[Fulgerite]

So I think I know the answer to this question... But I thought I would ask anyway.

I am planning a trip to lake Arrowhead for the 4th. I live about 96 miles away from Lake Arrowhead. The last 17 miles of the trip will be climbing the 6,000 foot grade to the summit.

So here is my question:

1. Is it best to turn on Mountain mode at the beginning of the trip?

2. Is it better to turn on Mountain mode about 10 miles before the grade?

3. Does it matter at all?

 

[Skotty]

I would turn it on at the beginning of the trip and leave it on. Remember, if you stop anywhere on the way and turn the car off, you have to turn MM back on again.

 

[Noel Park]

Well I dunno, I've had my volt for 16 months and put 26K miles on it, and I've never used MM, LOL. I've never taken it over Tejon Summit yet, but I have gone over the Cuesta Grade and Conejo Summit and it just drove like a regular car without the use of MM. It would be neat if you could give us a report on how it works out.

 

[ShannonVolt]

I believe GM recommends appx. 15 miles before you reach the mountain. I think that's what the manual said.

 

[tboult]

From an efficiency point of view you want to do it before you get to 15miles of EV range, otherwise it must "recharge" the battery... Recharge can be efficient if you are going down hill, but very inefficient if you recharge going
uphill.

As already said, I recommend you just start in MM mode.

 

[Fulgerite]

I also think the best strategy is to put it in MM at the beginning and just enjoy the drive.

 

[2BeLivingGreen]

Totally agree MM from the beginning.

The interesting thing about the VOLT is that MM (short of having a HOLD mode) gives the driver alternative strategies to optimize the energy. Just another feature that makes conventional cars very crude and limited in their energy usage.

 

[PatsVolt]

GM's 15 mile recomendation is because that is the aprox size of the MM buffer. If you allow it to drope below that level, you will incure more gas usage to regenerate the buffer. In fact I always use MM when on long distance trips greater then my EV only range. Reason for that is that you will run out of EV range farily quickly on the highway and it is nice to reserve some EV range for when you leave the highway. Also you if you go on trips like I do, some steeps grades will be on my route.

Pat

 

[tboult]

GM's 15 mile recomendation is because that is the aprox size of the MM buffer. If you allow it to drope below that level, you will incure more gas usage to regenerate the buffer. In fact I always use MM when on long distance trips greater then my EV only range. Reason for that is that you will run out of EV range farily quickly on the highway and it is nice to reserve some EV range for when you leave the highway. Also you if you go on trips like I do, some steeps grades will be on my route.

Pat

Actually I think the 15miles it is because it takes about 15min, from minimum SOC, to reach full mountain mode SOC, (which if you are going up hills will look like 11-miles of range).

 

[Paul*]

Moutain mode at the beginning or before you reach 15 miles left on the battery (either way produces the same result as long as you don't forget to turn MM on). Remember to turn mountain mode off at least 10 miles before you reach a charging station. That way you can finish your trip on electricity.

 

[ShannonVolt]

GM's 15 mile recomendation is because that is the aprox size of the MM buffer. If you allow it to drope below that level, you will incure more gas usage to regenerate the buffer. In fact I always use MM when on long distance trips greater then my EV only range. Reason for that is that you will run out of EV range farily quickly on the highway and it is nice to reserve some EV range for when you leave the highway. Also you if you go on trips like I do, some steeps grades will be on my route.

Pat

I haven't experimented with MM yet, when I eventually drive my Volt on the interstate and I have full EV power I can leave in mountain mode for the duration of the several hundred mile trip until the battery is fully charged up again? Is this correct? Seems like MM is similar to the hold feature.

 

[tboult]

I haven't experimented with MM yet, when I eventually drive my Volt on the interstate and I have full EV power I can leave in mountain mode for the duration of the several hundred mile trip until the battery is fully charged up again? Is this correct? Seems like MM is similar to the hold feature.

Yes can leave it on all the time, but it won't fully recharge. Hold and MM are somewhat similar but distinct.


