A pure electric car with a lithium-ion battery can lose as much as 57% of its range when the temperature dips and 33% when the mercury rises, a new study, conducted by the AAA (American Automobile Association) Automotive Research Center, says.
The research provided hard numbers for a phenomenon that has long been discussed anecdotally -- that is, that big temperature swings can pose range problems for electric vehicles (EVs). “We knew there would be a change,” John Nielsen, managing director of engineering for AAA, told Design News. “What surprised us is that the (range reduction) is inherent in the design of the battery. It doesn’t matter whether you buy ‘brand X’ or ‘brand Y.’”
AAA tested three electric vehicles -- a Ford Focus EV, Mitsubishi i-MiEV, and a Nissan Leaf -- on dynamometers and learned that all three were strikingly similar. Based on tests conducted at 75F and again at 20F, the accumulated numbers for the three cars showed that the average driving range dropped from 105 miles to 43 miles. Similarly, the engineering team tested the three at 75F and 95F, with the average range dropping from 105 miles to 69 miles at the higher temperature.
Although AAA did not test at temperatures below 20F, Nielsen indicated that the driving ranges would have dropped further in temperatures of -20F and -30F, which occurred in northern regions of the US during the past winter. “It certainly wouldn’t be a linear decline,” Nielsen told us. “But in very cold weather, there would definitely be another drop.”
One of the reasons for the decrease in range in cold weather is the use of interior heaters, Nielsen said. And at some point, that particular effect would be unchanged, no matter the exterior conditions. “During the test, we set the interior temperature at 70F, and the heater is only capable of having so much (current) draw on the car,” he explained. “That (current) draw would be the same, whether the outside temperature is 20 or minus 20.”
AAA, which has been a consistent advocate of electric cars, offered three recommendations for EV owners: Store the car in a (heated or unheated) garage; use the seat heaters instead of the cabin heating system (creating less draw on the battery) when possible; and be aware of the real range numbers in cold and hot weather.
”This shows that when the weather changes, there’s always a range number to consider,” Nielsen told us. “And that number is going to be lower in Chicago than it would be in San Jose.”
Been busy and my email telling me of updates here is down.
I've been talking about anything that will reduce the range in the cold (which is what they are trying to measure), it is only you trying to limit it to one item and then claim it falsifies an apparently broader claim.
OK, I'll play your game for the moment.
2kw/h X 2hr commute + 4kw or 20% of the Leaf battery.
So we assume 40-50 mph on the commute. My rural commute is approx. 42 mph (17.5 miles, 25 min.) Plausible.
Yay! You get your 20%.
But wait a minute. Barry says he is losing 25% of his range and he is using his iMiev's defroster only 15 sec in every 5 minutes (5% of the time). Negligible for our purposes. 25% range loss from non-heater sources (no, I don't know what). Real world test so to speak.
Say his evil twin Bruce likes to keep warm and toasty. He runs the heater full blast and dumps Jerry's 20% heater loss on top of the 25% real world non-heater loss that Barry had.
Dang, we are talking 45% range loss here. OK, since the range is shrinking Bruce won't have the full two hours to run the heater. Call it 40%. AAA's numbers are starting to look more realistic.
Now let's consider a slower urban commute, stoplights, congestion etc. 20 mph average.
Heater runs when the car is stopped-ambient air cools the cabin at the same rate even if the car isn't rolling and using motive power. 4 hr commute double the heating time. Range is sinking fast.
Jerry, you picked some numbers to try and create an artificial scenario to "prove" your point. It is a no go.
And simply trying to narrowly define the argument to avoid dealing with information that doesn't support your point (Barry's range, my calculated range drop with IC vehicles) looks pretty obvious to me. I suspect that when people drop out of these wrangles with you, you assume you have won the arguement. Secret is buddy, they may just get sick of the game and playing with somebody that has their own stacked set of rules.
Funny thing is that by driving me to look closer at the problem you have lead me to be more comfortable with this studies numbers rather than less so. Ironic, no?
So, have we beat this sufficiently to death for your taste?
I was talking about the EV heating numbers cutting range, the point we were talking about.
Don't you know how much power it takes to A/C a car/EV? Shouldn't before telling someone else they are wrong? Facts are EV's should only use 2kw At MOST for heating on say a 24kwhr pack, No? Please explain higher use in real numbers? I A/C my eff home on 600 watts/hr though only runs 2-6 hrs/day in Fla. So I hope you can A/C or heat pump heat an EV for 2kwhr.
Thus the math you were suppose to do showing how this small load, well under 8%/hr and rarely do you drive an EV over an hr, cuts range like they or you said?
So let's stick to the question rather than try side issues. So do the math and explain it to me how heating or A/C cuts range so drasticlly from that load.
AAA and AAMA even faught seat belts!! Look it up, they have been against any car mandate since at least the late 50's. This is known to anyone who bothers to look. Why else would they be against air bags, 5 mph bumpers, setabelts, etc?
