Don
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Re: Hypermiling the i-MiEV

Tue May 23, 2017 5:58 pm

I suspect most of us use these cars more in urban traffic than in places where we would want or need to use higher speed hypermiling skills. You can still get RR's of 80 or 85 miles in typical stop and go traffic if you accelerate very gently keeping the amps needle well below the mid mark *and* decelerate very gently only using the brakes after you're down to less than 10 to 15 mph. This does mean following an extra couple car lengths farther back than *most* drivers do, so you're not constantly making quick reactions to the changes in speed of the traffic in front of you

It still amazes me how many people drive with their brakelights flashing on and off several times per mile - Try not to be 'that guy'

After 'learning' to drive our EV's this way, I do pretty much the same in the gas powered cars too and the difference in MPG this makes is quite remarkable. I just keep thinking that 'Friction Braking Is Wasting Energy' and try as hard as I can to do as little of it as possible. I've gone more than 100,000 miles on the factory brake pads on a couple cars in the past already, but much of that can be attributed to downshifting manual transmission vehicles - Using constant 'B' mode and touching the brakes as little as possible was an easy thing to learn, given my long history of using minimal friction braking

We still get typical RR's in the mid 70's, in urban settings with an occasional 80 to 85 thrown in when we make trips that involve little to no speeds above 50

Don
2012 iMiEV SE Premium, White
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MalcolmReynolds
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Re: Hypermiling the i-MiEV

Wed Jun 07, 2017 11:10 am

I get the impression from some of the replies in this thread that possibly there is some confusion about how hypermiling fits their own use in the city or urban setting. Some of the techniques here are applicable to all driving environments and others are specific to less city oriented driving. For example the tire pressure thing is a no brainer. I have been driving my vehicles at the max sidewall pressure for many years now. You will notice less rolling resistance, better economy, and you will get a lot better tire wear. Simple, safe, easy to do.

For the city driver you still can employ some techniques. Don mentioned don't be "that guy" who is on the brakes, hammer down, on the brakes from light to light. Hypermiling is driver awareness. Watching the traffic, watching the lights, give yourself space, smooth on and off the go pedal. Back off and regen or coast whenever possible. Many times this works very well when watching the traffic lights and timing them. Any time you can avoid coming to a complete stop and conserve any momentum you are going to save energy.

Unlike others here who seem to be concerned about the permanent state of angry distracted and nut case drivers on the road I personally ignore them now. I am going to drive my drive, not worry about the fact that the others around me are insane. I am going to back off early and roll/regen to the light, I am going to easy on the go pedal. I am going to try to avoid coming to a complete stop any time it is possible. If that means backing off really early when I can see the light has changed ahead of me "then so be it" that is what I will do and I will let everyone go flying past me. I will be in the "slow lane" and will be trying to stay out of everyone's path.

I don't just look at this as saving energy, extending range, but largely also the significant reduction in wear and tear on my vehicle. This applies to a ICE, PHEV, or BEV equally.

Also look around for routes to your destination that may be more conducive to your driving. Watch for elevation changes and try to see if you can use them to your advantage. For example many of the local businesses that I frequent for my shopping if I go one way there is a more gradual incline going to the stores, it is a main road with lots of traffic and higher road speeds. However there is another "back way" that is a much steeper climb going to the businesses that is slightly longer way to get there. However I found that by watching the energy consumption even though it is longer I can use that route going back home from the stores and it is largely a coast/regen most of the way home. Plus it is a slower set of side streets with less traffic.

So analyze your possible routes and just think it through. This all works very well for your local driving conditions for locations and areas that you travel often since you know the streets, the traffic lights, and exactly where you are going and where you need to be in the lanes to position yourself for turns etc. It is when you get into less familiar territory that you have to just be situation ally aware and adapt. These techniques are for everyone, not just BEV drivers.

After a while it becomes second nature and I can't personally fathom driving like everyone else. Every time I stomp on the go pedal or twist my wrist on my motorcycle I am very aware of it. It just doesn't make sense, never has, but we all just seem to want to go with the flow. The "flow" is how we got into this mess to begin with. Once you get beyond that "peer pressure" to conform you will stop worrying about what everyone else thinks.

My advice is to just try to stay over in the "slow lane" and let the congo line keep going past. I tell them if they don't like my driving stay off the sidewalk! LOL Most of the time you will see them again at the next traffic light and still just as "angry" as ever. It is their permanent state, don't take it personally.

Hypermiling is not only fun, safe, can save you some money, but you will save your car a lot of abuse in the process. It all adds up to a win for you if you can add some of these techniques to your skill set.

FiddlerJohn
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Re: Hypermiling the i-MiEV

Tue Jun 19, 2018 1:05 pm

I measured regen efficiency several times uses two i-MiEV cars. When the front i-MiEV, going 30 mph, uses 8 BARS (~7 kWh) the towed i-MiEV using regen B adds 4 BARS (~3.5 kWh). This implies the i-MiEV is about 70% efficient from battery to wheel/road, and the round trip back to the battery is about 50%. So regen cuts range like braking, but only cuts half the range as braking.

Phximiev
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Re: Hypermiling the i-MiEV

Tue Jun 19, 2018 1:45 pm

FiddlerJohn wrote:I measured regen efficiency several times uses two i-MiEV cars. When the front i-MiEV, going 30 mph, uses 8 BARS (~7 kWh) the towed i-MiEV using regen B adds 4 BARS (~3.5 kWh). This implies the i-MiEV is about 70% efficient from battery to wheel/road, and the round trip back to the battery is about 50%. So regen cuts range like braking, but only cuts half the range as braking.


