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She is the lady that took the pictures of the car at the top of Mt Washington and posted them on their facebook page.
Oh... an 80 kg photographer! Ha. Ok, that makes more sense. :)

Volt can do 4-6 miles per kWh
Idk about that. Even if you're only measuring power drawn from the battery (excluding charging losses), 6 miles/kwh (167 wh/mi) is still very difficult to achieve. That would equate to a 60+ mile EV range on a 2011/2012 Volt, and even higher on a late-2012/2013 model. Almost no one gets that much.

If you're measuring from the outlet and you count charging losses, I think 4.5 miles/kwh is about the best you can *reasonably* achieve. And even that takes some deliberate hypermiling techniques.
 

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So, Jedi, if Li batteries are that good (sorry...) then why does it take 13.3 kwh to charge back 10kwh? Surely you're not saying the built in charger is only 70% efficient! As an EE, I know better than that one, and as a lifelong fooler-arounder-with-batteries-all-kinds, I haveta call bull on the 95 percent round trip efficiency on ANY battery. It just ain't so, Joe. Sure, Li's better than lead acid, no argument, but not that close to perfect by a long shot.
The 13.3 kWh sounds like the energy required in a L1 charge as you are charging the vehicle over a longer amount of time compared to L2. I typically see ~13.5 kWh for L1, and ~12.6 kWh for L2 charging. That difference in energy is probably due to losses in the power electronics to convert AC-DC, the transformer, and charging the auxiliary battery. The transformer is probably less efficient at 120v, than at 240v, plus the extra 6 hours required to charge at L1, means that there will be more operating losses on the basis that those electronics have a base load that operates longer.

I recalled you mention having a lead acid battery system for your PV array, so I'm betting your experience with low battery charge efficiencies, is due to the poor efficiency in those systems. Typical lead-acid batteries have a full charge/discharge energy efficiency of around 85%, so if you had replaced the Volt's Lithium pack with a lead acid pack, you'd see an even lower efficiency. (Its also important to note that lead-acid batteries have different charging efficiencies depending on SOC so if you're mostly charging the battery close to full from a PV system you'll see even worse efficiencies - http://photovoltaics.sandia.gov/docs/PDF/batpapsteve.pdf)

Based on the data above, a typical Volt discharge is ~10.4 kWh DC and requires about 12.6 kWh AC to charge = 82.5% AC-DC Charge Efficiency
With a lead acid pack you'd would probably see something closer to 14.8 kWh (10.4 kWh / (0.825 * 0.85)) required to charge on L2.

I don't usually like bringing out credentials, but as an as well EE who works daily on Li-ion battery systems, I have a lot of experience with real world data that brought about my conclusions. Of course, I always welcome differing knowledge that would explain otherwise especially as my experience in this field is still only a few years.
 

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About the energy conversions:
In the Focus, there is only one permanent magnet electrical motor, that turns to a generator when the car goes into regen mode.
As it's the same motor to put the car in movement, would it's efficiency to convert electrical energy to movement would be the same
as to convert movement to electrical energy?
Small but important point, you're not converting movement to electrical energy you're converting it to chemical energy. So the energy of the wheels turning have to be transmitted to the generator, which has to convert the movement to electrical energy, after which the electrical energy has to be converted to chemical energy. To follow up on your point, the drive train from battery to wheels isn't 95% efficient. Not even close. So how could the efficiency going the other way, which really should be less efficient, be more efficient?

Let's again go back and consider charging. An AC-DC converter should be 98% efficient. At that point you have electricity which will charge the battery. To get to this point with regen, you have to have motion at the wheels get to the generator, which has to produce DC electricity. How likely is it that the wheels--> generator--> electrical energy conversions will be 98% efficient?
 

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Discussion Starter · #24 ·
Small but important point, you're not converting movement to electrical energy you're converting it to chemical energy. So the energy of the wheels turning have to be transmitted to the generator, which has to convert the movement to electrical energy, after which the electrical energy has to be converted to chemical energy. To follow up on your point, the drive train from battery to wheels isn't 95% efficient. Not even close. So how could the efficiency going the other way, which really should be less efficient, be more efficient?

