[Electrons]

I don't know if this is technically possible, but let's say that I don't care about mileage and just want MAXIMUM juice to the motor for some really nasty torque. Sport mode is really good, and I can say usually leaves every one else behind at the red light.

But could we get more?

 

[mixedpixel]

Even in sport mode, torque is limited below 10 mph to prevent spinning out. Theoretically you could use more of that torque off the line.

 

[wainair]

I had read somewhere that Mr Lutz wanted the Volt to be a 6sec 0-60car and apparently the car is capable of it, but then the more conservative types had the acceleration toned down to limit the draw on the battery. With battery tech being so new in the car it was probably a good idea that they did that until they had a better idea of how the drive batteries were holding up in the real world. That said the capability is still there to get a 6second 0-60, it is just limited by the throttle controllers as I understand it. If you had a tuner that could access the throttle controllers you should be able to reprogram them to let you run faster/accelerate quicker, just don't expect your drive battery to last as long.

 

[petefoss]

It would really be fun to see what acceleration and top speed you could get with 110KW drive motor + 80 HP engine pushing at the same time. I don't think we could route battery power to the generator too with the engine running. Or could we? As a tranmission engineer, I'm a heck of a plastics engineer <grin>. Expecially planetaries. They are magic as far as I am concerned.

 

[saghost]

It would really be fun to see what acceleration and top speed you could get with 110KW drive motor + 80 HP engine pushing at the same time. I don't think we could route battery power to the generator too with the engine running. Or could we? As a tranmission engineer, I'm a heck of a plastics engineer <grin>. Expecially planetaries. They are magic as far as I am concerned.

As I understand it, the structure of this planetary won't allow it - because of the gear ratios involved, the engine and second drive motor have to produce nearly 2.5x as much torque as the main drive motor - and their combined output is somewhere close to the main motor's output.

This was good for range/efficiency in extended range mode, because it sends most of the power over the mechanical path instead of the electrical one, but it means that if the engine is clutched in, you can't use most of the main motor's drive torque. At higher vehicle speeds (>70?) you might get more total power to the road doing that (because the main motor can't deliver its full torque once it becomes power limited at ~30 mph,) but at low speeds it'd slow the car down.

This is where the super-HSD plug in hybrids (Ford C-Max, Fusion - possibly some others from the limited descriptions so far,) have an advantage - because their main drive motor is on the wheel side of the planetary, it can deliver full power regardless of the operations of the engine, and thus can add engine power directly to battery power at low speeds, to the limits of the power electronics. They pay for it at higher speeds with back EMF on MG1 that they can't eliminate and a higher percentage of power having to pass electrically. They also can't start the engine without pushing something through the planetary set - which is why they don't do it in neutral at all, and why they surge when it happens (though they often try to mask the surge with a matching power pulse/drop in MG1.)

Decisions, decisions. GM made a wise choice for a mostly EV - just not one that most people understand the downsides of (149 HP electric motor, 86 HP engine - so it must have 235 HP to accelerate, right?) Then again, most people don't understand how little power is getting to the ground most of the time anyway. The Volt is faster than most "200 HP" cars of it's weight because it puts power to the ground at lower RPMs.

 

[DCFusor]

The histogram once posted here showed a current limit if carefully examined, for low speeds, turning into a power limit at higher speeds (current going down with speed above 46 kph ~ 29 mph, as motor voltage goes up to compensate the back EMF it generates). Whether this is due to battery protection, motor magnet protection, or limitations of the inverter is not published, but there it is. You can do immediate and permanent damage to a PM motor with too much current - depolarizes the magnets and that's that.

Note this is shown in terms of power vs speed, so you mentally have to back out the P = I * E equation. Once you do that you see a current limit fixed at one amperage for acceleration, and a lower one for deceleration (regen).

This makes it look to me a little like the limit is what the motor or inverter can take. It's normal for a motor-generator to be able to utilize more input (before losses) than it can reasonably make in output (after its losses), other things the same. As you can see, nothing whatever magic happens at 10 mph (16kph). It's just a current limit, or appears like that. The constant power vs speed above that is ???. Is it that the back emf of the motor limits how much we can get it to draw at 360v, or GM deliberately limiting peak power so we don't drive like idiots and really reduce range trying to pass everyone on the highway? Or just protect the battery.

From the battery side, power is going to translate pretty directly to current, since the voltage is more or less fixed.
So we limit current to the motor at low speeds - less than max power, but at higher speeds, we limit current from the battery. Whether that could be changed (higher motor current at higher speeds - since we already have it at lower speeds) is the question, I suppose.

Sure, I'd love to have more now and then, but honestly, ricky ricer drifter/racer has tried to race my Volt on the twisties and I really didn't need any more to wipe the road with him - 8 times in 9 miles. I'd just stop till he came into the rearview and take off again, him revving and squealing and drifting behind me. Funny! Of course, it didn't hurt I was driving that road before he was eating food that required chewing and have named every bump and ripple so I can get max speed through the corners by missing same...old age and treachery vs youth and enthusiasm.

 

[250volts]

DC Fusor I so do enjoy your posts both from the technical level (impressive) and from the funny side. Wiping the ricky, ricer drifter/racer was hilarious! Find the same thing with my car. Hill climbs are a hoot and throw in some twisties and it puts a grin on my face that most Porsche enthusiasts would appreciate

 

[Electrons]

DC Fusor and al., you guys are awesome to read.

It is true what they say about the Volt; only intellects buy the car... and accountants lease it (I made that one up - since I'm an engineer and leased. oh well.)

More perky starts are on my wish list for sure. This is a man thing, irrational but while I am not interested in going above the speed limit... I'm just trying to get there faster. I love the Volt's acceleration, so for me and my kids this car IS a success already.

 

[HiVOLTage]

http://www.intapeople.com/engineeri...gy-could-improve-electric-vehicle-efficiency/

GE improves motors design to give 2x's the acceleration on lower battery voltage(longer range?) coupled with Envias new battery technology ...the future looks good!
http://www.energyandcapital.com/articles/this-battery-could-triple-the-chevy-volts-range/2447

 

[Electrons]

This is great news HiVOLTage! Thanks for the links I am very excited. Maybe this technology will be there when my Volt lease it up, in 2 years...

 

[Electrons]

Is it possible to implement the "ELR" mode on the Volt?