The first fire occurred March 18 in the battery pack of a Mitsubishi i-MiEV (known in the US simply as the i) at the company's Mizushima factory. The pack overheated, causing a 98-minute fire in which no injuries or building damage occurred. The accident may have been caused by what Mitsubishi calls "a change in the manufacturing process of the battery supplier." As a result, the company is calling fleet-vehicle operators with i-MiEVs whose batteries were made under the same process as those that overheated and is working on a possible fix.
Meanwhile, on March 21, a battery pack in Outlander PHEV overheated at a Yokohama dealership. About 80 cells within the battery overheated, damaging one of the three blocks of cells in the battery and causing the unregistered car to not be able to run. Mitsubishi says owners of the Outlander PHEV should hold off on external charging until a further investigation of the cause of the incident is conducted. Mitsubishi says the fire will not delay the plug-in Outlander's US launch and there is no official word if a recall will be required for either vehicle. Mistubishi has sold 4,000 Outlander PHEVs in Japan.
Mitsubishi uses battery cells that have an indirect connection to the fires in the Boeing Dreamliner earlier this year, the batteries that Tesla Motors CEO called "fundamentally unsafe." Mitsubishi't cells come from Lithium Energy Japan, a joint venture between Mitsubishi and GS Yuasa that was started in 2007. GS Yuasa makes the batteries for the airplane, but Boeing says it will not stop testing the Dreamliner in light of these fires.
Mitsubishi's press releases on the incidents are available below.
Tokyo, Japan March 27, 2013 - Mitsubishi Motors Corporation (MMC) reports one instance of a fire occurring in one of the drive battery packs used for MMC's electric vehicles (EV) on March 18 at its Mizushima Plant in Okayama prefecture in Japan. Details are as follows:
1. Description of Occurrence
At around 8:15 pm on March 18, one of the 16kWh drive battery packs used in the i-MiEV (lithium-ion battery) overheated in the battery inspection room at the EV assembly factory at the Mizushima Plant. The drive battery pack started to smoke, and then ultimately caught fire one hour after. The battery pack was charging connected to charge-discharge inspection equipment as part of final inspection. The plant contacted the fire department and the fire was extinguished at around 9:53 pm on the same day.
No injuries were caused. Although one drive battery pack and a charging cable for the inspection equipment were burned out, there was no damage to the building or to the inspection equipment itself. However, per instruction by the fire department, equipment involved in the fire (charging/discharging testing equipment) have currently been shut down.
3. Investigation into Cause
Although the cause has yet to be fully determined, a possibility includes a change in the manufacturing process of the battery supplier, resulting in defects. MMC is decisively moving forward with continued investigations along with the supplier to determine fully the root cause. The number of applicable Japan-specification vehicles, which employ the same drive battery pack assembled in the aforementioned modified manufacturing process totals 68 units, used by fleet customers. Another 45 drive battery packs have been shipped as spare parts.
4. Further Investigation
MMC is currently conducting further investigations to determine the root cause.
MMC will contact its fleet customers with vehicles that contain the same drive battery packs to explain the situation and also check their vehicles. MMC will also investigate the usage of the drive battery packs for spare part use.
Tokyo, March 27, 2013
Mitsubishi Motors Reports One Instance of a Melted Battery Cell in an Outlander PHEV and Proactive Measures
Tokyo, Japan Wednesday, March 27, 2013 – Mitsubishi Motors Corporation (MMC) reports one instance of a melted area in a part of the drive battery pack of an Outlander PHEV caused by an overheating battery cell. Details are as follows:
1. Description of occurrence
On March 20, 2013, an Outlander PHEV was charged fully from a standard outlet then stored at a dealership in Yokohama. The next day (March 21), the dealer personnel attempted to move the vehicle from storage for delivery to a customer (prior to registration) when it was found that it would not move. In addition a strange odor was detected around the vehicle. Upon checking the underbody of the vehicle, signs of melting were observed on the part of the drive battery pack.
When the battery pack was examined by the supplier, it was found that one of the battery pack's 80 cells had overheated, melting adjacent cells. The 80 cells in the drive battery pack are divided and set into three "blocks" within the drive battery pack. Examination found that only one of the three blocks sustained any damage.
No damage to the dealership facilities nor injuries occurred. Outside of the drive battery pack itself, there was no damage to the vehicle.
3. Investigation into Cause
The battery in question was moved to the battery supplier for prompt joint investigation with the supplier into the cause. Although the cause has yet to be fully determined, a possibility includes a defect in the manufacturing process of the battery supplier, resulting in defects in the batteries. MMC is moving forward with continued investigations to determine fully the root cause.
This incident of melting in a drive battery pack happened before the vehicle was registered (and therefore drivable on the road). As of March 21, no cases of drive battery packs melting nor catching fire have ever occurred.
4. To all Mitsubishi Motors Customers
This incident occurred after the battery was fully charged for the first time. Mitsubishi Motors is decisively pushing forward with investigations into the root cause. Based on the above information Mitsubishi Motors suggests that Outlander PHEV drivers refrain from using external charging or Charge Mode until the cause is found. In addition, dealers will be contacting Outlander PHEV customers regarding use of their vehicle as well as responding to customer inquiries.