2015 Volt Mountain Mode vs CS/Hold Mode efficiency
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Thread: 2015 Volt Mountain Mode vs CS/Hold Mode efficiency

  1. #1
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    Default 2015 Volt Mountain Mode vs CS/Hold Mode efficiency

    Sometimes, I'll know that I have quite a few miles to go before charging, and my battery is nearly empty. I've been toying with the idea of going into Mountain Mode for a few miles and letting it charge up the battery a little bit so that I can drive on electricity for a little longer. My idea is that you'll spend a couple miles with the ICE on and generating electricity, and then you'll have some pure electric miles in the battery after switching back to Normal mode. Hopefully, the miles spent in MM, plus the electric miles in the battery at the end of it would equate to more miles than the same amount of gas would have sent you in CS mode. Note, I am just driving on normal streets and highways, not mountainous roads which would actually need Mountain Mode.

    I'm wondering if the car charges the battery more efficiently in Mountain Mode since it is always running at a constant, higher rate instead of fluctuating as you drive like in CS mode. My understanding of CS and Hold modes is that the ICE kicks in at appropriate time and throttle so that the battery will just stay at the given SOC, with the car still being powered by the battery (except for extenuating circumstances where the ICE connects directly to the wheels).

    I have not done this yet, it's merely an idea, so I was wondering if anyone else had any thoughts/experience/data about it.

  2. #2
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    According to the BSFC map, the engine is at peak efficiency from 1700-2700 rpm at wide open throttle - which just happens to be where CS mode normally operates.

    The engine operation is probably a little more efficient on the mountain mode side (unless you're on the freeway at 60+, in which case the engine will rev out of the most efficient range) - but in practice that's usually offset by the increased losses from more energy being converted to electricity and run through the battery charge/discharge cycle.

    This is actually a favorite discussion topic on the forum - and a variation of it back in 2011 was what I finally joined the forum to discuss - several months before I bought my Volt. There have been a bunch of attempts to test the theory, with results that range from an almost 10% improvement through using mountain mode to significantly lower economy. Most of the time you'll just about break even with it.

    If you really want better economy, it's mostly the usual hypermiling stuff - slow down, accelerate slower, and try to avoid using the brakes at all or even much regen.
    Walter
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  3. #3
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    Yeah, it's a popular topic. I'd suggest reading through the discussions and forming your own opinion. My theory is I generally do best on a long trip by using hold mode (MM if you don't have hold) while I still have 1/2-3/4 charge. I switch back to normal when I'm about within electric range of the next stop where I'm going to charge up. My thinking is this leaves me enough charge buffer to avoid working the generator too hard (maybe off peak efficiency).

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  6. #4
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    It is unclear if MM is anything more than a variant of Hold mode where the computer, not the driver, selects the battery soc to be "held."

    MM includes the feature that recharges a depleted battery back up to the MM-maintained soc if MM is engaged after the soc is below the maintained level. Once that is done, however, is there any technical documentation available that suggests the propulsion system operates differently in MM than in Hold mode at that soc?

    If there is a difference, does that mean MM burns more gas or less gas than Hold mode when running in CS mode at the MM-maintained battery soc? Could a Volt possibly operate more efficiently if you switch from MM to Hold once the recharging has taken place?

  7. #5
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    Read this thread

    http://gm-volt.com/forum/showthread....ting+technique

    then realize that this thread plus a number of related threads were closed because this caused a great debate (Similar to the TASTES GREAT, LESS FILLING debates in the 80s). I've tried it, it doesn't work at all at saving you any range... The whole conservation of energy thing. You might be able to eek some miles if you do the right things under the right circumstances with hills and gravity involved, but I've given up. The whole concept of V------ (the word that shall not be named) doesn't work for me.

