[EvenSimpler]

hello, I recently took a longer trip than my usual <20 mile commute which gave me the chance to use the hold mode. the trip was about 85 miles each way, so my plan was to split the miles evenly between full electric and hold mode. however, my electric range would drop sharply on inclined roads. I would lose about 2 miles of range when driving for no more than a mile. so to preserve the electric range as much as possible, I would switch to hold mode when the electric usage would go above 20kw, and would switch back to normal mode when below this number. my logic was that the car ran more efficiently on gas when a little more power was required. I have no idea if this is true or not . when the electric usage rose above 20kw and remained there for some time, I switched to hold, and when the road flattened a bit, I would switch back to normal. I did this throughout the entire trip. I'm not sure if this is the correct/efficient way of using hold mode? would it be best to stay in hold mode until the remaining distance of the trip equals the electric range? or is switching back and forth a good idea?

some pictures of the end result:

 

[hellsop]

hello, I recently took a longer trip than my usual <20 mile commute which gave me the chance to use the hold mode. the trip was about 85 miles each way, so my plan was to split the miles evenly between full electric and hold mode. however, my electric range would drop sharply on inclined roads. I would lose about 2 miles of range when driving for no more than a mile. so to preserve the electric range as much as possible, I would switch to hold mode when the electric usage would go above 20kw, and would switch back to normal mode when below this number. my logic was that the car ran more efficiently on gas when a little more power was required. I have no idea if this is true or not . when the electric usage rose above 20kw and remained there for some time, I switched to hold, and when the road flattened a bit, I would switch back to normal. I did this throughout the entire trip. I'm not sure if this is the correct/efficient way of using hold mode? would it be best to stay in hold mode until the remaining distance of the trip equals the electric range? or is switching back and forth a good idea?

some pictures of the end result:

It's fine, but you're probably over-thinking it. Your second option, switch back when you're within range of your charger again, is a reasonable way to manage things. Since you live someplace with hills, you may want to clear some of a charge setting out, before turning hold mode on, because having the headroom to charge will make the speed-holding regen better one downslopes. ('L' mode cruise control does a dandy job of NOT running away down hills, but every thousand feet you drop is nearly a kwh and if you've already got a full charge, there's no place to save it.) But that's about as far as actually MATTERS more than a few percents.

But put a couple of gallons in there before you try it. Ari can get away with that kind of thing -- anyone else is a mere mortal and will eventually strand himself somewhere inconvenient.

 

[16513]

If you don't mind being glued to your mode switch you probably can achieve closer to ideal efficiency, but for me this is way too much work. I use speed criteria here in the flatland: fast:hold; city/suburban: battery. I do like to plan ahead on longer trips sufficiently to use that last kilowatt as I pull into my driveway. On a recent trip to Big Bear I ran my battery down to 20 mi. on the uphill leg, switched to hold until descending, where I got almost a full charge back. 230 mi., 3.1 gallons.(a mountain climb typically shows about 30 mpg; freeway in traffic: 45-50 mpg)

'16 Volt, 19,600 mi.

 

[scrambler]

Switching between electric and hold really does not have anything to do with efficiency.
The reason to use hold mode is mostly to control where you are being clean and where you are being dirty.

If I know my trip is longer than the battery range, I use Hold mode to make sure that I will run on battery inside cities, and reserve my gaz mode for the less populated areas.

As far as efficiency, it is always Less efficient to use Gas than to use just electricity.
(A gas engine is less than 30% efficient, an electric motor is over 90%)

Going uphill uses more energy than going on flat, but it is as less efficient for pure electric mode as it is for Gas. Given the inherent inefficiency of gas, it is probably even less efficient in gas mode.

So the reason for switching to hold is not related to an efficiency quest, but to how much electricity you are trying to save for the time you want to be using it. If going up that hill is going to use all your electricity and you would rather keep that for later in the trip, then use gas, but if not, no reason to switch there.

