Techniques for improving range - Chevy Bolt EV Forum
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post #1 of 73 (permalink) Old 04-19-2019, 12:16 AM Thread Starter
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Techniques for improving range

I'm still figuring out the ins and outs of my Bolt, and one of the main things I'm trying to wrap my head around is the most efficient way of driving, while (mostly) keeping up with traffic, particularly on the highway.

So far the obvious things I've tried are:
-Keep speed down (no more than 65mph)
-Allow the car to slow on uphills and speed up on downhills, by basically keeping the power output constant
-Cruise control
-Accelerate gently

Still, I'm not really sure how much these are helping (other than not going over 65mph - going at 75mph seemed to very adversely effect energy consumption).

One thing I did notice almost immediately is that while in my old ICE vehicle, the difference in fuel consumption between going uphill and level terrain was generally ~2x (i.e. I got 30mpg on level vs. 15 mpg going uphill), the hills make a much bigger difference for the Bolt (e.g. 3x or more - 12kw vs. 35 kw). In theory some of that should be recaptured on the descent, but I haven't really seen that yet.

For reference, so far I've been getting about 3.5mi/kwh in highway driving, and 4.25mi/kwh city driving.

Any suggestions/thoughts? I'm particularly interested in what folks who take their cars on long trips have to say. Initially I wasn't really considering taking the Bolt on major trips, but it's proven to be a good traveling companion, and as time goes on, the notion of visiting the gas station has become more and more unappealing. Thanks!
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post #2 of 73 (permalink) Old 04-19-2019, 12:45 AM
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Inescapable facts:

1. Slower uses less energy. Decide how much more time you're willing to trade for less energy use.
2. If roadtripping and aiming to arrive in a minimum time, some have proven to their satisfaction it is faster to keep up the speed, then fast charge and drive fast again. The net time-to-distance is supposedly lower.
3. Forget every ICE lesson you've learned. The GM engineers have done all the work for you. Pick a time/distance tradeoff, set your cruise and let the system do the work. There's literally no way to game the Bolt as the hypermilers used to do with ICEs. That was then. This is now.

jack vines
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post #3 of 73 (permalink) Old 04-19-2019, 02:25 AM
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Slow acceleration and slowing uphill isn't going to save you much, except that driving slower in general is the #1 technique to increase range. Everything else is a footnote.

ICE vehicles are more efficient going uphill (despite the reduced MPG), and generally get better MPG in hilly terrain, unless brakes are used on the downhill portion.

Electric motors don't vary much in efficiency throughout the power range, unlike ICE engines, which are atrocious at low power, and just very bad at higher power.

Increasing tire pressure is a known technique to increase efficiency.
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post #4 of 73 (permalink) Old 04-19-2019, 02:28 AM
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I also find that going with the flow of traffic, and especially travelling a safe but close distance from a large vehicle gains me a significant amount of mileage. (As in 2 to 3 seconds behind, as per the display.)

I'm also very familiar with the timing of lights along my route, and make every effort to coast up towards the red so that it turns green just as I'm arriving.

Gentle acceleration helps too. Obviously this is less fun than stomping on the accelerator.
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post #5 of 73 (permalink) Old 04-19-2019, 03:05 AM
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Reducing speed is going to help the most. Properly inflated or overinflating tires will help as will not running the HVAC at all.

OP should look at https://www.tesla.com/blog/model-s-efficiency-and-range and https://web.archive.org/web/20100721...ncy-and-range/. Yes, it's Tesla but the principles are the same. Notice the optimum speed for range for the S?

Has anyone put together a range chart sort of like http://www.mynissanleaf.com/viewtopic.php?t=4295 but for Bolts? It doesn't need to be as elaborate with all the battery bars and all. Anyway, it asserts on a 24 kWh Leaf w/new battery w/all the conditions listed there that a gen 1 Leaf going 35 mph, should achieve 6.3 miles/kWh and be able to go 132 miles until dead. At 75 mph? 3.0 miles/kWh -> 62 miles until dead. There's more to the chart but I don't have the time to explain the rest right now. A new 24 kWh Leaf has about 21 to 22 kWh usable capacity.

Tony Williams asserts the optimum speed for range on a Leaf is 12 mph. I wouldn't be surprised if on Bolt it's somewhere between 10 and 25 mph.

Edmunds on the 73 mile EPA rated '11 Leaf when it was pretty new did exactly 132.0 miles at 35 mph: https://www.edmunds.com/nissan/leaf/...itter-end.html. This was probably Tony's starting point.

The record holder of http://www.mynissanleaf.com/viewtopic.php?t=7022 did 188 miles on a 24 kWh Leaf. He was probably going a lot slower than 35 mph.
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post #6 of 73 (permalink) Old 04-19-2019, 04:14 AM
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Quote:
Originally Posted by dhazeghi View Post
I'm still figuring out the ins and outs of my Bolt, and one of the main things I'm trying to wrap my head around is the most efficient way of driving, while (mostly) keeping up with traffic, particularly on the highway.

