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the energy required to reach a given velocity is the same under slow acceleration (low power) or fast acceleration (high power).
You guys are way off base. The faster the acceleration, the more energy is used to reach the same speed. This applies to any motive force. No "free" ride here. Once you have gained a certain speed, it is true the potential energy from your momentum is now the same.
 

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You guys are way off base. The faster the acceleration, the more energy is used to reach the same speed. This applies to any motive force. No "free" ride here. Once you have gained a certain speed, it is true the potential energy from your momentum is now the same.
Simply not true.

The energy (called kinetic) of a moving body is 1/2mv^2 (FYI momentum is mv. not the same as energy). It doesn't matter how quickly you accelerate the car. The energy required is the same. m and v only. There is no acceleration "a" term in the equation.

If you want to accelerate quickly then you do need more power (kw or HP). If your source of power is efficient over a wide power band then you will be just as efficient accelerating quickly as accelerating slowly.

energy = power X time. (v=a X t ). Kw is power. Kwhrs is energy. 10 kw X 20sec = 20 kw X 10sec. Yes, twice the acceleration requires twice the power but it is only applied for half the time to reach the same velocity.

A motor/battery combo is quite efficient over a wide power band unlike an ICE which needs a lot of gears to stay in its most efficient power zone. This is one reason why hev/phev/EV are more efficient than ice cars in city driving. (Regen braking is the other big reason.)
 

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"It doesn't matter how quickly you accelerate the car. The energy required is the same."

I would concur with that, solely from my observations of the SoC display in the car. I have two options to reach the top of the hill I live on. Both routes are the same distance, but one goes to the right, is steeper with a stop sign about half way up, then more climbing. The other way goes to the left, winding around but with a less inclined road. They both reach a stop light at the top. I can take the steeper route, which requires harder acceleration, and the SoC shows 95% at the top (leaving the garage indicating 100%). I can take the shallower route, and really baby the throttle, and I still show 95% at the stoplight. So, traveling the same distance, with two different driving patterns, but the same amount of power used either way.
 

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"It doesn't matter how quickly you accelerate the car. The energy required is the same."

I would concur with that, solely from my observations of the SoC display in the car. I have two options to reach the top of the hill I live on. Both routes are the same distance, but one goes to the right, is steeper with a stop sign about half way up, then more climbing. The other way goes to the left, winding around but with a less inclined road. They both reach a stop light at the top. I can take the steeper route, which requires harder acceleration, and the SoC shows 95% at the top (leaving the garage indicating 100%). I can take the shallower route, and really baby the throttle, and I still show 95% at the stoplight. So, traveling the same distance, with two different driving patterns, but the same amount of power used either way.
actually your consuming energy climbing a hill in addition to what ever energy is used to accelerate the car.

Still the principle is the same. The potential energy stored up climbing the hill is the same whether you climb via a steep road or or a gentle road.
 

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Ok, before we all are going to “kill each other” on how well we remembered the stuff we had to learn during physics class, let us go back to a practical example to figure out why you should use EV mode in the city and ICE on the highway. That is if you have the PHEV.

As someone rightfully stated the power an ICE can produce is not constant over the total range of RPM available to propel the car. This has been THE engineering challenge forever since ICE were used in vehicles. To optimize the solution engineers worked forever on designing transmissions and the fuel burning process. Electromotors have the ability to pretty much use the maximum power over the complete RPM range. That is why there is no need for a transmission in an EV.
Engineers have studied and experimented at length what will create overal average the best fuel consumption for a car without sacrificing too much performance. The result remains a sub-optimal energy consumption.

I can’t say my driving is typical, but I have driven 2 cars that are about the same size and shape (Niro EV and the BMW X1 2L Turbo) both having motors with roughly same power (150kW) and I drove them under the same circumstances (driving style, terrain). The long term average on my EV is 16.1 kWh/100km, my X1 consumed on average 12l/100km. I know it is metric, but for comparison this makes it a bit easier. So how much energy is in 12l of gasoline? According to this answer by a Professor 12l gasoline contains 108 kWh of energy! If I would assume that the BMW engine is highly inefficient (BMW would disagree!) at 20%, then there is almost 22kWh used per 100km to obtain the same driving. Which shows the inefficiency of the transmission, but also the lack of the ICE being able to regenerate forces to slow down the car back into the energy form it has on board (gasoline).