 

[llninja]

One of the dangers of constantly switching between hold and normal is that you might miss the mode button and accidents;let press the power button twice, thus putting yourself into a dangerous situation untimyou figure out how to get the car started again while moving. I typically just drive, use hold for when I want to force a fuel burn either for heat or highway driving. One other trick on highways in hold mode is to be in hold and while going down hills, it will add bars to your battery above where you last went into hold mode. If you switch to normal then back to hold you have effectively reset the hold level to the higher level.

Whatever you do, make sure you burn off all your battery before arriving at your garage - I have on more than once occasion left it in hold mode all the way home arriving with way too much battery left.

 

[Loboc]

I usually don't use hold unless on a way longer trip. I try to preserve my EV mode for city/town streets. For something this small, I just leave it in normal mode (Tour on ELR) and let the car decide.

Hold on my '13 Volt did seem to work smoother than CS mode. It didn't rev the engine as much to catch up. On ELR, the Bose sound control makes it seem like EV all the time, so, I am less likely to even think about it.

And yes, I have left hold on too long and wasted gas by arriving at the end of the trip with EV range left.

 

[Taser54]

On trips exceeding 20 miles, I use hold mode for interstate driving and keep the battery for local or stop and go driving.

 

[wordptom]

Generally speaking, you drive further on a given amount of battery power by driving slow, and generally speaking, you drive further on a given amount of gas while driving at constant highway speeds instead of while driving in stop and go, slow city traffic. The Volt is a duel-fuel vehicle, so switching to Hold whenever your speed goes above 40 mph, saving all the battery for the better efficiency of slow speed driving, and switching from Hold to Normal to avoid using the gas engine for stop and go, slow speed driving, should increase the overall efficiency of your Volt by maximizing both ev mileage and gas mileage.

Hold mode, introduced in the 2013 Volts, has made it increasingly acceptable to drive a Volt using gas, supposedly because you’re saving the battery for city use. There’s only so much flexibility in the ev miles you get from a full charge, and thus the additional ~5 ev miles you can get by careful use of Hold on a trip beyond battery range allows you to replace 5 gas miles with 5 ev miles, reducing your trip gas consumption by perhaps one pint. If you switch back to Normal too late and arrive home with some remaining battery power, that’s not wasted, but remains available and shortens the time it takes to recharge from the grid.

Hold mode allows you to drive an all-electric car around town, while also allowing you to drive across country at ICE-car refueling stop speeds. Or you could think of your Volt as an electric car, and allow it to slip into Extended Range Mode only when it must because the battery is depleted.

 

[scrambler]

Generally speaking, you drive further on a given amount of battery power by driving slow, and generally speaking, you drive further on a given amount of gas while driving at constant highway speeds instead of while driving in stop and go, slow city traffic. The Volt is a duel-fuel vehicle, so switching to Hold whenever your speed goes above 40 mph, saving all the battery for the better efficiency of slow speed driving, and switching from Hold to Normal to avoid using the gas engine for stop and go, slow speed driving, should increase the overall efficiency of your Volt by maximizing both ev mileage and gas mileage.

Juts to be clear Using the battery is Always more efficient than using the gas engine. So unless you know the battery is not going to be enough to complete the trip, switching to hold is Always less efficient than staying on battery.
But if you have to use some gas because the battery is not enough, then the optimal time to use that gas is indeed on segments of constant sustained speed, like highway driving.

... If you switch back to Normal too late and arrive home with some remaining battery power, that’s not wasted, but remains available and shortens the time it takes to recharge from the grid.

If you used Hold, and at the end of your trip you have battery left, the left electricity is not lost, but you did waste some money, as you used a much less efficient mode (gas) while you could have used a more efficient one (Battery).
That said the amount wasted is likely marginal

 

[wordptom]

I fully agree with what you’re saying, scrambler, but when thinking in terms of the next generation of electric cars, I’m thinking that ubiquitous and convenient ev recharging infrastructure that enables "recharging at ICE-car refueling speeds" is still a long way off, and will remain a handicap for car sales in the near future... unless the viewpoint is modified to promote vehicles that are "all-electric town cars" (i.e., the battery range will cover all in-city driving for most drivers) and gas hybrids on the road, retaining the ability to not need recharging when used for long business trips or family vacations. Many Volt drivers now don’t really mind using gas on the freeway if it means they can drive around town on battery power. Such "duel-fuel" vehicles would be intended to run on battery power around town and gas on the highways over the long term of ownership, with less regard to maximizing percentage of driving done using the more efficient electric motor... think of a Usage Screen that displays only "running on battery power" miles vs "ICE is running" miles, with the kWh and Gas Used recorded elsewhere!

