The Chevy Volt uses grid electricity stored in the battery to drive Electric Miles. Hold Mode can be used to "save" some grid power for later use. Once you fully deplete the battery, you won’t have any more grid power in the battery until you plug into the wall. No grid power, no Hold Mode.

Once you fully deplete the battery, you can switch to Mountain Mode to use its "feature" that will rapidly recharge your depleted battery to the MM-maintained state of charge (~2 bars for a Gen 2, ~4 bars for a Gen 1 Volt) using a small amount of extra gas (less than 0.4 gallons for a Gen 1). MM is designed to maintain a larger Extended Range Mode buffer of battery power that can be "borrowed" if needed when driving in high power demand conditions (such as when driving fast up a mountain road).

Once MM has recharged the battery to the MM-maintained SOC, the car operates much like Hold Mode, keeping the SOC at that point. If you switch to MM as you start driving or any time before the battery SOC has dropped to the MM-maintained level, the car will remain in Electric Mode until that MM-maintained battery state of charge level has been reached. It will then switch to MM and use no more gas than it would in Hold Mode.

Note that if you use MM to recharge a depleted battery while driving, this MM-recharged battery power is NOT "grid" power. If you then switch back to Normal mode, the motor will use the MM-recharged battery power to propel the car, but the distances will register as Gas Miles (you used gas to MM-recharge the battery).

If you recharge your depleted battery using MM there is really no reason to switch to Hold Mode. MM is, in effect, a "hold" mode at that specific state of charge level.

If your goal is to artificially inflate your ev mileage and deflate your MPGcs gas mileage numbers by using MM-recharged battery power to drive Electric Miles, you can do that by turning the car off and back on again after MM has recharged the depleted battery.

When the car is restarted, the computer will recognize the battery state of charge is above the normal switch to gas level and will count the use of that battery power as Electric Miles. I suppose you could now use Hold Mode to "save" this power for later use.

You will note the kWh Used on the energy usage screen will not increase as you use this power (it is not grid power). The MM-recharged battery-powered miles will add to the total Electric Miles without using any grid power and reduce the total Gas Miles without reducing the Gas Used numbers.

 

excellent explanation wordptom ... it makes sense. My next question is: how the hell did you figure this out? were you an engineer on the volt team?!?

 

Not a Volt engineer, just someone who has been driving my 2012 Volt for 7.5+ years now, since back in those days when we were all new at driving on electricity and trying to figure out how the Volt worked... questions about Electric vs Gas miles quickly arose and were discussed... and, I might add, the 2011/2012 Volts had no Hold Mode (and the 2011 Volt had no kWh Used on the energy usage display!).

Clearly, the energy usage screen on the center console was designed to provide feedback on the Volt’s performance for two separate operations: when running as an electric car and when the range extender was in use. In Electric Mode, the Volt uses grid power (kWh Used) to drive Electric Miles. In Extended Range Mode, the Volt uses gas (Gas Used), and those distances are then recorded as Gas Miles to provide a means of calculating your gas mileage.

It’s important to keep this in mind: some "gas miles" are actually battery-powered electric miles. If you create some regen while driving downhill in Hold Mode or with depleted battery, it recharges the battery a little. When you then reach level terrain, the engine may shut off and the motor will use up that regen battery power, and the battery-powered distances will be recorded as Gas Miles. Lots of people don’t necessarily notice when their engine turns off and on as they drive their Volt in Extended Range Mode.

The regenerative braking system works in all driving modes, so you may create some regen in any mode. Regen you create while in Extended Range Mode and then use is credited to Gas Miles. Any created while driving in Electric Mode and then used is credited to Electric Miles.

 

I'm pretty sure if you had pulled over and turned the Volt off, waited a few seconds, and turned it back on, Hold mode would have worked. The system would see those 2 bars of battery left and Hold mode would have not been grayed out.

 

Happened to me the other day on Gen I. Was travelling in MM, full 40% charge, went to shift to hold, it was greyed out went through the list again, hold was there but wanted to travel the rest of trip in normal so cycled it through to normal. Didn't have to turn car off to reset. Under certain circumstances it will be greyed out it appears but is only temporary if you cycle through again, at least it did for me.

 

One possible explanation: you switched into Mountain Mode before the battery was fully depleted (say, with 1 bar of grid power left), and MM then recharged the battery to the ~4 bar level. Hold was greyed out because you had used MM to recharge the battery with some non-grid power, but by cycling through Normal, the computer was able to recognize the remaining grid power, and so the ability to switch to Hold was again available because you still had some grid power in the battery to "hold."

Because you wanted to drive in Normal, you didn’t have a chance to observe how many bars would have been "held" if you used Hold Mode (i.e., the 4 bars maintained by MM, or just the 1 bar of actual remaining grid power?). I suspect that after switching to Normal, you did not view the energy usage screen to see if the next few miles/km you drove were recorded as Gas miles/km while you used up the MM-recharged battery power and then switched to Electric Miles/km when the SOC dropped to the remaining grid power level... Or if the distances were instead recorded as Electric without increasing the kWh Used until the SOC dropped to the remaining grid power level...

 

You can go from MM to NORMAL ... but at MM completing it battery recharge cycle is a hold cycle too, like the previous poster noted.

Its a quirk of electronic engr.

 

That sounds normal to me. Did you try switching into Normal for a few seconds, then switching from Normal to Hold? That might have worked. Otherwise you could have left it in Mountain and achieved the same behavior as Hold, so this is not really a problem.

 

Barry: I did try switching, wouldn't work ...

But, last night after charging for a 1/2 hour, I had to run another errand and wahlah! The HOLD was back and available...

thanks all for your responses ... learned something new today about my volt !

 

At 18 degrees. The ERDTT mode was probably active. On my 2013, Hold is not available when ERDTT is running. Little software glitch. It happened to me. Was about to switch to hold mode when ERDTT started. Hold was greyed out until the outside temp raised a little and ERDTT shut off. Hold was available again.