And here they are against the EV mandate, no? Their obvious by how badly they cooked the books proves that, no? Go read their PR on car mandates if you don't believe me. Read them on 5 different car mandate things and you'll notice a pattern with a hard big auto bias.
Seems like an opportunity for better design. The AC can be used as a heat pump to give about 3 times the heat per KWH than resistance heating. The motors, transmissions and controllers must all generate heat, and that should be used to keep the batteries warm. Insulate the battery packs, turn on the gas generators in hybrids to warm the batteries.
Heat may be a bigger problem, but the AC could be oversized to cool the batteries, more fans, heat driven refrigerator... The question is if the extra energy used increases the total range. Solar panels might bring back a few percent, assuming hot days are sunny too.
"On the Prius wouldn't the heat from the engine through the heater be just waste heat and therefore free? "
There's a little bit of free heat. But if I turn the cabin heat up more (say to 70F with 0F outside), the gas engine has to run hard practically all the time and the mpg drops to the 35mpg range. This is noticed on the highway. In town it drops to 32mpg with all the stops and the gas engine always running. Thus I don't use the heat much.
"By the way, have you run E10 in the Prius? "
No thanks. I'm avoiding that like the plague. Theoretically mpg should drop. I wish they would remove the 10% ethanol in today's gas; what a waste in mpg! I'm always looking forward to the summer gasoline; much better mixture.
On the Prius wouldn't the heat from the engine through the heater be just waste heat and therefore free? The fan would draw a little but I'm not seeing the savings here with not running the heater. Your drop is closer to the 20% Jerry was assuming as normal. I do wonder if hybrids do typically see a greater drop. No theory as to why at the moment, pure speculation.
By the way, have you run E10 in the Prius? I have heard from other owners that Ethanol blends really drop the mpg, more so than in a conventional IC car. Any thouhgts?
"SO what is the mileage drop for the Prius? I wonder if hybrids see a greater swing (no idea why they would, just wondering). "
My 2009 Prius easily gets 49mpg in the summer with a 12 gal tank. Theoretically I can go 588 miles.
But in the winter, I get 40mpg (using hardly any heat) with a 10 gal tank. Theoretically I can go 400 miles; a 32% drop. I don't think other hybrids use a bladder tank. Toyota wanted to minimize gas- filling emissions in the winter but that sure is a hassle with reduced range. I would get MORE than a 32% drop if I used my heater heavy duty. But I extend my EV tricks to the Prius to get my range up. At least with a combustion engine, its heat raises the cabin temperature a little more; just a byproduct of inefficiency that's nice in the winter.
And thus for winter range drop, my prius is worse than my EV.
-No more oil changes, spark plugs, other maintenance, etc.; I'll sure miss that... ; -- )
My wife tracks the mileage closely, just reviewed the Toyota. The Seinna drops from 22 to 20-21 in the winter, the ski box was on for awhile this winter and knocked it into the 18-19 range. Math seems to be working pretty well here. Haven't run the numbers on the Honda in a while ('95 Oddy). Actually my mileage about doubles in the summer but I'm on my VFR then, acceleratin picks up just a bit too.
Jerry, honestly buddy lighten up. I'm OK with your opinions but frankly you seem pretty testy these days. You jumped to the assumption that I hadn't run the numbers pretty quickly.
I don't know where you are getting your kwhr estimates, anyone can just pop out some numbers that, if taken at face value, will give the result they want..
Tell you what, explain to Barry why his iMiev is dropping 25% of it's range even with the efforts he makes to avoid heater use. Your "at most 20%" was for for EVs if you look at your own post. Barry's experience seems to belie your confidant prediction. It makes the AAA numbers, where they just run the heater like a typical driver, seem pretty plausible. As plausible as your estimates.
First I said at most 20%. And when you add up warming up a gas car it's even worse than EV's fpor them. I suggest you actually measure your winter vs summer driving and you'll find you lose more mpg than you think.
I'm going by actual measurments/ studies of EV's and gas cars for 40 yrs vs feelings thus why I know it's rigged as it's a far outlier compared to the massive data already in. EV's have been around 120 yrs now, it's not their first rodeo.
Again how is using 2kwhr at MOST heating or A/C cut EV range with a 24kwhr pack? Please answer that question. Isn't it obvious? Do the math. How can it not be rigged? Waiting for your answer?
"You use a lot of specialized (and clever) methods to reduce heater use and yet you see a 25% drop in range. " Yep. And I get a 32% drop in range on my 2009 Prius in the winter. Half of that is because of gas tank/bladder shrinkage.
"Curious, where do you live? "
I live in Idaho Falls, ID. It's winter 6 months of the year and summer 6 months of the year. So yes, we see cold for a while.
"what is the typical "off" interval"
Mine is about 5 minutes with 2 people in the car. Also if we leave the window slightly cracked we can go w/o using the defroster. But we definitely need the coats buttoned up and a ski mask on! It's just like snowmobiling (but w/o the wind chill).
Some cars are more reliable than others, but even the vehicles at the bottom of this year’s Consumer Reports reliability survey are vastly better than those of 20 years ago in the key areas of powertrain and hardware, experts said this week.
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