Quote:
Originally Posted by zete
There's been a correction to the correction. Not sure if it's been posted elsewhere, but the generator does charge the battery, but it's not its primary role.
 As the Volt Turns.
According to Lauckner, the battery will receive power from the gas engine when load conditions are light (as in, not under acceleration). When the battery comes back up to a certain level of charge (that figure is still the subject of development at GM), the gas engine can cycle off and the Volt can run for an unspecified period on the stored battery power.
Thus, if through conservative driving one stores up enough juice, it'd be electric only again. Nifty. |
This isn't any revelation as it has been implied in what we already knew. We have always been discussing how the Volt when running the ICE would use the battery as a load lever and I quoted in my useless details:
Quote:
Originally Posted by MonaroSS
Not so fast. Details count.
Larry Nitz said they were able to raise the cycle points from 30-80 to 35-85, but able to dip down into the 30+ range. Add to that he said the engine at 50kW (67hp) "does not have the full power to do the dynamic response [but] that the electric side can, so you do have to depend on the battery".
|
You don't need some journalist to tell you that if the Volt relies on it's battery for 'dynamic response' which the ICE cannot provide, then it must draw down power out of the battery down below it's charge sustain level. So by definition it must at some point recharge the battery back up to that charge sustain level if it is to avoid a deep discharge (if its not close to home) that may otherwise damage the life of the battery.
The only time that it can avoid that is if it 'knows', as Lutz said and which I also quoted, how far it is from home:
Quote:
Originally Posted by MonaroSS
So you can probably conclude the meaning of what Lutz said about the system being smart enough to know if you are close to home and the battery not needing to recharge.
Given the battery has 16kWh, but only accesses 8kWh during the normal cycle, if it dipped down below 35% to say 32.5%, for the 'dynamic response' the engine can't provide after charge sustain mode is reached, then this amounts to an equivalent energy consumption to a range of 2 miles of driving.
If 8kWh gives 40 miles then 0.4kWh, which is the differential between 32.5% and 35% SOC, gives 2 miles. To recharge up to the sustain level from there would take far more than 2 miles even if the engine is running constantly at it's 50kW maximum. Given that after providing driving power it has a average surplus of 20% then it would take 10 miles driving to get back to the 35% sustain level. But if the computer knows you are not that far from home then it can leave the battery at the sub 35% sustain level and let it be recharged on plug-in.
|
And the most likely time that the ICE would cycle off is when the Volt knows it is close to home and it is better to wait to recharge the whole battery up to full in one go than to add a little recharge up to the charge sustain level.
