eScooters Recalled Due to Battery Fire Risk: Expert Witness Analysis on Experts.com

Rechargeable Lithium-Ion batteries have been the root cause of overheating and fires in a number of different types of consumer products.  Some examples include cell phones, hoverboards (self-balancing skateboards), battery shipments, etc.  Most recently, eScooters used as rentals in many cities have had similar battery problems and some fires have resulted.  I was asked to provide some comments from the perspective of a Mechanical Engineeering Expert as part of a blog post written by Nick Rishwain of Experts.com.

Nick asked for my input on several technical questions related to Li-Ion battery technology, damage, failure, and potential for fires.

From the Blog post at Experts.com :

With regard to Lithium-Ion batteries, there are several failure modes that can ultimately lead to smoke or fire.

External damage is one mechanism that can lead to failure and smoke or fire. By breaching the external battery package, the reactive internal contents will be exposed to air and moisture.

The failure modes generally involve heat and overheating of the battery in some way.

Some of the heating mechanisms are:

  • External Short Circuit
  • Internal Short Circuit
  • Overcharge
  • Overdischarge
  • External Heating
  • Overheating (self-heating)

Each of these heating mechanisms may ultimately result in battery temperature becoming too high.

The elevated temperature leads to gas generation and additional generation of heat internal to the battery.

If this heat generation exceeds the ability to dissipate the heat, a thermal runaway may occur.

If a thermal runaway occurs, then it may be followed by

  • venting,
  • rupture of the battery container, and then potential
  • fire and explosion.