Heat treatment fries bugs – not EV battery

A Nissan Leaf has passed a biosecurity heat treatment test without any battery damage.

In fact, a full report shows the 24kWh 2013 Leaf tested at Ports of Auckland passed with flying colours, despite temperatures of around 80 degrees Celsius recorded by some of the eight sensors.

Concerns about whether electric vehicle lithium-ion batteries would stand up to the heat treatment used to kill pests like the brown marmorated stink bug prompted the Imported Motor Vehicle Industry Association (VIA) to order its own tests.

Using Genera and BioVapor facilities at the ports, the Leaf was heated to the required 60 degrees Celsius treatment level, the whole heating process taking about 45 minutes – considered longer than normal.

The vehicle had to be held for 10 minutes at 60 degrees once the last sensor probe reached 60, and in the build-up 80 degrees was reached by some probes, VIA technical manager Malcolm Yorston says.

Yet three sensors in the Leaf’s lithium-ion battery showed the highest temperature there was 36.6 degrees Celsius, well within the optimal 20-40 degrees operating range, he says.

“The battery temperature also dropped pretty quickly within a couple of hours after testing finished to about 20 degrees,” Yorston says.

“We’re very happy with the result,” he says. “It alleviates a lot of the concerns we had.”

No other parts of the Leaf showed any ill effects either.

Yorston says many other EVs have a similar battery configuration to the Leaf, but a test on a differing Mitsubishi i-Miev is now planned.

A final report on the Leaf’s full results has just been released, and Yorston says it will be sent to key players in the industry, such as the NZ Transport Agency which had observers at the test.

Read the full test report here

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