[SystemSafety] E-bike battery fires in NY

[M Ellims]

For some perspective - it's not just batteries...

In 2010–2014, U.S. municipal fire departments responded to an estimated 15,970 home fires involving clothes dryers or washing machines each year.* These fires resulted in annual losses estimated at:  
- 13 civilian deaths 
- 440 civilian injuries 
- and $238 million in direct property damage

>From https://www.integratedfiresystems.com/washing-machine-and-dryer-fires/#:~:text=NFPA%20reports%20that%20US%20fire,%24238%20million%20in%20property%20damage.

However the risk of a single cell failing can simply be mitigated in many cases, research from NASA and NREL suggests that by simply separating cells from each other by 1-2mm almost removes the risk of a chain reaction occurring. Current practice for low cost devices e.g. kick-scoters, where cells are simply bound next to each other using tape.

It would also probably be better if lithium iron phosphate chemistries were used rather than say - nickel-magnesium-cobalt (LFP vs NMC) as they are much less liable to fail catastrophically, the down side is that they are less energy dense.

And before someone mentions electric vehicles, petrol vehicles are actually really quite bad... hybrids seem worse though
https://www.kbb.com/car-news/study-electric-vehicles-involved-in-fewest-car-fires/



-----Original Message-----
From: systemsafety [mailto:systemsafety-bounces at lists.techfak.uni-bielefeld.de] On Behalf Of Peter Bernard Ladkin
Sent: 15 November 2022 08:45
To: The System Safety List
Subject: [SystemSafety] E-bike battery fires in NY


In NYC there have been about two hundred building fires and 6 deaths this year due to e-bike batteries catching fire https://www.theguardian.com/us-news/2022/nov/14/new-york-e-bike-batteries-fires-delivery-workers

The issue, as we know, is that lithium-ion batteries are not particularly safe, and are prone to "thermal runaway" as it is called, . Safety has to be designed and manufactured in, and manufacturing quality control has to be very good (recall the Boeing 787 had trouble with its batteries, causing some fires, and the NTSB was scathing about the quality control at its manufacturer - and that is aerospace!).
And sometimes it isn't.

The article talks about measures such as only having batteries certified by UL in circulation. That seems to be impractical for people who work in low-income city-delivery jobs. But that seems to be a matter of regulatory choice -- maybe the city resources devoted to extinguishing those two hundred fires could be better targeted at battery certification and control?

There are three reasons for the relative unsafety of lithium-ion batteries. Two concern ignition and fire. One is the relatively low temperature at which lithium spontaneously combusts, which can be attained in spikes in the electrodes when charging or damaged; the other is the presence of gases, within the battery, which burn. The two phenomena lead to a process called "thermal runaway". The third is that lithium-battery fires are hard to extinguish.

A decade ago, I chaired the DKE committee (German electrotechical standards organisation) looking at the risk analysis of charging electric road vehicles (cars and trucks, not low-voltag systems such as bikes). The auto industry went to some lengths to try to cancel the working group and eventually succeeded.

Causalis also worked on the case of one particularly expensive lithium-battery fire.

PBL

Prof. i.R. Dr. Peter Bernard Ladkin, Bielefeld, Germany
Tel+msg +49 (0)521 880 7319  www.rvs-bi.de