The Hold feature will Hold the battery at any given level (even completely full). MM will "hold" it at a SOC charge worth about 11 miles of EV range -- and will use the added battery as a buffer to allow high-speeds on steep hills. Also MM will recharge an empty battery to that added SOC range

We don't yet know for use how hold will manage the buffer but it will not use the engine to recharge.

MM is a poor-early-adopters Hold mode until we hack the car.

 

[AZ EV Driver]

If you turn on MM at the beginning, then you will "reserve" some of the cheap grid energy for the big climb. If you wait to activate MM then the ICE will have to work extra hard to generate and store the energy by burning not so cheap gasoline. It is more economical to take advantage of the grid energy. Just don't forget that you will have approx. 15 miles of reserve EV that can be used for cruising at the top of the mountain, or saved for your return trip which can be combined with the regen energy coming back down the hill.

VIN # B0985

 

[Slapshot28]

I haven't experimented with MM yet, when I eventually drive my Volt on the interstate and I have full EV power I can leave in mountain mode for the duration of the several hundred mile trip until the battery is fully charged up again? Is this correct? Seems like MM is similar to the hold feature.

I'm not sure if you really meant "until the battery is fully charged up again," but if read literally the answer would be, "No, MM targets about 33% of SOC, or roughly 15 miles of pure EV range."

 

[PatsVolt]

I haven't experimented with MM yet, when I eventually drive my Volt on the interstate and I have full EV power I can leave in mountain mode for the duration of the several hundred mile trip until the battery is fully charged up again? Is this correct? Seems like MM is similar to the hold feature.

No it will not fully charge the battery, it will only keep the battery at the 15-17 mile buffer limit. But you can use it like the "Hold" mode in the Opel. Using the MM keeps some but not all the battery in reserve, for you to use as you need to. I useally run the gas tank to it's reserve before I refill and the battery reserve acts as my real reserve or for just using EV mode for off highway usage like getting off the highway to eat or go to a Motel. I do feel that I get better milage, but I have not proven that to myself. When in MM the car will act just like in CS mode, although, it will provide more power when you need it from the battery if needed, which is the main difference.

Pat

 

[Bob G]

In my experience, mountain mode takes about 20 minutes to "catch up" from a discharged battery to the buffer set point (33% state of charge sounds about right.). During this time, the engine is working double duty (charging the battery *and* providing energy for propulsion), so I don't expect full performance. Also, the buffer set point is more like 10 or 11 miles of indicated range in my car (not 15). Maybe the reason is because it is cold, dark, wet, and hilly here in Seattle, but getting even 40 miles of electric range is rare for me.

When I go on long trips over mountain passes, I keep it in mountain mode from the beginning of the trip. Using the gasoline engine to "catch up" adds unnecessary energy conversions, so it is not as efficient as just using the grid energy for the buffer.

 

[ShannonVolt]

Ready for more stupid questions? What does CS and SOC stand for?

 

[tboult]

Ready for more stupid questions? What does CS and SOC stand for?

Sorry..
Charge Sustaining (i.e. hybrid mode running on ICE but keeping a approximately constant SOC).

State of Charge (i.e. battery level. The battery guage in the car us usable SOC from 0-100%. The actual SOC in the battery for that usable range is about 21 to 86.4.. i.e. it only uses about 65% of the battery).

 

[saghost]

Ready for more stupid questions? What does CS and SOC stand for?

CS - Charge Sustaining - basically, when the battery is "drained" and the engine comes on. Though actually the battery isn't completely dead and still has a role to play, and at times (decelerating, slow speeds, sitting at a light) the engine will be off. As opposed to CD - Charge Depleting - the mode where the car is driving off of wall power stored in the battery.

SoC - State of Charge - the current level of the battery as a percentage. The Volt keeps the battery between ~86% on the high end and 15% on the low end - but the engine comes on in normal and sport at ~22% and tries to keep the battery there, giving the car around 1 kWh of usable energy to handle acceleration and hill climbing. In MM, it adds another 3-3.5 kWh to this buffer - enough power to take it up any mountain in the country at higher than limit speeds, GM says.

 

[ShannonVolt]

Thank you guys! I'm glad there are still some smart folks in this world.