Will the Chevrolet Volt be a failure or a success?

Sometimes, as I've mentioned before I wish there was a way to make it use the ICE when traveling at high speed and I know the range will be well exceeded anyway perhaps to save more electricity for slower speed driving closer to my destination.

I'm not familiar with this whole "warp stealth" thing, but it changes my understanding of the more blended approach in the Prius. Why pay any penalty at all to do it when it would be more efficient to burn gas than kwh's? Sounds like a choice to intentionally take lower efficiency to increase EV range which is what you guys ride me about so hard on the Volt.

Oh well, thanks for helping me learn something new today.

 

I recall that that is what Mountain mode is for?

 

Remember the 2-mode hybrid pure mechanical path hype? When it was all said and done, the highway MPG gain was less than HSD.

It is important to look at the result, especially the real world data. The data you'll collect will be highly valuable.

 

ICE is not efficient below the 12kW (~16 hp) output. Atkinson cycle plus the EGR can do so much to reduce pumping loss. Under that power output, it makes more sense to use the battery. Higher than 16hp output (during > 62 MPH) may have the ICE blended as you would expect. Can anyone with more PHV mile experience confirm this?

I believe the choice was made because the alternative was worse (higer cost, more complex, less reliable with very little efficiency gain in return).

 

If the battery SOC is above 60%, Mountain mode won't engage. Production Prius PHV was reported to have a button to enable the HV mode. That's a better solution than the Mountain mode.

 

Without offering any real tech, 1.5hp seems awfully low. That's (barely) enough to run my one cylinder air compressor. Aside from the obvious friction and pumping loses, you have to spin the oil pump, water pump (in the case of 2009 or earlier), and alternator. Does it spin really slowly in this mode?

Have you ever cranked an engine over by hand, even with the plugs out?

 

Prius doesn't have an alternator.

At 70 MPH speed, wind resistance is the greatest loss (half of total loss). Mechanical loss is second (includes ICE, PSD, MG1, MG2, water pump and final gear) at 3.77 kW. Tire resistance plus accessory load equals to the mechanical loss.



Figure 15 in this report said mechanical loss without the ICE is 1.3 kW (MG2 @ 4,128 rpm = 70 mph). Do the math and ICE loss come out to about 2.5 kW. That's while the ICE is running (23 hp cruising). If it is not burning gas, it idles below 1,000 rpm so it should have less loss.

Keep in mind, the above figure is for Gen2 Prius. Gen3 has less mechanical loss due to the electric water pump and two shaft chain-less design, so there is less mechanical drag.

Do you know any mechanical loss figure for the Volt?

 

Mike, Prius engine in those situations does not really compress (VVTI timings change), so there is very little pumping losses. Alternator does not exist.
ICE spins around 900rpm, not more.
I have cranked several, but I believe our perception is decieveing. Cannot compare that.

If you see closely, it makes sense, because when a non-hybrid car is idling it can consume up to 1,5litre/hour. 1,5litre is roughly 50MJ -> it has absorbed that in an hour, means it has absorbed 14kW. If the efficiency for this operation is 20% (in fact it can be lower than that), it equals a power of 2,8kw delivered to drain. Now imagine it without peripherics and with very low actual pumping.

 

I should have guessed on the alternator. I even did a quick search. Don't know what I was thinking.

Great data in that report. Thanks. Reasonable analysis from both of you.

No idea on the Volt. One neat detail it does have is a variable displacement oil pump to reduce losses. Of course, it never spins its ICE with power from the MGs.

 

It does have to engage and disengage the clutch #3. That requires energy to match the speed before engaging right? If you are driving the Volt around 70 mph with the gas engine on (CS mode), you can be in either mode 2 or 4.

Does it switch from mode 2 to mode 4 if you go from 69 mph to 70 mph? Then back to mode 2 once your speed drops to 69 mph? If you hover around 70 mph, wouldn't there be plenty of clutch activity?

 

Ah, you made me look up the modes. I'm forced to renew my point that you're obsessing over the car's behavior in what most users will find the exceptional condition. I seem to be in the minority who is actually impressed with the gasoline EPA numbers the calibrator got out of the pig (it weighs about as much as my 5 series BMW wagon!) though.

Anyway, mode 2 is EV only. You're thinking of mode 3 (serial) vs 4 (parallel). Yes, it has to match revs, but it's burning gas so it can use the throttle.

No, there is hysteresis in the system. Also, it can actually switch in at any speed over ~45 where, depending on conditions, the car can be in either drive mode during CS.

If you have the patience, this detailed presentation from Pam Fletcher is pretty good although of handheld camcorder quality. Nice animated graphics show the different modes at around 31 minutes.

[ame="http://www.youtube.com/watch?v=d9-9atMw6Zs"]YouTube - ‪2011 Chevrolet Volt, Powertrain‬‏[/ame]

 

Yes and no, also I am becoming a huge fan of mountain mode.

Mountain mode sets a higher state of charge to begin CS operation (for instance if normal charge depletion is from 80% to 30%, mountain mode will set the low point at like 45% [don't know and don't care to know the exact figures]).

So if I'm on the interstate going 75 mph and knowing I'm going a couple hundred miles so trying to avoid oil consumption is moot, I'd like to switch immediately to the more efficient ICE w/ mechanical assist. If I try to do that by engaging mountain mode nothing will happen until the battery discharges down to the new low point.

Some people on the GM volt site refer to what I would like to see as a "Hold Mode" so we could preserve whatever state of charge we have when we activate it.

 

Also to add...

A starter engine gives us a good measure of how much power is drained - it revs from full stop to 250rpm-500rpm.
In When I try to start my engine, I hear the starter... — Yahoo! Autos
i got this:
"A good starter should normally draw a current of 60 to 150 amps, depending on the size or power rating of the starter."

That equals to 720W up to 1800W.

 

on topic:

Read that May 2011 Volt sales don't step up...
According to Wikipedia, but links got only to April sales/deliveries, in May more 481 Volts saw the light.
That gives a total of 2510 sold in half a year.

Seems a bit low, now when the crude oil is so high...the Volt market should be "thirstier than ever"...
I wouldn't like to be in their pants when competition arrives...

 

Are sales supply limited or demand limited?

If the waiting lists and premiums over MSRP are gone and they start having to offer incentives, then it probably is a problem going forward. On the other hand, I bet they've sold about as many Volts this year as other less popular hybrids like the Highlander, Altima and Civic. I think they were selling more than the Leaf last I checked, too.

 

GM has production and sales figures on the right side of GM News - United States - News.

You might also want to look at the sales numbers from the RHS of Opel Media - Europe - News (yeah yeah, it sales Opel, but these are US sales. Can't find the US version of the page.)

 

That has never been true, but the numbers confused the pundits because Nissan has been sending only a trickle of its production to the US. From this most recent reported month of May, even just US LEAFS have eclipsed total Volt production and sales for the same time period.

 

I vote yes for failure. Is it still too late to vote?

 

Hey, easy man, in this forum, we host some Volt guest members and they need to feel right at home!

 

I would have no idea how to determine if those numbers indicate the sales are limited by supply or demand. Usually, if the car is selling at sticker or above, I assume demand is good compared to supply.

So I thought wrong, then. In the USA, what are the total sales for Volt and Leaf so far? Are they comparable?