Let's again go back and consider charging. An AC-DC converter should be 98% efficient. At that point you have electricity which will charge the battery. To get to this point with regen, you have to have motion at the wheels get to the generator, which has to produce DC electricity. How likely is it that the wheels--> generator--> electrical energy conversions will be 98% efficient?
I would be interested to find the numbers for the Volt and the Focus on the efficiency of transferring energy from the battery to wheels. Would you have those datas for the Volt? Or, any relevent data about this?

I also agree that it seems unlikely to reach the 95% regen efficiency. This is the whole point of the original posting. However, the darn experimental numbers point to a very high regen efficiency. Somewhere in an interval between 78% to 96%
So, did Ford engineers used some sort of ultracapacitors to help the battery reach a higher efficiency ratio or is it another way they implemented the regen circuitry, I truly don't know, but I am nevertheless quite impressed by the overall drive system of the FFE.

Francois
B2653
 

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Great data.
9.3kWh up
9.3-4.1=5.2kWh generated down is 56% net regen
Dispensing with metric the round trip was roughly 3.75 miles per kWH

I average 5.0 miles per kWh with my Volt conclusvely proving the Volt is 5/3.75 or 1.33 better than an FFE.
Mine of course is exceptional because I use TVA Hydro electrons versus whatever crap The FFE used.
 

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Discussion Starter · #26 · (Edited)
jfkirk, you are overlooking the energy required to move to car on 24.8km.
Your math holds only if there is zero energy required to drive that 24.8 km distance, which is impossible, we would have a
perpetual motion machine! ;-)

The basis I used for energy used to do the "horizontal" travel was 0,150kWh per km.
The "vertical" travel of 1402m required 7.2kWh.

But your math give one interesting boundary: the worst case regen boundary: the regen efficiency is higher than 56%.

Francois
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Great data.
I average 5.0 miles per kWh with my Volt conclusvely proving the Volt is 5/3.75 or 1.33 better than an FFE.
Mine of course is exceptional because I use TVA Hydro electrons versus whatever crap The FFE used.
Keep in mind that your driving style and route gives you ~200 Wh/mi (my preferred metric) rather than miles/kWh. You can convert that to MPGe by dividing that value by the energy content in a gallon of gas which is typically 33,705 Wh. So your driving style would indicate a fuel efficiency 168.5 MPGe, much better than the 2012 Volt rated value of 95 MPGe.

If your driving habits, can correspond directly linear to that of the FFE's efficiency, you would get around 186.23 MPGe (~10% more efficient).

Of course that still pales to my all time record of 195 MPGe over 30 miles =D (~800 ft elevation change).
 

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Your instrument panel integrates all factors. Rolling resistance, aerodynamic losses...everything that you are trying to include a second time.

Not all Volts have kWh reported. Its a nice piece of data.
 

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I would be interested to find the numbers for the Volt and the Focus on the efficiency of transferring energy from the battery to wheels. Would you have those datas for the Volt? Or, any relevent data about this?
80% or 85% is sticking in my mind but I may be making this up. It should be about right. The battery should be 98% efficient. The motor maybe 92%. That leaves the rest of the drive train. Give this 92% and you end up with 83%.
 

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80% or 85% is sticking in my mind but I may be making this up. It should be about right. The battery should be 98% efficient. The motor maybe 92%. That leaves the rest of the drive train. Give this 92% and you end up with 83%.
I remember seeing the efficiency stats for the Volt's electric motor, and it varies a lot. It's only over 90% efficiency for a small area of its load/speed. The average efficiency would probably be in the high 80% range, but I don't recall seeing that exact number. That chart might have been overall efficiency (battery to wheel), but I doubt it, since the chart mentioned motor efficiency. Also, over 90% from battery to wheel under any circumstances would be quite dubious.
 
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