not the starter motor. The engine is started by the 'generator motor' (this is not normally connected to the drive train so can start at will even when stationary) not the main 'drive motor', once the engine is running the 'generator motor' goes straight to generate mode.
 

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I'm sure
On that basis, if you were to charge your 12v battery as well at home to maximum capacity you should get even more from main battery as the car will have no 12v battery to charge!
I'm sure I read somewhere that you should not attempt to charge the 12v battery yourself, as the car expects to do this in it's own way and you can confuse it...maybe even damage something. Basically, you can forget about the 12v one as far as range or efficiency goes.
 
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On that basis, if you were to charge your 12v battery as well at home to maximum capacity you should get even more from main battery as the car will have no 12v battery to charge!
Maybe, although the gains would be measured in the feet instead of the mile. Don't bother!

It would seem so - there is no obvious chukker-chukker-turn-it-over sensation. Of course the ICE can sometimes (rarely) start when stationary (if you've activated pre heating when very cold if not pluggged in for example) so then I guess it uses battery / starter motor?
No, the ring gear is locked to the case and the smaller motor generator acts as a motor to spin up the engine (the torque can't be transferred to the drive wheels because the ring gear is locked, so it has to turn the engine). Once the engine is producing power the MG turns back into a generator.

This switching of the ring gear from locked to the case to locked to the second MG is how you get parallel drive mode, which always switches in at 58mph and always transfers 69% of the engine torque to the wheels.
 

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This switching of the ring gear from locked to the case to locked to the second MG is how you get parallel drive mode, which always switches in at 58mph and always transfers 69% of the engine torque to the wheels.
What is your reference for this Edd?

Your statement implies that above 58mph it always runs in parallel drive mode and I believed this not to be the case. Parallel drive mode rarely engages on the Ampera and only at higher speeds and power demands. Are you not mixing this up with the Prius?

The way I understood it... It isn't a ring gear that switches in parallel drive mode but a extra clutch... the Ampera has 3 clutches to control the power to the planetary gear... or are you saying that it is the clutch that does that locking/unlocking?
 

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I've seen various speeds quoted, but it seems parallel mode can be used at quite low speeds, 34mph I think is the figure I've seen but I don't have the reference to hand.

There are three clutches as you say, one locks the ring gear to the chassis, one connects ring gear to the motor generator, and another connects the motor generator to the ice. To start the ice the ring gear is always locked to the chassis and disconnected from the second motor which is used to spin up the ice. Once it is running it either continues as a generator it disconnected from the running ice, stops, clutch connects to ring gear, other clutch then disconnects ring gear from chassis, then the motor matches speed to the ice while the main motor slows down. Once the motor generator has matched speed with the ice the clutch can engage again allowing the ice to provide drive direct to the ring gear through the generator.
 

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What is your reference for this Edd?

Your statement implies that above 58mph it always runs in parallel drive mode and I believed this not to be the case. Parallel drive mode rarely engages on the Ampera and only at higher speeds and power demands. Are you not mixing this up with the Prius?

The way I understood it... It isn't a ring gear that switches in parallel drive mode but a extra clutch... the Ampera has 3 clutches to control the power to the planetary gear... or are you saying that it is the clutch that does that locking/unlocking?
I'd suggest here:

http://gm-volt.com/2011/12/09/solving-the-volt’s-extended-range-combined-mode-power-split/

and here:

http://gm-volt.com/forum/showthread...-unit-has-four-basic-modes-of-operation/page5

but @Duncan has it right.

Definitely not confused with the Prius, it's magic speed is 46mph, and with no clutches at all. :)
 

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This switching of the ring gear from locked to the case to locked to the second MG is how you get parallel drive mode, which always switches in at 58mph and always transfers 69% of the engine torque to the wheels.
hmm I'm not sure about that. As long as I have battery range left it seems to whiz along at 90mph without the ICE being engaged at all. When I say "seems" the power flow display shows "battery power" as opposed to "engine and battery" or "engine" and I can't detect the ICE at all.
 

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hmm I'm not sure about that. As long as I have battery range left it seems to whiz along at 90mph without the ICE being engaged at all. When I say "seems" the power flow display shows "battery power" as opposed to "engine and battery" or "engine" and I can't detect the ICE at all.
My apologies, the sentence above should start "When in Charge Sustaining mode"
 

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aah yes I was about to suggest that. Is this the difference compared to the Prius? When you have battery capacity it runs always as a pure EV at any speed and only when in CS (or Extended Range) mode it behaves as described above. Even when battery range is "exhausted" it still runs on battery power only at low speed and then does this combo dance as demand rises.
 

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aah yes I was about to suggest that. Is this the difference compared to the Prius? When you have battery capacity it runs always as a pure EV at any speed and only when in CS (or Extended Range) mode it behaves as described above. Even when battery range is "exhausted" it still runs on battery power only at low speed and then does this combo dance as demand rises.
That's right, there was some speculation that perhaps the ICE would need to spin when at high speed in Charge Deplete mode, to keep the main motorgenerator in a tighter RPM band, but this can be accomplished by opening the clutch between the ICE and the smaller motorgenerator but closing the clutch between that motorgenerator and the ring gear. The smaller generator then acts as an electronically controlled CVT.

No denying, it's all very smart!

If I had the skills I'd take the source code from this model:

http://eahart.com/prius/psd/

and make one for the Volt, it'd be fun to play with :)
 

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This switching of the ring gear from locked to the case to locked to the second MG is how you get parallel drive mode, which always switches in at 58mph and always transfers 69% of the engine torque to the wheels.
So there is a mechanical connection between the ICE and the wheels? Interesting, from what I read when it came out (and the wikipedia page a while back) I didn't think there was, it looked like the generator just supplied extra electricity to motor...
 

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Discussion Starter #20
In the manual it says "if you charge the12 volt battery, use the agm setting on your charger, if you have one".
 
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