'Hanging by a thread': Leaked emails tell the story of a design flaw discovered in 2012 in Tesla's Model S battery that could lead to breakdowns and fires

Tesla Model S Elon Musk
Flickr / Maurizio Pesce
Leaked emails from 2012 show that Tesla knew the Model S battery had a design flaw that could lead to breakdowns and fires, but still sold the cars. It is unclear when the design flaw was fixed.
This discovery comes from the fact that Tesla is handling customer complaints about manufacturing defects in its new Model Y crossover vehicles, including loose seat belts and rear seats.
The National Highway Transportation Safety Administration has just initiated an investigation of faulty Tesla Model S touchscreens from 2012 to 2015. The investigation includes 63,000 vehicles.
Tesla did not respond to Business Insider's request for comment.
If you work at Tesla or own a Tesla and would like to speak confidentially about your experience, send an email to llopez@businessinsider.com
Read Business Insider's full investigation into Tesla Model S battery design issues.
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When Tesla's first car, the Model S, rolled out of the Fremont, California facility, emails showed that the company was still struggling with a design flaw that could result in battery leakage.
These leaks could then lead to the car's battery being short-circuited or leaving flammable residues in the battery, according to experts with whom BI spoke for this investigation.
Related Video: The Science Behind Tesla's Million-Mile Battery
The problem was a poorly designed cooling mechanism - internally called a coil or bandolier - that wraps around the battery and pushes coolant around it to regulate the temperature. According to internal emails and three people familiar with the matter, the end of the cooling coil was made of weak aluminum, and sometimes tiny pinholes formed in which the male and female parts of the end were to be soldered together.
The part has been tested twice by third parties. First, in July 2012, some cooling coils were sent to a test lab called IMR Test Labs in New York State. According to the IMR report, which was examined by Business Insider, the ends of the cooling coils did not meet the chemical requirements for an aluminum alloy with adjustable strength. A source close to the matter said the results were shared with Tesla, but the S models continued to roll out of the factory. According to Tesla's third quarter 2012 earnings report, the company delivered more than 250 S. sedans.
Jason Schug, Vice President at Ricardo Strategic Consulting, demolished Tesla's S and X models, which have the same battery. He told Business Insider that coolant that gets into a battery module could make the battery unusable.
"When we disassembled the Tesla Model X, a technician accidentally spilled coolant into the battery and it sat there for a long time," Schug told Business Insider. "There was no immediate danger, but when we removed the battery modules some time later, we noticed severe corrosion on the battery cells and it was bad enough that some of the cells were leaking electrolyte. If this should happen in the field and go unnoticed, this could lead to the battery being bricked up. "
"Bricking the Battery" means that the battery is empty.
If you work at Tesla and want to share your experience or own a Tesla and want to talk about it, send an email to llopez@businessinsider.com.
Find the problem now and fix it later
The part was tested again in August 2012. Tesla sent the part to Exponent, an engineering firm for engineering and science. According to internal emails reviewed by Business Insider, Tesla was concerned that the end connections on the cooling coils simply did not stay together and as such were a source of leakage. A Tesla employee described it in August 2012, according to internal emails from Business Insider, as "hanging on a thread".
The engineer who did this at Exponent was a man named Scott Lieberman. He is now at LPI Inc. Lieberman declined to speak to Business Insider about this story. However, in internal emails between him and Tesla viewed by Business Insider, his opinion on this part was clear. After limited tests, he found defects - especially tiny pinholes that could lead to leaks - in the materials tested.
According to documents checked by Business Insider, Tesla continued to find leaking coils in various production phases until the end of 2012. Some were found on the production line late enough to be called a "critical quality problem" or liquid was found to have got into the battery, as internal emails from Business 2012 showed, reported by Business Insider. At this point in time, the problem had been reported to management, as evidenced by documents.
In another email sent in late September 2012, employees said that production line employees sometimes needed to use a hammer to hold the end pieces together. According to emails, Tesla continued to find leaking coils in the production line until November 2012, and management was eventually informed of the problem. However, it is unclear when the company changed the design of the part. Tesla did not respond to Business Insider's request for comment.
A former employee who left the company in 2014 said employees sometimes forced the end fittings together when Tesla hurried to meet production targets.
"We found [leaks] in some vehicles," said the former employee. "I don't know exactly how many there are, but that's exactly what I would consider normal for a company that chooses to start with a limited amount of R&D in the hope: 'We will start with it and do inspections Place for us to catch it at the facility. '"
Read BI's full investigation into the battery design issues of the S.
If you work at Tesla and would like to share your experience or own a Tesla and want to talk about it, send an email to llopez@businessinsider.com.
Mark Matousek also contributed to the coverage of this story.
Read the original article about Business Insider

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