EPA: Nissan Leaf gets 99 mpg equivalent

[Frank]

The Leaf has 24 kwh or usable energy, it would never go 100 miles on 19kwh and Nissan would never cycle the pack to 0 if the total were only 24 kwh. I'm betting it's near 30 or and actual 30 kwh, I'm sticking to that prediction. I'm also betting the Leaf pack voltage of 400V is boosted like the Prius and IS NOT the actual pack voltage. After careful inspection of the contactors and packaging they are far too close and not designed for 400V. This makes complete sense for a 10K rpm motor and to eliminate sag and increase efficiency. And the Leaf charger is not that inefficient and contrary to what the misinformed Nissan people say it is behind the back seat not behind the inverter, that's a voltage booster likely. In fact the Leaf parts look identical to the Prius Denso parts and connectors in the Pack. Now I'm way off topic.

I'm trying to understand the Nissan recommendation to extend battery life by routinely charging the pack up to 80% rather than a higher percentage (e.g. full 100% charge). IF the actual pack size is 30kwh, then when you program the charging timer to charge to 80%, is that 80% of 30kwh or 80% of 24kwh?

 

[EVDRIVER]

The Leaf has 24 kwh or usable energy, it would never go 100 miles on 19kwh and Nissan would never cycle the pack to 0 if the total were only 24 kwh. I'm betting it's near 30 or and actual 30 kwh, I'm sticking to that prediction. I'm also betting the Leaf pack voltage of 400V is boosted like the Prius and IS NOT the actual pack voltage. After careful inspection of the contactors and packaging they are far too close and not designed for 400V. This makes complete sense for a 10K rpm motor and to eliminate sag and increase efficiency. And the Leaf charger is not that inefficient and contrary to what the misinformed Nissan people say it is behind the back seat not behind the inverter, that's a voltage booster likely. In fact the Leaf parts look identical to the Prius Denso parts and connectors in the Pack. Now I'm way off topic.

Agree about the >24kWh capacity. At a recent DriveTour, a Leaf engineering type (not one of the "Disney ride operators") said he couldn't divulge the total pack capacity to me but put it above 28 less than 30. Interesting about the pack boost. Wouldn't that interfere with the 400VDC QC scheme? Or do you suppose it's a reason why QC has to be done at the factory; cables run the length of the vehicle and pack boost has special electronics?

I'm putting the pack between 29.5-30 kwh. As far as the boost converter like the Prius, this has nothing to do with L3 charging which is over 400V AC in and supplies DC out to the pack but up to 500V DC. The pack components may not be production so I am not 100% certain on exact the pack voltage but 400 seems high, as far as the pack size I'm very confident it is close to 30 kwh. Remember, the L3 needs to be universal to charge many EVs and supplies the voltage requested. Even with a nominal pack voltage of 400 a boost converter still adds efficiency and allows for smaller inverter transistors and smaller motor windings and faster switching, the boost converter also prevents voltage sag on a lower pack keeping speed linear. These are educated guesses at this point but I'm solid on the pack capacity though.

If one were to hypothetically turn the car on and use an AC meter set to 600V and apply it to the two main contacts on the L3 port the actual pack voltage could possibly be found. Assuming a certain architecture and no second pack contactor. The car may not go "ready" if the charge port is open though

 

[hill]

How does the EPA come up with 73 miles for "range"?
Do they have a specific test?
Or, perhaps just ask GM for a number?

Simple!
They calc how much fuel (btu's) to make electricity. Their formula is defective because if fails to factor in the TON of electricity ... just to MAKE/REFINE fossil fuel ... whether it's coal, oil, gasoline, or natural gas. Then, if you have to factor in running the (trillion dollar) MILITARY all over the world, to keep the toxic explosive fuel running ... just so we can keep the trillion dollar military machine running all over the world ... well ... we don't want to go down that road now, do we. ... oh, did I mention our Leaf will be charged via our PV panels?

 

[MikeD]

If EPA's Leaf range = 73 miles results in EPA's Leaf MPGe = 99, then if you assume FTC's Leaf range = 96 miles thru 110 miles, I infer FTC's Leaf MPGe = 130 [= 99*(96/73)] thru 149 [= 99*(110/73)].

Your mileage may vary...

 

[DaveinOlyWA]

Kinda curious as to how GM could announce the volt getting 230 mpg but the Leaf only gets 73... but then again. The volt announcement was updated wasn't it?

 

[tbleakne]

In my opinion EPA is making a big mistake basing their calculations on 33.7kWh equivalent in a gallon of gasoline. This value sounds too high. I need to check this more, but I believe this value may be equal to the raw chemical energy of a gallon of gasoline. If so, it does not take into account the overall efficiency that an ICE car attains converting chemical energy into motion. I believe this efficiency is typically considerably less than 50%. An electric drive train is much more efficient, perhaps 80% efficient converting electrical energy into motion.

