When does ICE drive the wheels

[WopOnTour]

I might resemble that nickname but I totally get why you don't like it. I could pass on it too! LOL

Haha I can almost guarantee I'm probably older and more "saggy" than either of you!
LOL
I'll drop it Walter, all in good fun
WOT

[George S. Bower]

Well I can say that saggy pretty much as it nailed to the proverbial "T".

ICE is NEVER to sole provider of propulsion, however there are instances (once in CS mode ONLY) where it works "in conjunction" with torque from the traction motor (MG2) to do so, for the sake of efficiency. This decision is based on a load variable that is affected by speed, however speed alone is NOT the deciding factor.
So saying >70mph just isnt correct as this "2-motor combined mode" could occur under very specific load conditons at as low ~40 mph (. As saghost said, this was just a speed used by certain GM people that were narrating to an animation that chose 70mph for a more dramatic visual effect as ICE is permitted connects to the ring gear, decreasing the speed of MG2 significantly at that higher road speed.

For more information check out THESE old threads:
http://gm-volt.com/forum/showthread....odes+operation
http://gm-volt.com/forum/showthread....e-quot&p=67812


WOT

That's a nice plot WOT. I totally understand it but.....

here's my question:

How do I put gas in my Volt??

So far I only have had to use the J1772 outlet.

[WopOnTour]

That's a nice plot WOT. I totally understand it but.....

here's my question:

How do I put gas in my Volt??

So far I only have had to use the J1772 outlet.

Haha awesome. So I guess it IS making your daily commute under 100% EV after all?
(I posted late in your main page thread congratualting you but you may have missed it)
Hope your Volt serves you well sir!
WOT

[George S. Bower]

Haha awesome. So I guess it IS making your daily commute under 100% EV after all?
(I posted late in your main page thread congratualting you but you may have missed it)
Hope your Volt serves you well sir!
WOT

I did miss it. But went back and read it. Thx WOT. Yes this car is pretty amazing in EV mode. I'm getting 3.4 mi/kwh and that's w/ A/C on and sport mode. I also enjoy running w/ traction control off so I can chirp the tires. Yesterday I went to town and back on 90 cents worth of electricity just to buy a new hat. We have round abouts here they are very fun. I went round 2 times. The Volt is a little slotcar.

Sorry for the OT



The challenge for the Volt will be this winter when we go to the desert house. That will be a 76 mile round trip with a 2000' climb up to Payson. I'm still cogitating on how to get the best MPG. Still haven't got the Dashdaq.

I need to go study some of Walter's threads.

[kj7]

Thanks for the excellent information posted in this thread. This is a topic that has always confused me.

Could someone please confirm that in no circumstance does the ICE mechanically drive the wheels (assist the motor) when the battery is not depleted?

thnx again

[saghost]

Thanks for the excellent information posted in this thread. This is a topic that has always confused me.

Could someone please confirm that in no circumstance does the ICE mechanically drive the wheels (assist the motor) when the battery is not depleted?

thnx again

In general, your statement is correct - the engine doesnt come on to assist the electric motor(s), like the PiP or upcoming Ford Energi twins. However, the Volt is a complicated car - it doesn't really take well to always or never statements.

There are three unusual circumstances that force the engine on with a charged battery (in addition to hold and mountain modes, where the driver has asked the car to hold some of the battery,) - if it is below 26F outside, it will run the engine until the coolant is warm for cabin heat (you'll see this here on the forums as ERDTLT - shortened from the message the car displays "engine running due to low temperature.") If the engine hasn't been run in six weeks it'll run for a couple minutes to lubricate things and cook the water out of the oil. If the fuel in the tank is more than a year old, it'll run until it gets down to 1/3 tank or fresh fuel is added.

Under any of these rare conditions, if the speed and power conditions above match, the engine could directly drive the wheels through the MG A driveshaft and planetary gears with help from MG B.

[WopOnTour]

In addition to what saghost has mentioned there are also certain abnormal conditions as might occur when certain faults are detected and specific DTCs set. This can result in "fail-safe" behaviors such as "Reduced Power" mode where the ICE might start up even if there is remaining charge available. Few people would (hopefully) ever encounter this of course but it still exists a possibility.
WOT

[kj7]

Thanks guys. Appreciate it.

One other questions that is not really related but I don't feel deserves its own thread:

I understand the battery management software doesn't utilize the entire pack for daily charging. I understand this is so that as the pack degrades the window can be expanded to keep range somewhat constant. My question is whether the "window" it does use is periodically redefined such that all cells of the pack are used in an even manner, or rather, is it using the same set of cells until there is sufficient degradation to merit an increase in the window?

thnx

[saghost]

Thanks guys. Appreciate it.

One other questions that is not really related but I don't feel deserves its own thread:

I understand the battery management software doesn't utilize the entire pack for daily charging. I understand this is so that as the pack degrades the window can be expanded to keep range somewhat constant. My question is whether the "window" it does use is periodically redefined such that all cells of the pack are used in an even manner, or rather, is it using the same set of cells until there is sufficient degradation to merit an increase in the window?

thnx

This is mistaken. All 288 cells, 96 parallel triplets arranged in series, are charged and discharged together at all times. The capacity/degradation thing is about how much you charge them. The Volt never pushes the battery past ~85% charged, and never discharges it below 15% charged (the engine comes on somewhere around 22%, and it is unusual to get the pack much below that point.)

Since battery wear and tear almost entirely occurs at the upper and lower ends of the charge and at high temps, the combination of the limited window and thermal management keep the battery from wearing down for a long time.

I'm still waiting to see as far as opening the window to keep range goes - Frank Weber (line manager/chief engineer for a lot of the Volt development) made a statement in about 2009 that GM had to provide the same range at end of life ad at the beginning, which (possibly with some unofficial comments from GM) has been interpreted by many here to mean GM will open the window as the battery degrades. I still think it is a rather foolish idea on an EREV (better a battery with 10 miles left than one that failed totally do to range extension,) and am waiting to see if GM did it in the production cars. As well designed and tested as the Volt is, it'll likely be a long wait.

[maynard]

We don't get all in a twit about using the CS mode in our Volt. When this car was new in March of 2011 we would get 40 to 41 mpg when driving 70mph in CS mode.I suppose that some of this driving is with the engine clutched up to assist the motor, but I sure can't tell. This year we get between 42 and 46 mpg all the time in CS mode. That is awesome. I will bet that only the Prius and the Jetta diesel do better. I guess our engine is getting broken in now. We drive all week electrically but do about 100 miles in CS mode commuting to and from our cottage on weekends.