[ad#post_ad]GM's director of hybrid and electric powertrain engineering, Larry Nitz, took time out of a Volt prototype fleet 99% calibration drive in the mountains, valleys and roads of Southern California to take some questions from journalists.
In this teleconference, which I attended, he made the announcement that in addition to a sport and normal mode, the Volt will also have a mountain mode operation.
This will be a driver-selectable option that acts to ensure the battery has a bigger reserve than usual, and can be put into effect either during EV or extended range driving.
Nitz explains the Volt's engine is "downsized," meaning it can only generate 55kw of power whereas the electric motor can output 110 kw, relying on the other half of its extended-range power needs from the battery.
In some circumstances such as a steep high acceleration hill climb then, the car's "performance could deteriorate."
To offset this, the "savvy" driver can choose to place the car into mountain mode when they anticipate the need to climb long steep grades. "If you wait until you get to the hill its too late," says Nitz.
If the car is already in EV mode when mountain mode is selected, the setpoint of battery state of charge where the generator would go on is raised to a higher level. This would then allow the motor a larger buffer of power to utilize to climb the mountain vigorously. If the car was already in extended range when the mode was selected it would allow itself to charge to a higher level than in normal mode.
Nitz admitted given an infinitely long hill, the extra reserve would be used up and performance would once again degrade, but he said the mode was designed to work fully in 99% of driving situations. He also said EV range would be reduced if mountain mode was activated in EV mode, but wouldn't say by how much.
Nitz said that mountain mode could be turned off at any time the driver chooses, and that this feature will indeed be available on the first generation Volts to be launched at the end of this year.
On the flip side, Nitz also confirmed that when going down a steep grade the battery would be allowed to fill completely to recapture all kinetic and potential energy. Once full, however, the car would have to dissipate power.
The Volt team is 99% finished calibrating the car and is extremely pleased with noise, harshness, and vibration characteristics.
Regular readers may remember a post here in August 2008 . I discussed Volt performance with Chief engineer Andrew Farah on mountain climbs. Readers at the time actually suggested a manual mountain mode in the forum , and the comments, actually referring to it as a mountain mode.
Whether GM used our suggestion or figured it out themsleves I don't know. I do know when I asked Nitz if he could go back to January 2007 knowing what he knows now, would he have done anything differently, and he responded he would not.
You can hear the whole teleconference here: