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Battery



Information

The battery consists of laminated lithium-ion cells with lithium manganate cathodes [1]. The battery modules are currently manufactured at the Automotive Energy Supply Corporation (AESC) operation in Zama, Japan, which is a joint-venture of Nissan Motor Co., Ltd. and NEC Corporation. The battery contains around 9 lbs of lithium [2].

The Leaf has a range of 100 miles, based on the LA4 EPA Urban Dynamometer Driving Schedule (UDDS). Owner can pre-heat or pre-cool car prior to unplugging from charger in order to maximize range [3]. There is more info on driving range on the Leaf Information Center Wiki.

A "SOC Check Sheet", showing VIN & number of SoC bars at "port of entry" shows an U.S. delivery LEAF delivered with 50% state of charge:
Socsheet.jpg


Table showing LEAFs' GIDs/voltage at 80%/100%, odometer reading, etc.
GIDs volts SoCal Leafs.png


Battery specs: dimensions, voltage, construction, capacity, chemistry.


Nissan will manufacture the battery at a new battery plant in Smyrna, Tennessee, which broke ground on May 26th, 2010. The plant will come on at the end of 2012 and will make 200,000 battery packs a year [2].

2012 LEAFs will come with a battery heater as standard. Here is a diagram of the battery heater, from 2012 LEAF service manual: 1-6, 8, and 9 are heaters, 7 is the heater relay unit :
Batteryheater.png

  • 12V battery alternative : Elite Power's "BS-LFMP40AH (4-cell pack)":
    Elite Power LiFeMnPO4 battery 12V40AH.jpg
    • Nominal Voltage: 12.8V (4X3.2V)
    • Nominal Capacity: 40 Ah
    • Chemistry: LiFeMnPO4
    • Operation Voltage Range: 11.2 to 14.4V
    • Weight: 6.6 kg or 14.6 lbs
    • Dimension: 125X208X180 mm or 4.9X8.2X7.1 in
    • Max Charging Current: 3C
    • Max Discharge Current: 3C (continuous) / 10C (pulsed)
    • Cycle Life : >2000 (80%DOD)
    • Operating Temperature: -20 to 65 C or -4 to 149 F
    • Self Discharge Rate: <3% monthly
    • Accessories included: jumpers, bolts or rivets, washers, split washers and cell covers

Battery Temperature Gauge

The Li-Ion battery gauge is a 12-segmented gauge with very coarse granularity. Below are the battery temperature ranges that may be indicated by a given number of bars. The specific values shown are interpolations done by RegGuheert from a graph in the service manual. Note that there is a great deal of overlap. Consider, for example, a battery temperature of 80 degrees Fahrenheit. This could be displayed as 5, 6, or 7 bars. Nissan explains this by stating that the number of segments is corrected "according to the battery capacity."

It is unclear from their description how the correction is applied, or in which direction. It has been hypothesized that the low end of the range would apply to a new battery and the high end to a degraded battery, but this has not been confirmed. It has also been suggested that the LEAF may be estimating the temperature inside the cells with a crude thermal model, and adjusting the estimate based on known degradation. This would imply that a new battery would be at the high end of the range.

Battery Gauge Segment / Temperature Chart[4]:

Segments Min Degrees C (F) Max Degrees C (F)
12 56 (133) none
11 52 (126) 59 (138)
10 49 (120) 56 (133)
9 47 (117) 52 (126)
8 36 (97) 49 (120)
7 23 (73) 47 (117)
6 10 (50) 38 (100)
5 -3 (27) 27 (81)
4 -5 (23) 15 (59)
3 -8 (18) 4 (39)
2 -12 (10) 2 (36)
1 -15 (5) -2 (28)
0 none -5 (23)

As one can see, segments 4 through 7 can potentially cover a very wide range of temperatures from -5C to 47C. The top 2 segments and bottom 2 segments are colored red and blue respectively to indicate very high and very low battery temperatures. It is recommended to NOT quick charge the battery when the battery is in the red zone [5].

Battery Capacity Loss

Battery capacity loss stuff has been moved to this page.

Li-Ion Technology

Cost

  • Some information on the battery pack's cost:
    • Excerpts from businessweek.com article, May 14, 2010:
      "Nissan Motor Co., which will start selling its Leaf electric car this year, aims to cut the cost of the vehicle’s lithium-ion battery pack to less than $370 per kilowatt-hour to make a profit from the model." (US$8,928)
      "Nissan’s battery currently costs about 1.05 million yen, or $472 per kilowatt-hour, according to Takeshi Miyao, an analyst in Tokyo at auto consulting company Carnorama." (US$11,328)"
    • green.autoblog.com article:
      "A couple weeks ago, the Times of London reported that the battery in the Nissan Leaf cost the automaker around $9,000 to produce.
      "Mark Perry, Nissan's chief product planner for North America, tells The Wall Street Journal that the actual cost is a little less than $750 per kilowatt hour, bringing the total to just below $18,000."