So long story short for the PHEV drivers: use EV mode in the city and ICE on a longer highway stretch as soon as you arrive at cruising speed.

Is the car able to detect this and automate this for you? So you don’t need any of the knowledge while driving and can listen to the music? Only when it has a location based system with data on the type of road you are on in combination with real-time traffic conditions, so it can reliable predict the driving style (e.g. GPS based navigation system you can find in the Niro). The computer making the decisions which engine to use will need this info in combinatinon with speed and the throttle position. Since a nav system in a car is still being sold as a way to find your way and still seen as a luxury for which you can charge additional money, it is not yet used for this purpose. Maybe some day it will become a competitive advantage for a car manufacturer to automate the optimal use of motors in a PHEV. I am sure the engineers have this already worked out, but the product managers and marketeers are not yet in. Time will tell!
 

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"It doesn't matter how quickly you accelerate the car. The energy required is the same."
[…]
So, traveling the same distance, with two different driving patterns, but the same amount of power used either way.
Your last sentence should read “energy” instead of “power”. Many folks mix these terms up, however they are not the same.
Unless these 2 routes you take exactly the same time to travel, the total of power used will be different. But that doesn’t matter, because the variable is energy and the State of Charge is a relative measurement of the total energy capacity of the battery. The power only matter for the level of acceleration and to obtain speeds.

Eg. the EV battery holds 64kWh energy, but can produce up to 170kW of electrical power. In theory if I would drive with full power the battery would be empty in 22 minutes. The car is limited at about 107 mph to prevent the motor from rotating into speeds where it could get damaged. I did this once and I recall the display showing 150kW of electric power being applied. So at max speed the battery would run out of energy in 45 miles! Hence the eco mode, which will reduce the max speed you can drive in order to force you getting better range.
 

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Your last sentence should read “energy” instead of “power”. Many folks mix these terms up, however they are not the same.
Unless these 2 routes you take exactly the same time to travel, the total of power used will be different. But that doesn’t matter, because the variable is energy and the State of Charge is a relative measurement of the total energy capacity of the battery. The power only matter for the level of acceleration and to obtain speeds.

Eg. the EV battery holds 64kWh energy, but can produce up to 170kW of electrical power. In theory if I would drive with full power the battery would be empty in 22 minutes. The car is limited at about 107 mph to prevent the motor from rotating into speeds where it could get damaged. I did this once and I recall the display showing 150kW of electric power being applied. So at max speed the battery would run out of energy in 45 miles! Hence the eco mode, which will reduce the max speed you can drive in order to force you getting better range.
Interesting. 150kW to do 107 mph? Are you sure? My phev uses ~15kW to do 80 mph. Considering wind drag effect alone (107/80)^2 = 1.8 I would have expected 15 x 1.8 = 27kW to do 107 mph

Please check again how many kW for your ev to do 40, 80, 100 mph.
 

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Interesting. 150kW to do 107 mph? Are you sure? My phev uses ~15kW to do 80 mph. Considering wind drag effect alone (107/80)^2 = 1.8 I would have expected 15 x 1.8 = 27kW to do 107 mph

Please check again how many kW for your ev to do 40, 80, 100 mph.
I believe the formula is bit more complicated to calculate the power as a function of speed taking drag into account. And as far I remember with drag in the equation the power is function of speed^3. I also think your relative increase calculation is the wrong way of calculating.

Now that I have a car scanner which can record all these variables from the car’s ECU, so I could definitely record a test. But keep in mind we have a speed limit of 60mph where I live... so I will need an almost empty straight highway, which is not around the corner and make sure law enforcement is not watching.
To be honest the 150kW I saw briefly (as I kept my eyes on the road) was likely while I was still accelerating. The test was more to see how the motor would keep pulling until it reaches its limit. Yes, it does keep pulling.