Another way to look at it is that the EPA is saying the Leaf's energy storage with a fully-charged battery is equivalent to only about 3/4 of a galleon of gasoline (24Kwh usable, with hidden spare capacity to prolong battery life). A Leaf is not that much heavier than a Prius, so the amount of actual mechanical energy expended in going 100 miles on level terrain should be comparable. A Prius probably has one of the most efficient ICE drivetrains available, but it uses more than 2 gallons to go 100 miles.

 

[lne937s]

How does the EPA come up with 73 miles for "range"?
Do they have a specific test?
Or, perhaps just ask GM for a number?

Simple!
They calc how much fuel (btu's) to make electricity. Their formula is defective because if fails to factor in the TON of electricity ... just to MAKE/REFINE fossil fuel ... whether it's coal, oil, gasoline, or natural gas. Then, if you have to factor in running the (trillion dollar) MILITARY all over the world, to keep the toxic explosive fuel running ... just so we can keep the trillion dollar military machine running all over the world ... well ... we don't want to go down that road now, do we. ... oh, did I mention our Leaf will be charged via our PV panels?

Actually, they calculate the amount kWh of energy contained in a gallon of gasoline, not the amount of electricity that can be generated from that gallon (most generators are about 15% eficient). The formula is a straight conversion from input electrical energy used to charge the car to the amount of energy contained in the most energy-dense form of gasoline (not RFG). It does not factor in any well to pump or electrical generation energy losses in the calculation. The cost per year is based on $.12 per kWh for electricity.

 

[SanDust]

How does the EPA come up with 73 miles for "range"?
Do they have a specific test?
Or, perhaps just ask GM for a number?

The same way they'll get the range for every electric vehicle. The procedure is laid out in the Federal Register. You put the car on the dynamometer, find the range for the City Cycle, find the range for the Highway Cycle, put them together 55%-45%, and then deflate the result by 30% to reflect the range you'll get in the real world.

FWIW until the 2011 model year this is the same procedure that manufacturers of ICE vehicles used. They had a choice of either using the new five cycle test or of using the two cycle test with deflater. Since there is no five cycle test for an EV you use the alternative.

If the sticker on an ICE vehicle said 35 MPG, and that's generally what you got, then the 73 mile range will be realistic. If you got more than 35 MPG you'll get more range. If you got less than 35 MPG you'll get less range. The FTC sticker just doesn't use the deflater so its mostly aspirational.

 

[vkruger]

Would't the deflator for an EV be much less than the 30% of an ICE? The relative efficiency curves are much different.

 

[SanDust]

I'm betting it's near 30 or and actual 30 kwh, I'm sticking to that prediction.

The mini-E had the same efficiency rating as the Leaf. 34 kWh per hundred miles. 102 MPGe City and 94 MPGe Highway. 99 MPGe combined but 98 MPGe when rounded down using raw numbers. Basically no real difference (which is a little disappointing actually).

Using the same procedure as used for the Leaf, the mini-E range was rated at 100 miles, which it got with a 35 kWh pack of which roughly 30 kWh was available.

If the mini-E needed 30 kWh out of a 35 kWh pack to go 100 miles, and it's slightly less efficient than the Leaf, then, assuming the charging losses are about the same, the Leaf is using roughly 21.9 kWh to get its 73 mile range. Maybe 21.5 kWh because it's slightly more efficient. (The 34 kWh per 100 mile number is wall to wheels so battery to wheels complicates things slightly but it's the same for both cars so it washes).

 

[SanDust]

Kinda curious as to how GM could announce the volt getting 230 mpg but the Leaf only gets 73... but then again. The volt announcement was updated wasn't it?

GM got the 230 MPGe number the same way Nissan got its 367 MPGe number -- by using the CAFE calcualation for MPGe. The CAFE calculation is different than the sticker MPGe calculation. The CAFE calculation is considerably more complex and considers generation, distribution, and transmission losses, but it also gives a bonus, mostly having to do with the benefits of having a point source for emissions and pollution. The net result is that a gallon of gas is considered to have 82 kwh of energy. That pumps the MPGe number for EVs up.

So the short answer is that the Volt's 230 MPGe number should be compared to the Leaf's 367 MPGe number. FWIW both were based on the City Cycle.

 

[lne937s]

Would't the deflator for an EV be much less than the 30% of an ICE? The relative efficiency curves are much different.

Agreed. The big impact on EV range (climate control) is already included in the EPA estimate before the deflator. This probably explains why virtually everybody test driving the LEAF is beating the EPA sticker (even those trying to drive it as irresponsibly as possible to drain the batteries as fast as possible).

