A Review of the Chevy Volt Charge Sustaining Mode

Interesting comments for the reporters.

From All Cars Electric:

Two lucky, select journalist have no had the chance to test the Chevy Volt in charge-sustaining mode and although the vehicle is still not perfect, the overall review from Lindsay Brooke of the New York Times is positive and enlightening.

Brooke was one of only two journalists to try out the Volt's charge sustaining mode and he wrote up a full review of his experience driving the vehicle during the transition. His piece ran in the New York Times under the headline of "For the Volt, How's Life After 40 (Miles)?. Some excerpts are posted below.

Though Brooke's noted that the vehicle is highly refined and praise many aspects of the car, there is still some work to be done in charge sustain mode and the transition is not as seamless as GM hopes for. GM will continue to refine this aspect of the vehicle prior to production.

As Brooke writes," Like other reporters, I had already driven Volt prototypes in the battery-powered mode, and they were predictably smooth and silent. But for eventual Volt owners, a crucial - and so far unanswered - question is how the car will perform when the battery's charge is depleted and all electricity is provided by an onboard generator, driven by a gasoline engine, that has no mechanical connection to the wheels."

At this point during the test drive the vehicle is nearing the zero mark on its electric range meter gauge signaling the need to enter into charge sustaining mode. Surprisingly, Brooke's note a seamless transition. As he said, "With the dashboard icon signaling my final mile of range, I point the Volt toward a hill and wait for the sound and feel of the generator engine's four pistons to chime in. But I completely miss it; the engine's initial engagement is inaudible and seamless. I'm impressed."

Somewhat stunned by the seamless transition, he continues down the track for a few hundred yards and then disappointment set in. Brooke said, "The engine r.p.m. rises sharply. The accompanying mechanical roar reminds me of a missed shift in a manual-transmission car. For a moment the sound is disconcerting; without a tachometer, I guess that it peaked around 3,000 r.p.m. A few times later in our test, the generator behaved in similar fashion - too loud and too unruly for production - but there is time for the programmers to find solutions."

At this point, according to GM's Tony Posawatz, the vehicle sensed that its state of charge was low and it was trying to recover as quickly as possible. This aspect will receive additional fine tuning. As Posawatz said, "The charge-sustaining mode is clearly not where we want it to be yet.

Aside from complaints about the charge-sustaining mode, Brooke came away impressed with the overall vehicle. He closed by saying, "Throughout my test, the prototype behaves admirably. At its current state of development, the Volt is an extremely refined vehicle."

So there it is. One of the first drives and reviews of the prototype Chevy Volt in charge sustaining mode. GM will continue to tweak this transition until they get it right and additional reviews are sure to follow.