    While you are enjoying the fun, check out the Voltamorting thread from April Fools Day.

    http://gm-volt.com/forum/showthread....t=Voltamorting

    As Faux news says "we report, you decide (whether we are idiots)"
    Last edited by llninja; 05-23-2016 at 08:41 PM.
    LLninja (greenback troll #1)
    2013 Volt G1 white diamond tricoat

    If I can get the guy in the mirror under control I can be skinny and rich.
    If you don't have the money, don't buy it. Debt is hazardous to your wealth
    Hidden Content Originally Posted by doctorq Hidden Content
    "what kind of mental problem do you have? you should really get yourself checked out, are you on any type of psychotropic medications?
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  8. #6
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    Quote Originally Posted by llninja View Post
    Read this thread

    http://gm-volt.com/forum/showthread....ting+technique

    then realize that this thread plus a number of related threads were closed because this caused a great debate (Similar to the TASTES GREAT, LESS FILLING debates in the 80s).
    Or read some of these, going back to May 2010, before the car was even in production:
    http://gm-volt.com/forum/showthread....in-mode-gaming
    http://gm-volt.com/forum/showthread....Mode-Hold-mode
    http://gm-volt.com/forum/showthread....-Mountain-Mode
    http://gm-volt.com/forum/showthread....e-Extend-range
    http://gm-volt.com/forum/showthread....-Mountain-mode!
    http://gm-volt.com/forum/showthread....akes-Headlines...
    http://gm-volt.com/forum/showthread....riving-up-hill
    http://gm-volt.com/forum/showthread....-mode-this-way
    http://gm-volt.com/2010/05/05/chevy-...mountain-mode/

    I'm still not sure how the johnny-come-lately author of the two threads above got to name the mountain mode games in the minds of a lot of forum members, 5 years after we started talking about them.

    The threads weren't killed due to the arguments, but rather because the author of those threads continued to put forward his theories (over and over again in the same thread, and repeated in several other threads that were merged back together) without supporting facts/evidence and in defiance of the actual reality of the car's function and efficiency.
    Walter
    C4884 - White Diamond, purchased 10/15/11
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  9. #7
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    Quote Originally Posted by saghost View Post

    I'm still not sure how the johnny-come-lately author of the two threads above got to name the mountain mode games in the minds of a lot of forum members, 5 years after we started talking about them.

    The threads weren't killed due to the arguments, but rather because the author of those threads continued to put forward his theories (over and over again in the same thread, and repeated in several other threads that were merged back together) without supporting facts/evidence and in defiance of the actual reality of the car's function and efficiency.
    you're right, there was some name calling and finger pointing that also contributed to the closures. I think one thing that bothered a. Lot of people was the way the author of the original post invented a name for it, thus claiming that this was his original thought, and was adamant that he was right. With everyone claiming "We Are Right" (acronym became WAR). I just enjoyed the April fools joke as some forum members actually fell for it, hook, line, and sinker, including the entire boat.
    LLninja (greenback troll #1)
    2013 Volt G1 white diamond tricoat

    If I can get the guy in the mirror under control I can be skinny and rich.
    If you don't have the money, don't buy it. Debt is hazardous to your wealth
    Hidden Content Originally Posted by doctorq Hidden Content
    "what kind of mental problem do you have? you should really get yourself checked out, are you on any type of psychotropic medications?
    R:IQ $2.2M, at $1.7M proj $4.8M

  10. #8
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    Quote Originally Posted by schraitle View Post
    My idea is that you'll spend a couple miles with the ICE on and generating electricity, and then you'll have some pure electric miles in the battery after switching back to Normal mode.
    Keep in mind that the Volt display of Electric Miles and Gas Miles is not a record of miles driven using battery power vs miles driven when the ICE is running. I like to think of it like this: the Volt Electric mile mirrors the Leaf or Tesla Electric mile - a mile driven on grid electricity stored in the battery (enables one to compare AER, mi/kWh, etc.). Everything else is a Gas mile.

    In the Volt world, battery power put there by regeneration when driving on grid power from the battery counts as Electric miles when used (kWh Used = net grid power used). Battery power put there by regeneration when driving in Hold or Mountain Mode or with a fully depleted battery counts as Gas Miles when used.

    Battery power put there by using MM to recharge should also count as Gas miles when used, it is not grid power and should not be used to increase your AER stats (2011/2012 Volts have a glitch that can count use of this power as Electric miles, but the kWh Used number will not change when this power is used).

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