Does the new 62 kWh LEAF battery have “an additional fan” for cooling?

 

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The new 62 kWh Nissan LEAF battery pack.

Ever since the first Nissan LEAF was built way back in 2010, electric vehicle enthusiasts have debated the merits and trade-offs of active versus passive cooling for its battery pack.

The LEAF’s battery pack has so far been passively cooled meaning that the cells cool simply by radiating their heat into the overall battery pack. The pack itself is just a metal box that is more or less sealed from external air flow. The outer surface of the pack radiates heat and air flows past it while driving or when stopped on a windy day.

People sometimes say the LEAF pack is “air-cooled” but there is no fan blowing cabin air into the pack as there is on some other cars like the Hyundai Ioniq Electric. The LEAF also has not had a fan blowing air onto the outer surface of the pack. Many other electric vehicles with larger battery packs use a liquid-cooling system that runs a water and glycol mixture through chilling plates under pouch cells or through ribbon tubes that contact cylindrical cells as in Tesla vehicles.

Battery packs can build up heat from fast highway driving, fast DC charging, or just from sitting in a sunny parking lot in a hot climate area like Arizona. Excessive heat can cause batteries to degrade and lose energy capacity faster than if kept at cooler temperatures. Ideally, the lithium ion batteries used in modern EVs prefer temperatures similar to what people like — somewhere above 68F but not much hotter than 90F.

A recent article from electrive.com on December 4 exclusively reported details from a private briefing given by Nissan in Europe to some of its dealers. According to the report, Nissan would reveal a new “LEAF e-Plus” at CES 2019 in Las Vegas that had 60 kWh of usable battery capacity, near 100 kW charging capability, but no liquid cooling for the battery pack.

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Nissan Senior VP Denis Le Vot briefs the media about the new LEAF at CES 2019.

When the reveal actually happened at CES on January 8 those details all proved to be true. On the other hand, the article predicted that this new LEAF would use battery cells from LG and Nissan denied this saying that the cells were not from LG but from their own AESC subsidiary.

That leaves one more key item from the article. It said:

Supposedly, Nissan is trying to tackle the [battery heat] issue, at least a little. As with the electric transporter e-NV200, an additional fan is to give the battery a breath of fresh air during the DC charging process.

The e-NV200 is a small commercial van derived from the gasoline-powered NV200 but with the powertrain taken from a Nissan LEAF. It has a unique battery derived from the LEAF that contains the same cells reconfigured into a different pack shape that includes an internal fan that blows air over a dedicated A/C chiller inside the pack to actively cool the inside of the pack.

“Due to more compact packaging and because e-NV200’s duty cycle is likely to be quite different to LEAF – it is anticipated that the vehicle will be operated intensively during the working day and there will be greater use of Quick Chargers to minimise down time – cooled air from the vehicle’s heating and ventilation system is channelled over the battery cells to ensure optimum charging conditions at all times”, according to a Nissan media release from 2014.

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The Nissan e-NV200 all-electric commercial van.

At the new LEAF reveal in Las Vegas, Nissan officials told some reporters that the pack would remain passively cooled as in previous generations of the car. So, the report of a new cooling fan appeared to be untrue. Then this happened:

A similar tweet from Nissan’s official UK twitter account had also been sent a few days earlier on January 9:

A few automotive discussion forums and online articles have picked up on this and a popular European electric vehicle news blog retweeted NissanUK’s claim.

So, does the 62 kWh Nissan LEAF have an additional fan to help dissipate high temperatures? Spokespersons for Nissan USA and Nissan Europe both told Electric Revs that the answer is no.

“I can confirm to you that no additional fan has been added in any version of the LEAF e+ battery and that tweet was a mistake”, said Xavier Audoin of Nissan Europe, “The thermal management of the LEAF e+ is similar to the 40 kWh battery.”

 

 

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Categories: Auto Correction

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9 replies

  1. Until they add liquid cooling they are killing batteries faster than any plugin automaker. The battery in a Tesla or Chevy Volt Bolt will last 10 times longer and that is sustainable. Without it they should never sell a LEAF in the Southern USA>

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  2. It’s confusing. Real tests will reveal if battery cooling is sufficient. Drilling additional vent holes comes with some risks….

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  3. Thanks Jeff for working to clarify this. Living in Phoenix, a passive cooling scheme is unacceptable to me. Perhaps it works great for cooler climates, but not an option for me.

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  4. As a UK questioner pointed out in the Twitter feed, a fan for cooling does not help warm the battery in cold conditions. A thermal management system can do both, cool or warm the cells for optimum performance in either hot or cold conditions. I fear Nissan has made a fatal mistake in the design of the new Leaf that will impact sales to the extent that a redesign of the battery pack will be required.

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    • I didn’t get into it for this article, but I assume the LEAF pack continues to have electric warming pads inside the pack to help out when the pack is very cold. I did not specifically verify this with Nissan (or write about it here) since my focus was on nailing down the cooling issues.

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    • Presuming the “fan” takes air from, or perhaps shares a heat exchanger with, the cabin HVAC system, it can both cool and warm the battery in accordance with the weather.

      Li-Ion batteries are efficient and don’t generate that much heat; the heat they do generate only becomes a problem when bottled up inside a package like the first-gen Leaf’s battery box. The heat is diffuse (generated uniformly throughout the pack) as opposed to concentrated like the power devices in the inverter. These are both attributes that favor air cooling as opposed to liquid. I do hope that Nissan has learned from the first-gen Leaf and included some thermal management in the new design, but I hope folks won’t reject anything other than liquid, since liquid adds a lot of complexity and failure points, while air has a pretty good chance of serving well in this application.

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      • There is no battery thermal management fan in any LEAF model. All LEAF packs, including the latest 62 kWh model, have closed packs that only use passive heat exchange through the metal outer skin of the pack enclosure.

        There is a fan and HVAC thermal exchanger in the closed battery pack of the e-NV200 van that uses a custom battery pack derived from the design of the LEAF pack and that uses the rest of the LEAF’s powertrain.

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  5. the history of Leaf batteries is not good. It makes it a no buy for me.

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