Range/Power Consumption


Real-World Range/Power Consumption Experience

Range

Power Consumption

Battery Capacity Behavior

  • The twelve smaller segments at far right of the battery gauge represents the battery's current maximum capacity. As the battery's capacity degrades, these bars disappear one by one. This table shows the approximate battery capacity represented by each bar [6]:
Segments Retained capacity (%) Note
12 85 or more T12
11 85 T11 Value at which segment 12 turns OFF
10 78.75 T10 Value at which segment 11 turns OFF
9 72.5 T9 Value at which segment 10 turns OFF
8 66.25 T8 Value at which segment 9 turns OFF
7 60 T7 Value at which segment 8 turns OFF
6 53.75 T6 Value at which segment 7 turns OFF
5 47.5 T5 Value at which segment 6 turns OFF
4 41.25 T4 Value at which segment 5 turns OFF
3 35 T3 Value at which segment 4 turns OFF
2 28.75 T2 Value at which segment 3 turns OFF
1 22.5 T1 Value at which segment 2 turns OFF
0 16.25 T0 Value at which segment 1 turns OFF

Battery Bugs/Problems

Emergencies

  • In case of a collision (air bag deployment, etc.) or certain system malfunctions, an emergency shut-off system shuts off the high voltage from the Li-ion battery. [7]


12V Battery

The LEAF has a 12V battery, also known as the "housekeeping battery". It performs the following functions:

  • Initial switching of main battery power. Since the 12V battery supplies power to "switch on" the main battery, a LEAF with a dead 12V will not start and will have to be jump started, that is, it has to receive 12V power from an external supply.
  • Initialization of the charging process.
  • Providing power to 12V accessories such as the entertainment and navigation system, lighting, horn, warning chimes, etc. because it is not efficient to "step down" the main battery voltage to 12V to power these low-current-draw accessories.

The 12V battery is automatically charged when:

  • On power on, the VCM determines that the 12V battery's voltage is too low [8].
  • When vehicle is left for a long period of time: the VCM keeps track of the no-operation duration with its internal timer. If the no-operation duration reaches 120 hours, the VCM automatically charges the 12V battery for 5 minutes. The VCM resets the no-operation time when the vehicle satisfies one of the following conditions [9]:
    • The vehicle is in READY state (green "car with arrows" icon) more than 5 minutes.
    • Normal charging has continued for more than 5 minutes.
    • Quick charging has continued for more than 5 minutes.
    • Timer air conditioning or remote air conditioning has continued for more than 5 minutes.

Medium to Long-Term Storage

12V Battery Storage

The relatively high power draw of the LEAF's electronics in standby mode and the VCM's periodic charging function during prolonged non-operation lead to substantial battery cycling that is very stressful for the 12V lead-acid battery. Leaving the LEAF plugged in leaves more computer systems running which result in a higher load on the battery, so do NOT leave the car plugged in if leaving the car for more than a couple days, otherwise you are likely to return to a dead car that needs a jump-start. For storage longer than a couple weeks, it is recommended to maintain the 12V battery charge with a Battery Tender or equivalent.

HV Battery Storage

The owners manual recommends charging the car in long-life mode (80%) and storing the car that way. But the general consensus is that storing the car with a SOC between 40-50% (4-6 bars) is even better for maintaining battery capacity. In general, storage of lithium batteries above 40% SOC results in an increase in capacity loss over time. DO NOT STORE YOUR LEAF FULLY CHARGED, ESPECIALLY IN HOT WEATHER! Storing lithium batteries fully charged and at high temperatures causes the fastest rates of capacity loss over time.

The LEAF will not lose any significant charge even when stored for months, especially if the 12V battery is disconnected.

How to store your LEAF when going on vacation

Aftermarket


  1. http://www.eco-aesc-lb.com/en/product.html
  2. 2.0 2.1 http://green.autoblog.com/2010/05/27/details-on-nissan-leaf-battery-pack-including-how-recharging-sp/ "Details on Nissan Leaf battery pack, including how recharging speed affects battery life"
  3. http://www.nissanusa.com/leaf-electric-car/index?intcmp=.Electric_Car_Reserve.Promo.Homepage.Home.P2#/leaf-electric-car/faq/top/range Nissan LEAF FAQs
  4. Nissan LEAF Service Manual April 2011 revision, page MWI-21
  5. Need reference.
  6. Nissan LEAF Service Manual, page MWI-23
  7. http://www.nissan-techinfo.com/refgh0v/og/FRG/2011-Nissan-LEAF-FRG.pdf 2011 Nissan Leaf First Responder's Guide, page 10
  8. Nissan LEAF Service Manual, page EVC-45
  9. Nissan LEAF Service Manual, page EVC-45