"B" versus "Eco"?
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bradleydavidgood777
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Re: Hypermiling the i-MiEV

Wed Jun 20, 2018 5:11 am

To me this indicates that you lose efficiency using B or Eco mode instead of using D, N and light brake (charging only brake) appropriately and planning far ahead so that you can avoid braking at all if possible which gives you a full 100% efficiency rather than losing 50% every time you let off the accelerator in B.
Last edited by bradleydavidgood777 on Tue Jul 31, 2018 4:10 pm, edited 1 time in total.
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Don
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Re: Hypermiling the i-MiEV

Wed Jun 20, 2018 7:38 am

'Loose efficiency?' - Better tighten that up!!

It all depends on the driver - You can 'coast' in B without shifting to N just by feathering the pedal so you're neither using power nor regenning. One pedal driving, no shifting required. The ammeter on the dash will tell you when you're in that sweet spot, but once you get used to driving this way, you can tell by the seat of your pants when you're neither using power or braking . . . . and when you need braking, just lift all the way off and you won't be swapping your foot from the go pedal to the brake

Don
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JoeS
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Re: Hypermiling the i-MiEV

Wed Jun 20, 2018 8:38 am

I personally find it impossible to keep my foot in that 'sweet spot' of zero power and zero regen, confirmed by using CaniOn.

There is no difference in the vehicle's energy consumption efficiency amongst D, ECO, and B. Any efficiency improvement comes from NOT using the brake, and in ECO the vehicle forcing you to drive efficiently by reducing the accelerator pedal input effect.

There is a more-nuanced portion to this discussion, which Aerowhatt and I have been debating for a year and which I am still trying to confirm. The premise is this: when in N the quiescent power draw of the car is less than when it is in any of the drive modes.

I love extremely-high regen (example: Bolt in L) and use B in both city driving and mountain driving; however, for the open highway downhill or coasting to that traffic light a block away I prefer zero regen and invariably pop the car into N.
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Don
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Re: Hypermiling the i-MiEV

Wed Jun 20, 2018 12:24 pm

JoeS wrote:I personally find it impossible to keep my foot in that 'sweet spot' of zero power and zero regen, confirmed by using CaniOn
Keep practicing Joe - It's not that hard . . . . you'll get there eventually. ;)

Note that the guy who did the 97 mile trip suggested using B mode was one reason he was able to make it so far, something most drivers don't seem capable of doing

https://www.youtube.com/watch?v=PWq304cPonM

. . . . . for the open highway downhill or coasting to that traffic light a block away I prefer zero regen and invariably pop the car into N.
Since the drive modes are electrically controlled, it shouldn't be that hard to put a switch on the gear shift knob to give you zero regen anytime you press it, no matter what drive mode you're in . . . . should it? That would be an addition we could all use. I love the max regen paddle in my Volt and I often wish I had a second one for no regen at all. Fiddling with the mechanical shifter to get me an electronic result seems so . . . . 20th century! :lol:

Don
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PV1
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Re: Hypermiling the i-MiEV

Wed Jun 27, 2018 11:12 am

Another complication with feathering the pedal at zero power is that the car moves the zero point dynamically with speed. If conditions allow, start down a hill at around 15 MPH, find zero power and hold the pedal steady. Watch the gauge move into Charge as your speed increases. The same happens, but adding motive power, as you lose speed.

I'd love to retrofit those paddles found in new JDM I-MiEVs into our current cars. I wonder how difficult it would be to add a switch to the wheel to put the car in neutral at any time, effectively adding a coast paddle.
:idea: :idea: :idea: :!: :!:

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Thanks.

Aerowhatt
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Re: Hypermiling the i-MiEV

Thu Jun 28, 2018 7:03 pm

Don wrote:'Loose efficiency?' - Better tighten that up!!

It all depends on the driver - You can 'coast' in B without shifting to N just by feathering the pedal so you're neither using power nor regenning. One pedal driving, no shifting required. The ammeter on the dash will tell you when you're in that sweet spot, but once you get used to driving this way, you can tell by the seat of your pants when you're neither using power or braking . . . . and when you need braking, just lift all the way off and you won't be swapping your foot from the go pedal to the brake

Don


The sweet spot doesn't matter because "coasting" in gear doesn't exist. When in gear the inverter is energized and supporting a rotating field in the motor which matches the rotational speed of the motor armature (which requires power to do). "Coasting" in gear is actually regening enough, to make enough power to create and support this field. It's easy to demonstrate to yourself with canion. A downslope on which you can steady state coast (in N) at 40 mph will yield an instantaneous miles/kWh in the range of 13 to 19 (in any drive gear while the amp needle is held at zero). That same stretch at 40mph in N will yield an instantaneous miles/kWh in the range of 130 to 190. It is ten times less efficient to "Coast" in a drive gear as you describe, than to actually coast in N. It's not in question, it is a demonstrable fact! Zeroing the needle in a drive gear is a very different thing than shifting into N. The second one is rightly called coasting. The first one is something else entirely.

Aerowhatt

P.S. The guy who did 97 miles recommending B as the most efficient mode for Hypermilin. He simply doesn't know any better. B mode is only most efficient for "jack rabbit driving" because it reduces friction braking in the driving style. Hypermiling is the antithesis of "jack rabbit driving" . . . so. He could do much better than he did using D and N. It's a a mathematical fact.
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