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How Much Range Does Your Leaf Lose If You Unplug It For 8 Days?

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2011 Nissan Leaf: One Year Drive Report

2011 Nissan Leaf: One Year Drive Report

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Remember Michael DeGusta, the guy who indadvertedly ‘bricked’ his oh-so-expensive Tesla Roadster  after storing it in an almost-empty state for nearly two months?

In the case of DeGusta’s Tesla, the car used most of the remaining charge trying to keep itself warm, but the story did remind us all of one simple thing: like any other rechargeable battery, an electric car’s battery pack will slowly discharge when left unplugged.

So, with some very crude scientific endeavor, we set out to see just how much range a 2011 Nissan Leaf would lose as a consequence of being parked up for eight days with a partial charge. 

An electric car battery pack turns electrical energy received during recharging into chemical energy. Then under use, it converts that chemical energy back to electrical energy to provide power to the car.

Disconnect a regular rechargeable battery to store it, and slow, internal chemical reactions take place within the battery which gradually discharges it. Leave an electric car unplugged for a while, and the same happens.

The rate of discharge depends on the type of battery. Typically for lithium-based battery packs, self-discharge is around 2 to 3 percent per month--though it varies with the specific cell chemistry used.  For nickel-based battery packs, self discharge can be as much 30 percent per month. 

2011 Nissan Leaf SL

2011 Nissan Leaf SL

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On paper that might sound easy to predict, but temperature, state-of-charge when unplugged, and battery age also affect the rate at which a battery self-discharges. 

On to our test case. After a 30-mile drive, we parked our Leaf at our local airport with an indicated 51 miles of remaining range. Over the course of the next eight days, we regularly checked the car’s state-of-charge remotely using Nissan’s Carwings service, gradually watching the predicted range drop.

During that time, daytime temperatures dropped from 68 degrees Fahrenheit down to the high 50s, while nighttime temperatures averaged 40 degrees. 

When we returned to our car, it told us we had enough charge to drive 45 miles, representing a 6-mile drop in predicted range over 8 days.

While that might seem more than the suggested 2-3 percent drop per month, self-discharge wasn't the only thing responsible the 6-mile drop.

Lithium-ion battery pack of 2011 Nissan Leaf, showing cells assembled into modules

Lithium-ion battery pack of 2011 Nissan Leaf, showing cells assembled into modules

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As with any car when it is switched off, some of the Leaf’s 12-volt accessories continue to consume power. Everything from the alarm to the battery monitoring and telematics systems consume power when the Leaf is switched off. 

Over time, this drains the Leaf’s on-board 12-volt lead-acid accessory battery, requiring the car to periodically charge it as needed through the 24-kilowatt-hour traction battery and DC-DC converter. 

What have we learned? 

In most circumstances, leaving your Leaf unplugged for a week or so with a moderate amount of charge will lose you a small amount of range.

But if you’re going away for longer, you should follow Nissan’s own advice and plug in the car, to make sure that you keep your Leaf’s battery warranty valid

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Comments (9)
  1. Why would one trust the range estimator's accuracy in this case
    but not elsewhere? Doesn't the estimator take into account ambient temps, etc in estimating driving range? Anything that the range estimator does take into account, and which has differed from initial estimate to the estimate made days later will provide invalid data as to loss of charge. Put a wattmeter on the battery - then you'll know exactly how much charge is lost. But even that will only be valid for conditions exactly like those used in the test.
     
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  2. I concur. It would be nice to have standardized tests for this type of thing so that more precise data was available to the customer.
     
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  3. Don't you have the solar charging panel on your Leaf? That should take care of the 12 volt system if there was any sun at aall?
     
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  4. I would have thought so too. Was it parked out of the sun, in lower levels perhaps?
     
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  5. How long before long term airport parking has charge terminals? I would settle for 120V, just enough to maintain the batteries. But long term parking in such a lot is a concern.
     
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  6. The telematics/carwings connection shuts down after 14 days to save energy. It happened to me already while I was away on vacation.
     
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  7. I recently left my prius parked outside while abroad for four and a half months through the winter,freezing temps and snow.The original eight year old 12v was flat but after overnight charge the car backed out of the drive on electric before the ICE started.The main battery registers normal on the display and still avgs 56mpg per tank.I might add this non use period happens every year but usually for two months not four plus.So whats happening here is it fear of the unknown for doubters or do I have an exceptional car?
     
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  8. Do you have a cooling system that runs when your car is off, to cool the lithium ion batteries on hot days, and to warm them on cold nights? Does your car have an always on telematics system which draws power when the vehicle is at rest? Is your car an EV?
     
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  9. The answer is no to all the above, my post was to point out what a lot of doubters of this technology always seem to mention ie the fragility of the batteries.In my experience this has not been a problem even though I have abused the system with extended down time and this on an eight year old Prius. I realize my result is not fully comparable to a full EV since there is more demand on that type system, however there are still those weary of even hybrids mainly because of the battery hence my post.
     
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