In the screenshots you can see the actual power used to accelerate to and maintain speed. Now keep in mind that I use adaptive cruise control in eco mode which leverages regen as good as possible and speeds up (when possible) with a modest acceleration. Speeds are in km/h. Just devide by 1.6 to get in mph. Power is in kW.
 

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I believe the formula is bit more complicated to calculate the power as a function of speed taking drag into account. And as far I remember with drag in the equation the power is function of speed^3. I also think your relative increase calculation is the wrong way of calculating.

Now that I have a car scanner which can record all these variables from the car’s ECU, so I could definitely record a test. But keep in mind we have a speed limit of 60mph where I live... so I will need an almost empty straight highway, which is not around the corner and make sure law enforcement is not watching.
To be honest the 150kW I saw briefly (as I kept my eyes on the road) was likely while I was still accelerating. The test was more to see how the motor would keep pulling until it reaches its limit. Yes, it does keep pulling.

In the screenshots you can see the actual power used to accelerate to and maintain speed. Now keep in mind that I use adaptive cruise control in eco mode which leverages regen as good as possible and speeds up (when possible) with a modest acceleration. Speeds are in km/h. Just devide by 1.6 to get in mph. Power is in kW.
thanks Peter, excellent data

Yes, wind resistance is proportional to v^3 but it's influence on mpg is proportional v^2. Similarly drive train friction is generally proportional to v but for MPG calculation its 1.

Yes, there must be some acceleration power included in your 150KW reading.

Your 100 kph (60mph) results show 10-20kW which is considerably higher than my experience. What kind of terrain for this run?

Good stuff.
 

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Your 100 kph (60mph) results show 10-20kW which is considerably higher than my experience. What kind of terrain for this run?

Good stuff.
Note this power in kW, not energy. Secondly, I have the EV, not the PHEV, completely different ball game, When I drive 100 kmh my energy use is about 15-16 kWh. The terrain is not flat by the way. We hardly have any flat roads here in Metro Vancouver.
 

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Note this power in kW, not energy. Secondly, I have the EV, not the PHEV, completely different ball game, When I drive 100 kmh my energy use is about 15-16 kWh. The terrain is not flat by the way. We hardly have any flat roads here in Metro Vancouver.
Typo, and past the edit time.
At 100 kmh my energy use is 15-16 kWh/100 km based on observations of the car display. With a constant speed of 100 kmh this means 15-16 kW power is applied, right?

BTW, what amount of power does your PHEV uses at 60 mph? Is there an indicator on the car display or do read from the ECU?
 

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Typo, and past the edit time.
At 100 kmh my energy use is 15-16 kWh/100 km based on observations of the car display. With a constant speed of 100 kmh this means 15-16 kW power is applied, right?

BTW, what amount of power does your PHEV uses at 60 mph? Is there an indicator on the car display or do read from the ECU?
Yes. Kw is power. Kwhr is energy.

My phev is ~15kw for ~70mph over ~2min average from car dash display. So it's about the same just like we should expect.

Are your graphs from car display or ECU?
 

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Are your graphs from car display or ECU?
ECU. Which BTW is the same source for the car display. But the Car Scanner app allows to record the data in time series and has a built in feature to graph the time series (per screen shot). The car system itself won't allow you to get these graphs. Car scanner can also export the time series as CSV so you can do more advanced post-processing to your likes. Haven't done that yet.

When I have more time I am going to approach the developer with some advice on how to include consumption metrics for the EV. Right now he still only has mpg and l/100km for the traditional fuels: gasoline, diesel, ethanol, methanol, propane, methan, flex fuel. :eek:

So if any of you have any suggestion, I can take those into account. And then you all go get the app and we can share our experiences. (The app is free with ads, a paid version will remove ads). You will need to buy a reliable OBD2 adapter. The developer has some good recommendations on his site.
 

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This weekend I reset the accumulated info counters to see what pure city driving does in my neck of the woods: I averaged 14.5 kWh/100km (4.3 miles/kWh). That was in ECO mode but driving as swift as usual. So clearly my long time average of 16.1 kWh/100km is mainly because of 75% highway driving at 60 mph and more.
 

