Letter From America: Bike Shop Fire a Warning About e-Bike Battery Safety

Santa Fe, New Mexico

Mike Fritz is one of the best informed engineers in the US on the current state of e-bike batteries on the market.

So when a South Florida bike shop recently burned down after a refurbished e-bike battery exploded while undergoing a charge, I called Mike to get his take.

But a bit of history first. Fritz cut his teeth on lithium ion battery technology in the 1990s as vice president of product development at EV Global Motors, founded by the legendary Lee Iacocca. Iacocca is best known for leading the design and development of the now iconic 1964 Ford Mustang. He later launched EV Global in Southern California to make electric bikes, selling his first production model in 1999. It was Fritz who moved EV Global from 12-volt, sealed lead-acid batteries into the world of lithium ion power.

Fritz, now a consultant at Mike Fritz Associates, Inc., had been director of engineering at Schwinn for 17 years. And over the years he has compiled an extensive resume in the world of e-bike battery technology and is well versed on the pros and cons of lithium batteries. He is also the cofounder, partner and chief technology officer at Human Powered Solutions, Inc.

Fritz, who talked with the dealer whose store was gutted, said the refurbished battery was for a BagiBike, one of dozens of brands that have popped up in the US market. BagiBike is an Israeli company founded in 2010 and imports cruisers and folders through its US subsidiary in Miami, Florida. The company sells online, as well as through IBDs, and its bikes aren’t cheap. It’s entry level folder starts at US$2,400 (A$3,351) and its cruiser line launches at US$2,640 (A$3,574). Bafang hub motors, Shimano drivetrains and 48-volt lithium ion batteries — pretty standard stuff.

The dealer sent the original battery to a third-party refurbisher after learning a factory replacement was unavailable. When the refurbished battery came back, the dealer found it needed a charge, put it on a charger and left at 5.30pm. Forty-five minutes later, his store was engulfed in flames. A battery cell apparently exploded, fire officials said. (By the way, the owner lacked fire insurance, so take heed!)  From Fritz’s viewpoint, and he admits he’s a stickler, stay away from third-party refurbishers.

The issue of battery safety is one the industry, in general, likes to tap dance around when discussing safety with consumers. At random, I picked the owner’s manual from a 2021 Trek Intuvia, a modestly priced commuter using a Bosch battery and drivetrain. Let me boil down the safety warnings. Never use a high-pressure washer. Only use the Bosch charger that came with the bike. Once the bike is charged, unplug the charger from the bike and wall socket. And if the battery pack is damaged, take it to the dealer. If it needs replacement, use only a Bosch battery. There’s additional information on charging and storage if the bike is left unused. Pretty simple stuff.

But is it enough? I would argue no, and Fritz would mostly agree. But first, Fritz explained that when working with e-bike companies, especially start-ups, he’s clear on one point. Unless they spec battery cells made by Panasonic, LG or Samsung, he’s out.

“When someone retains me, I’m happy to work with them but I lay down the law – I’m in control of battery management,” he said. That’s pretty tough stuff.

Fritz points out that the risk of a battery fire linked to one of the industry’s top three suppliers is “miniscule” but not zero. And while Panasonic, LG and Samsung supply battery cells, other companies assemble them to fit various e-bike styles and configurations.

As an aside, battery cells used in e-bikes look like oversized AA batteries similar to batteries Tesla uses. Another type of lithium battery is the ‘pouch’ or prismatic battery, which many auto makers use and are found in laptops, cellphones and other electronic devices. There’s no hard case so they are lighter and easily shaped to fit inside a product.

So how much should consumers know about the batteries in their bikes? They should know a lot more than what’s found in most owner manuals.

Fritz said suppliers should tell dealers – and dealers should demand to know – what company made the battery cells found in bikes they sell.

Dealers also should demand to see the safety certificates issued to suppliers.

Depending on the calibre of bike being sold, relatively few components (think top-end fork) cost more than the battery. A battery pack alone – using cells from the big three – currently have an average OE price of between US$260 (A$359) and US$280 (A$384).

Shimano and Bosch sell systems— battery and motor. OE pricing ranges from US$800 (A$1,104) to US$1,200 (A$1,673), Fritz said.

As for price increases, OE pricing has remained relatively stable. But battery manufacturing is scaling up fast and that’s offsetting higher prices for raw materials, he added.        

At the moment, Fritz said he remains wary of Chinese battery suppliers, despite the flood of low-priced e-bikes hitting the US market.

“China is making progress. They have very talented engineers and over time they can compete (with the big three),” he said.

“Still, sub-par manufacturers in China are more interested in price and not safety,” he said. And it’s that mentality that causes problems. While Fritz maintains that dealers should know a lot more about battery sourcing on the bikes they sell, he’s less certain how much consumers need to know.

But consumers should be told in clear language never to charge a battery unattended.

At the moment, PeopleForBikes, a US advocacy group, is trying to hammer out wording for a core e-bike manual that all suppliers could use. It’s taking time as some 40 people from the industry, including Fritz, hash out content. It’s a tough assignment. Nobody wants to rain on a parade!


  1. Maurice on 29th April 2022 at 8:19 am

    Great article. But cannot help pointing out that LG Chem cells made in 2016 were used in batteries that caught fire in Australia and NZ in approx 2019, triggering a recall. LG Chem cells in Chevrolet Bolt electric cars resulting in a $2 billion recall and separately a recall of LG cells in residential solar battery storage (“power walls”)

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