Volt should have no problem

The Volt is able to go 100 MPH (actually it is able to go faster, but will be limited to about 105). Don't know what kind of acceleration it will have at 75 mph, but we know that it has very good acceleration at low speeds. I presume that you know that the Volt DOES have a gasoline engine (ICE) that comes on automatically when the battery level gets to a 30% charge level. In your case it would be very desirable to plug in at work. Also, since you mentioned semi trucks, the 40 miles AER can very quite a bit based on driving habits, and drafting behind a semi might help extend the AER quite a bit.

 

Of course top speed is not the same as top sustainable speed when we're talking about an EREV with a big battery buffer. But somewhere recently I saw a driving review that said, I think, that the genset was still cycling on and off during a sustained drive at high speed (maybe 70 MPH?). If so, I'm guessing it should be able to go 80 easily and continuously until you run out of gas. Worst case is the computer might have to kick the engine up a notch to a slightly less efficient RPM.

 

The Volt is designed to cruise at 100mph (on level ground) until it runs out of gas.. obviously the genset will never cycle off at those speeds.

 

If it's a two lane highway and you need to pass semis frequently it would probably shorten the battery life some. I have no idea if it could be enough to be a concern.

 

I commute 67 miles on way 124 miles round trip. Over 90% of the commute is highway with signifcant semi traffic. Average speed 75 to 80 mph. Does anyone know if the Volt will be able to hold up in such traffic or should I make plans for a gas engine.

First, we don't know the Volt's highway mileage in gas engine mode.

My guess is 42 MPG.

In that case, a driving cycle such as yours with 124 miles of highway miles at 75-80 MPH will result in an insignificant mileage improvement that does not justify the additional cost of the Volt.

(You would have to put your driving cycle into a program/chart to predict the actual mileage you could get .)

 

First of all, the Volt will have no trouble with your trip, even if you never plug it in.

The first 40 miles will be gas free, the other 94 miles will use 2.2gallons of gas if we assume 42mpg in CS mode.. total mileage will be 61mpg.

If you could recharge it while you work then your total mileage would be 103mpg for the round trip.

You wont be able to beat either mileage, not even with a Prius... and the Volt will be a sportier, faster car. If they let you plug it in at work you can also turn on the AC or heat before you get to the car.

 

Average speed 75 to 80 mhp. Does anyone know if the Volt will be able to hold up in such traffic or should I make plans for a gas engine.

160HP is 160HP.

Is that enough? You decide. I'm sure 2-Mode EV's arn't far behind.

 

Let’s get back to the basics…
Suppose the Volt has the following numbers:

Gross weight: 1800kgs (3960lbs)
Rolling resistance coefficient: 0.015
Cd: 0.25
Frontal area: 1.6m*m

Air density: 1.247
Gravity: 9.81

In order for this car to go 70miles/h (31meters/s) it will need the following amount of HP:

HP needed to roll: 0.015*9.81*31*1800/750 = 10.94796
HP need to sustain 70mph against wid: 0.5*0.25*1.6*1.247*31*31*31/750 = 9.9065
HP lost or consumed internally (electrical+mechanical+HVAC+lights) = 10 approx.

Altogether the Volt needs about 31HP to run at 70mph on a flat smooth road, which is well within the max output of the ICE.

Now, suppose you want to pass an 18-wheeler in front of you by increasing speed to 85miles/h (38meters/s) in 10 seconds…

Motion energy at 70mph: 0.5*1800*31*31 = 864900
Motion energy at 85mph: 0.5*1800*38*38 = 1299600

Therefore, you need an extra 434700 joule of energy to pass the 18-wheeler. If this job is to be done in 10 seconds you need 43470 joule or 57.96HP every second in addition to the abovementioned 31HP making the total requirement to about 89HP. This is beyond the capability of the ICE, therefore, you must tap into the reserve energy in the battery. I do not think you can do this passing so often once you start putting your hand in the battery. If the road is uphill, do not attempt to pass.

Note: The above requirement of 89HP does not include increase in rolling resistance and wind resistance at 85mph, which should require about 20HP more than at 70mph.

 

Ah yes -- the Basics. I think we were looking for something a little more advanced...

 

You can do it a few times, but note that you wont be going uphill at 80mph all the time, and the genset will rev up to build up a reserve. Lets say the reserve is 5% of 16kwh, (or even 10%).. that is 0.8 kwh or about 1 minute reserve of extra 60hp.. how many trucks can you pass in 1 minute?.. you pass the truck doing 50mph, settle in front of him and slow down to back to 70mph.. that reserve will be built back up quickly.

If you do this long enough the Volt will PROBABLY adapt and charge up a bigger reserve. I think passing trucks will be limited at certain speeds, but probably not at 70-80mph. Something the Volt driver will quickly learn.

 

Driving cycle MPG

I know this thread is about speed capabilities but I had to run this driving cycle thru a little program I wrote that calculates the Volt's AER and CS Mode MPG.

I ran 4 cases for his driving cycle and compared them with a vehicle that gets Prius mileage.

The 4 cases are:

1) 60 MPH, 1 charge (at home)
2) 60 MPH, 2 charges (at home and at work)

3) 70 MPH, 1 charge (at home)
4) 70 MPH, 2 charges (at home and at work)

The results are

1) 58 MPG vs 51 Prius
2) 89 MPG vs 51 Prius

3) 47 MPG vs 47 Prius
4) 66 MPG vs 47 Prius

Conclusion= unchanged

for this extreme of a driving cycle (70MPH and 1 charge) you might as well buy a parallel hybrid

Slow down, charge twice and Volt is a contender.

 

I know this thread is about speed capabilities but I had to run this driving cycle thru a little program I wrote that calculates the Volt's AER and CS Mode MPG.

I ran 4 cases for his driving cycle and compared them with a vehicle that gets Prius mileage.

The 4 cases are:

1) 60 MPH, 1 charge (at home)
2) 60 MPH, 2 charges (at home and at work)

3) 70 MPH, 1 charge (at home)
4) 70 MPH, 2 charges (at home and at work)

The results are

1) 58 MPG vs 51 Prius
2) 89 MPG vs 51 Prius

3) 47 MPG vs 47 Prius
4) 66 MPG vs 47 Prius

Conclusion= unchanged

for this extreme of a driving cycle (70MPH and 1 charge) you might as well buy a parallel hybrid

Slow down, charge twice and Volt is a contender.

Do the same table in $ and cents.

What does EV operation cost? About $1 per 50 miles?
-and- $3 per 50 miles when using petro?