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Just got my monthly UVO health report stating I drove 1985 km and had 833 kWh of regen.
If I a use my long term average of 16.1 kWh/100km I have net consumed 320 kWh. Which means the total energy needed to accelerate the car and maintain speed was 1152 kWh. Curious what other EV owners see in their consumption. Seems to me like I am getting relatively a lot energy back from regen. But on the other hand I love the acceleration 0:), we have hilly terrain and I always have regen set to max (which the Smart Cruise Control also leverages).
 

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ECU. Which BTW is the same source for the car display. But the Car Scanner app allows to record the data in time series and has a built in feature to graph the time series (per screen shot). The car system itself won't allow you to get these graphs. Car scanner can also export the time series as CSV so you can do more advanced post-processing to your likes. Haven't done that yet.

When I have more time I am going to approach the developer with some advice on how to include consumption metrics for the EV. Right now he still only has mpg and l/100km for the traditional fuels: gasoline, diesel, ethanol, methanol, propane, methan, flex fuel. :eek:

So if any of you have any suggestion, I can take those into account. And then you all go get the app and we can share our experiences. (The app is free with ads, a paid version will remove ads). You will need to buy a reliable OBD2 adapter. The developer has some good recommendations on his site.
I now have Car Scanner .

It's the only app i've found that includes Niro PHEV motor /battery stats.

Motor rpm, battery voltage and current, individual cell (96) voltage. ......

Confirmed, a.c. 400 to 1200+ watts, max motor watts ~45000.

Just getting started.
 

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@charlesH, it would be great if you can get some hard numbers about if the traction motor is drawing any power while stopped with the foot on brake. It certainly feels like the "creep" is energizing the motor even while stopped. I'd like some current data on how much, if any, is being consumed. I'm not questioning the person who reported it earlier, but in case there's been firmware updates I'd like to know what you might measure. Need to determine if it's enough of a draw to justify moving to neutral while stopped, then remembering to move back to Drive when it's time to go. I've forgotten that a couple of times, and it's embarrassing to be sitting there pressing the pedal and nothing happens. :eek:
 

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[MENTION=7791]Need to determine if it's enough of a draw to justify moving to neutral while stopped, then remembering to move back to Drive when it's time to go. I've forgotten that a couple of times, and it's embarrassing to be sitting there pressing the pedal and nothing happens. :eek:
It becomes something you do without even thinking. While I came from manual cars that I always shifted into neutral at stop lights to relax my left leg, I went the first eight months without doing that on the Niro until this issue came up in the forums. I think in the last 10 months, I've only forgotten to shift back twice. Really strange as you cannot rev the engine in neutral so you have to think about why you are not moving. Resting your right hand on the shifter is a good way to remember you have to shift!

Kind of cool to be sitting at lights without your brake light on (can only be done on dead flat surfaces - doesn't take much for the car to roll). Cars behind you must think you are driving a manual. In my case, I found the eco emblem on the back to be ugly so I removed it. They would really wonder if they knew I was driving a hybrid. There is a manual shift hybrid by the way, the Honda CRZ. Mpg not so good on that car, maybe not as good as a Yaris. As a former CRX owner (HF high mpg version), I would have have loved an even higher mpg CRX hybrid, but the CRZ is not it.
 

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@charlesH, it would be great if you can get some hard numbers about if the traction motor is drawing any power while stopped with the foot on brake. It certainly feels like the "creep" is energizing the motor even while stopped. I'd like some current data on how much, if any, is being consumed. I'm not questioning the person who reported it earlier, but in case there's been firmware updates I'd like to know what you might measure. Need to determine if it's enough of a draw to justify moving to neutral while stopped, then remembering to move back to Drive when it's time to go. I've forgotten that a couple of times, and it's embarrassing to be sitting there pressing the pedal and nothing happens. :eek:
level parking lot

P w/wo brake ~0.6a X ~400V = ~240W
N w/wo brake ~0.6a X ~400V = ~240W
D w brake ~0.6a X ~400V = ~240W
D wo brake ~3.0a xv~400V = ~1200W (creep mode)

Just put the brake on when in D and you won't draw any "creep" power.
 
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