 

[jbakerjonathan]

Based on your energy screen, I would say that you did quite well in squeezing the most miles per energy source. You went 54.6 miles on 11.5 kW; that's 4.7 miles per kWh. You went 47.8 miles burning 0.89 gallon of gas; that's 53.7 mpg. You don't say how fast you were driving, how inflated your tires were, how new the tires are or if you used Cruise Control. You didn't tell us if you used the Climate Control or what the outside temps were. You didn't tell us how many miles are on the odometer, whether you used premium gas or what year your Volt is. All these data are pertinent to an evaluation of your efforts toward efficient driving.

I have a 2014 and the best I have done without unusual effort (a la your trip) has been 5.6 miles per kW (trip distance was 59.2 electric miles at 45 mph or less using CC) and 51.1 mpg (trip distance was 104 miles with 49 miles using ICE at 60 mph on CC). In 41,450 total miles my average is 4.4 miles per kWh (10,907 miles electric) and my ICE mpg average is 37.9 (30,543 miles in Charge Sustaining mode). I do road trips across the country and never plug in to recharge when on those trips. I use AC on those trips. I get an average of 42 mpg for my road trips and use only 91 octane gas. I inflate my tires to 43-44 psi. I use CC whenever I can.

 

[srmarti]

I think the Op's method requires too much attention playing with the mode switch. That attention would be better spent on watching the road and driving the car. The method I use on trips substantially longer than the electric range is use the hold mode for the highway portions and save the battery for lower speed use. If it's several days trip without charging opportunities, a tend to keep about half charge until I'm within range of my next charging opportunity. My gas mileage tends to be 38-42 mpg even on rather short trips doing this. I don't know if it's the absolute most efficient way to drive, but it works for me and doesn't require me to be constantly fiddling with the mode switch.

 

[VoltenRock]

The most important thing is to NEVER pull into your driveway with any remaining EV miles if using hold mode and going beyond EV range.

I've "misjudged" (by doing a better job with efficiency than the range estimator thought I would) and pulled into the driveway with 2 miles left. THAT is wasteful.

Now, I'll drop out of hold when my range is about 3 miles LESS than remaining distance. It gives enough of a buffer.

 

[jsmay311]

My intuition is that this method would be particularly inefficient, given that the engine is typically less efficient when running for brief stretches. But I guess that'd depend on how long the engine is off between running and how much it and the cat converter cool off.

And given how good the results were, maybe I'm completely wrong. In fact, those numbers are almost unbelievably good. Did you charge mid-trip, or do some kind of hypermiling? 186 miles on one charge and only 2.2 gallons seems (almost) impossible, especially if you were using gas specifically on the inclines.

 

[Neromanceres]

As another note. A gas engine is very inefficient when it's cool or cold. A gas engine only runs reasonably efficient when it gets up to operating temperature. It can take several minutes for a gas engine to reach operating temperature.

Switching between modes might not let the gas engine get to operating temperature for very long and might not be great for overall efficiency.

 

[ampera_jed]

Depends what you mean 'efficient'?

No, it is not always more efficient to run electricity. Sorry.

The engine will run at around 35% thermal efficiency, and then you also get the same again, around another 35%, rejected as heat into the water coolant. So if you use all of the heat for the cabin, then you are getting 70% efficiency with around 30% exiting from the tailpipe.

If you burned that fuel in a power station to make electricity, you'd probably only be looking at 40% or so efficiency.

Obviously, if the electricity was all hydro power then that's great.

If it is all coal, then it stinks.

I use hold to heat the car up. Once I have burned enough for warmth to come through I'll shut it off until it goes cold then start it again. This way, all the waste heat ends up in the cabin heater matrix and not in the front radiator where it is literally wasted.