I think the FTC sticker actually has some validity here...

 

[Yodrak]

You are correct. Regular unleaded gasoline contains 114,100 BTU/gallon. Electricity contains 3,413 BTU/kwhr. That works out to 33.4 kwhr/gallon.

To get the 33.7 number gasoline would have to contain 115,000 Btu/gallon. I don't know what formulation gives that number.

In my opinion EPA is making a big mistake basing their calculations on 33.7kWh equivalent in a gallon of gasoline. This value sounds too high. I need to check this more, but I believe this value may be equal to the raw chemical energy of a gallon of gasoline.

 

[hill]

Actually, they calculate the amount kWh of energy contained in a gallon of gasoline, not the amount of electricity that can be generated from that gallon (most generators are about 15% eficient). The formula is a straight conversion from input electrical energy used to charge the car to the amount of energy contained in the most energy-dense form of gasoline (not RFG). It does not factor in any well to pump or electrical generation energy losses in the calculation. The cost per year is based on $.12 per kWh for electricity.

Yea, I did say that backwards, didn't I
In any event, as both you and I alluded, there are NO well to pump calc's factored into the EPA's voodo formulas ~ so it's a fiction, pretty much. And the fiction favors the oily industry ... even before one begins to calculate the amount of KWh's it takes to bring the gallon's KWh's to market. Gee, go figure. As for electricity line loss ... folks with PV on the top of their homes - they don't really have that issue as part of their reality ... so that's a good thing!

 

[thimel]

While its true that the EPA calculation of MPGe is a strict BTU comparison of electricity and gasoline and does not include the energy needed to produce the gasoline, it also does not include the energy needed to produce the electricity. This of course, depends on the source of the electricity and is difficult to define for solar or hydro, but for natural gas, oil or coal production of electricity, the efficiency is typically around 50%, meaning that twice as many BTUs of fuel are burned as electricity is produced. The rest of the energy is normally wasted. There is also several percent lost in transporting the electricity via the grid.

 

[Herm]

The 30% adjustment factor of the LA4 cycle is well known in EV circles, from previous experience, for the average driver and using AC. It does not mean you cant achieve the LA4 range or even exceed it Hypermilers will aproach 200 miles of range with the LEAF.

 

[Herm]

Sheez posted too quickly.. I believe 73 miles is probably what most people will get.. if they charge their battery up to 100%. If you use the routine long life 80% charge then you get 58 miles, still plenty for most people.

 

[TimeHorse]

Sheez posted too quickly.. I believe 73 miles is probably what most people will get.. if they charge their battery up to 100%. If you use the routine long life 80% charge then you get 58 miles, still plenty for most people.

but not for me; I need 75 mi per day. 73 would kill me out the gate, never mind 5 years from now. And I live where we have seasons.

Whatever, I'll just keep my ICE as backup and hope that I can ECO-mode and Hypermile the difference.

 

[kmp647]

Sheez posted too quickly.. I believe 73 miles is probably what most people will get.. if they charge their battery up to 100%. If you use the routine long life 80% charge then you get 58 miles, still plenty for most people.

but not for me; I need 75 mi per day. 73 would kill me out the gate, never mind 5 years from now. And I live where we have seasons.

Whatever, I'll just keep my ICE as backup and hope that I can ECO-mode and Hypermile the difference.

Timehorse, pm me or email me, I called dominion yesterday and tried to get info on t1 and ts
schedules and a TOU meter for my detached garage. What fun, these prople have no idea they are actually selling electricity or how much it costs

Kevin in VA

 

[Yodrak]

You've got the right idea, but the average efficiency for electricity generation is around 35%, significantly less that 50%. The rest of the energy in the fuel is lost as heat in the exhaust gases (for fossil fuel plants) and heat in the water used to condense the steam that drives the turbines back to water (for fossil and nuclear plants).

Combined cycle generating units, a combustion turbine coupled with a heat recovery steam generator and steam turbine, typically burning natural gas, can exceed 60% efficiency. Fossil steam units, typically burning coal but in some areas natural gas, can approach 38% if operated as base load generation (constant ouput at or near full load), but average more like 33% efficient because they are often required to reduce output when electric demand is low. Nuclear steam units are about 33% efficient.

While its true that the EPA calculation of MPGe is a strict BTU comparison of electricity and gasoline and does not include the energy needed to produce the gasoline, it also does not include the energy needed to produce the electricity. This of course, depends on the source of the electricity and is difficult to define for solar or hydro, but for natural gas, oil or coal production of electricity, the efficiency is typically around 50%, meaning that twice as many BTUs of fuel are burned as electricity is produced. The rest of the energy is normally wasted. There is also several percent lost in transporting the electricity via the grid.