So far the obvious things I've tried are:
-Keep speed down (no more than 65mph)
-Allow the car to slow on uphills and speed up on downhills, by basically keeping the power output constant
-Cruise control
-Accelerate gently

Still, I'm not really sure how much these are helping (other than not going over 65mph - going at 75mph seemed to very adversely effect energy consumption).
Other than driving slow, they're not helping.

You don't need to slow going up hills. Speeding up going down hills might save energy if speeding up didn't also add air resistance. Moderatly aggressive acceleration is fine, too.

On the freeway, go with the flow, drive behind another vehicle at whatever speed. Big SUV or truck will work well. You can still be at a reasonable following distance. Driving 70 mph behind someone is probably better than driving 65 mph with everyone passing you.

For modest-sized trips that aren't pushing the limits of the battery, best to just drive however the mood suits you and enjoy the car.

If you need to stop and charge, mostly you can drive as fast as you like. Driving faster uses more power, but it's still a win after factoring in added charging time (assuming a decent-speed DCFC station).
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post #7 of 73 (permalink) Old 04-19-2019, 08:37 AM
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for around town, I stay off the highway. have been averaging 5.0m/kWh. but that was through the winter. living in the southwest, I can live without heat, but can't live without air conditioning. so my summer range average drops.
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post #8 of 73 (permalink) Old 04-19-2019, 10:11 AM
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By far, I've found the environmental system of the Bolt has the most impact on mileage. I generally drive with the system set to "automatic", which means it's running behind the scenes to keep me comfortable. But, during the Spring, when temps are moderate, I turn it off completely and notice a nice jump in energy efficiency.
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post #9 of 73 (permalink) Old 04-19-2019, 11:49 AM
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As an owner and user of a sub-100 mile EV, a Fiat 500e, where inefficiency can literally leave you stuck on the side of the road, I mostly concur with the assessment below.

Quote:
Originally Posted by Vertiformed View Post
Other than driving slow, they're not helping.

You don't need to slow going up hills. Speeding up going down hills might save energy if speeding up didn't also add air resistance. Moderatly aggressive acceleration is fine, too.
Efficiency isn't always measured in mi/kwh. We're already winning because every EV is tons more efficient than an equivalent gasmobile. It's why the Bolt can get over 220 miles of range with a battery that is the equivalent of less than 2 gallons of gas. So modulating hills really isn't going to significantly change that. As others have pointed out, the #2 source of consumption after speed is climate controls, especially resistance heating. AC isn't awful, but it does cut into the power budget a bit.

Quote:
On the freeway, go with the flow, drive behind another vehicle at whatever speed. Big SUV or truck will work well. You can still be at a reasonable following distance. Driving 70 mph behind someone is probably better than driving 65 mph with everyone passing you.
This is the only point I have a disagreement with. When I know I'm going somewhere that's going to require a recharge while out, I set the cruise on the highway to 60 MPH and drive in the far right lane regardless of traffic flow. 65,70,75 MPH or higher cuts into the power budget by a significant margin. Personally I find that using big trucks as a buffer by riding in front of them offers the most protection from the zoom zoomers.

The following point is the most crucial one.
Quote:
For modest-sized trips that aren't pushing the limits of the battery, best to just drive however the mood suits you and enjoy the car.
Driving normally is the best revenge. Unless I know I'm going a route where efficiency is crucial, I never worry about it. I know in non-winter seasons that my full commute is less than 50% of the battery driving normally. With that much to spare, it's not worth bothering trying to modulate efficiency. Like I said, we're all already winning.

Quote:
If you need to stop and charge, mostly you can drive as fast as you like. Driving faster uses more power, but it's still a win after factoring in added charging time (assuming a decent-speed DCFC station).
In my situation with L2 only, I actually have to use destination timeframes to make that decision. If I'm parking at a charging station for a couple of hours or more, I don't worry about it. However, if time is a factor, typically I'll slow down driving to the destination to conserve electrons as the further I dip down the SOC curve, the longer I have to sit at the charging station to recoup the energy to get back. But honestly, if I had a DCFC capable EV, and knew that there was a decent speed DCFC station along the route, it would be a worry free situation as far as I was concerned.

ga2500ev

Last edited by ga2500ev; 04-19-2019 at 11:51 AM.
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post #10 of 73 (permalink) Old 04-19-2019, 11:54 AM
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Run the tires at 40 psi cold. Turn off the HVAC. Run outside air on the windshield. Use seat and wheel heat. Set the cruise control to the speed limit, or 2-3 over. Don't touch the brakes, except when stopped...regen only. Forget coasting, pulse and glide, etc. Accelerate/decelerate like they taught you in drivers ed....don't be a d_ck.
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