Tesla updates battery software after latest Model S fire

Tesla has released over-the-air updates to Model S and Model X battery cooling systems after two recent fires.

Tesla has beamed out an over-the-air update for the Model S and Model X to increase safe battery operation after an investigation into a Model S fire in a parking garage that was caught on video.

A surveillance video emerged in late April and quickly went viral, showing a Model S bursting into flames in a Shanghai parking lot structure; the blaze occurred when the car was not charging and appeared unprompted by any external factors. Tesla was reported to have sent a team to investigate the fire but has not commented on possible causes of the blaze, which looked more like an explosion. Industry observers quickly pointed to possible heat management issues with the car’s battery pack because the smoke and the subsequent fire emerged from the underside of the car.

The Shanghai Model S fire was followed by another Model S fire in Hong Kong earlier this month, in which the sedan caught fire under similar unexplained circumstances and required firefighters almost an hour to extinguish.

“As we continue our investigation of the root cause, out of an abundance of caution, we are revising charge and thermal management settings on Model S and Model X vehicles via an over-the-air software update that will begin rolling out today, to help further protect the battery and improve battery longevity,” Tesla said in a statement late last week.

Tesla vehicles use a cooling ribbon with glycol liquid woven around the individual cylinder-shaped battery cells, made by Panasonic, in its battery pack. The older Model S used one continuous cooling ribbon, snaking around the hundreds of individual cells and cycling glycol coolant in and out. A second-gen battery module, on the other hand, used two cooling ribbons and the battery cells were now attached to the cooling tubes by glue, which improved the effectiveness of the ribbon. The current Model 3 uses a further improved system of a total of seven ribbons of much shorter lengths to cycle coolant around the cells — a significant improvement over the original Model S cooling system design.

“Tesla battery packs are engineered with a state-of-the-art design so that in the very rare instance a fire does occur, it spreads very slowly and vents heat away from the cabin, alerting occupants that there is an issue and giving them enough time to exit the vehicle,” the automaker said in announcing the over-the-air update.

The cooling system is essential in keeping temperatures down during recharging, and operates automatically, with cars using Battery Management System software to make decisions about cooling cycles.

The software updates will tune the thermal management settings and charge settings in the two models, but Tesla did not provide details about just how the cooling system operation will be altered.

“We currently have well over half a million vehicles on the road, which is more than double the number that we had at the beginning of last year, and Tesla’s team of battery experts uses that data to thoroughly investigate incidents that occur and understand the root cause,” the automaker added. “Although fire incidents involving Tesla vehicles are already extremely rare and our cars are 10 times less likely to experience a fire than a gas car, we believe the right number of incidents to aspire to is zero.”

While the latest fires are under investigation, years ago, Tesla had to address a different root cause of several battery pack fires after several early Model S sedans suffered battery pack punctures after driving over various pieces of road debris. In response, Tesla tweaked the lowest permitted suspension settings to raise the vehicle’s ride height and also attached titanium underbody shields to existing cars to beef up battery pack protection.


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