If you just let the engine run in one long hold mode, then the engine will hit the temperature at which the thermostat opens and the coolant goes to the front rad, wasting that heat. At this point the engine is also hotter than if you shut it off earlier than that, so Newton's rate of cooling also applies, and again you lose more heat.

 

[msujdog]

I use hold to heat the car up. Once I have burned enough for warmth to come through I'll shut it off until it goes cold then start it again. This way, all the waste heat ends up in the cabin heater matrix and not in the front radiator where it is literally wasted.

I'm with him. For a long trip -- especially this time of year -- I'll run the engine right out of the gates to warm the car up. Remember, you're graded on two scales for your driving -- driving efficiency and climate efficiency. If you can use Fan Only for your entire drive instead of Comfort, you're saving 90% more electricity for propulsion purposes than comfort. I'll switch back and forth every 10 miles to burn up my electric buffer while still keeping the engine running long enough to warm up the cabin.

 

[EvenSimpler]

One of the dangers of constantly switching between hold and normal is that you might miss the mode button and accidents;let press the power button twice

those were my thoughts exactly after switching to hold mode for a few times. I could have easily hit the power button by mistake and caused the car to turn off while going at a high speed on the freeway. I remember thinking that I would not know how to turn the car back on without pressing the brake pedal. Imo, the placement of the mode button right next to the power button is a poor design.

switch back when you're within range of your charger again

this was the original plan, but because the electric range is so heavily dependent on the terrain (among other things), I would not have made it to the destination if I had not switched over. I would have ended up using gas on the streets.

If you don't mind being glued to your mode switch you probably can achieve closer to ideal efficiency, but for me this is way too much work.

yes it's a lot of work and is probably dangerous eyeballing the dashboard that much rather than the road, but I will admit it was a very engaging drive!

Based on your energy screen, I would say that you did quite well in squeezing the most miles per energy source. You went 54.6 miles on 11.5 kW; that's 4.7 miles per kWh. You went 47.8 miles burning 0.89 gallon of gas; that's 53.7 mpg. You don't say how fast you were driving, how inflated your tires were, how new the tires are or if you used Cruise Control. You didn't tell us if you used the Climate Control or what the outside temps were. You didn't tell us how many miles are on the odometer, whether you used premium gas or what year your Volt is. All these data are pertinent to an evaluation of your efforts toward efficient driving.

some details:
-speed was about 60mph
-40psi
-I would say that the tires are at their mid life
-I'm a heavy user of cruise control (I use it whenever possible)
-outside temp about 60 degrees, climate setting was set to fan only
-odometer is at 22,222
-91 octane gas
-2013 chevy volt
glad to hear that the numbers are looking good!

 

[Elemental]

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[EvenSimpler]

My intuition is that this method would be particularly inefficient, given that the engine is typically less efficient when running for brief stretches. But I guess that'd depend on how long the engine is off between running and how much it and the cat converter cool off.

And given how good the results were, maybe I'm completely wrong. In fact, those numbers are almost unbelievably good. Did you charge mid-trip, or do some kind of hypermiling? 186 miles on one charge and only 2.2 gallons seems (almost) impossible, especially if you were using gas specifically on the inclines.

I noticed that the engine would rev up when switching to hold mode and would quite down after a minute or two. I'm not entirely sure why that was happening, but like you, my intuition told me that if the engine is making that much noise then it can't be a good thing for my mpg. this is why I posted this threat to ask knowledgeable volt owners if switching back and forth a good idea given as to how much noise the engine makes when switching to gas. and yes I did charge when I arrived to my destination, so I had a full charge on the drive back. and yes the engine was used on inclined roads.

I use hold to heat the car up. Once I have burned enough for warmth to come through I'll shut it off until it goes cold then start it again. This way, all the waste heat ends up in the cabin heater matrix and not in the front radiator where it is literally wasted.

thank you for this very useful information. at first your suggestion didn't make sense to me because I have zero knowledge of how the ac works in a car, but after viewing a video on youtube it makes perfect sense!