Apple Inc (AAPL)

[boston745]

Cell phone charging between couch cushions sparks house fire

A charging cell phone that was “tucked into the cushions” of a couch sparked a house fire in Pennsylvania early Wednesday morning, according to fire officials.

The Adams Area Fire District said firefighters arrived and found the fire “isolated” to a couch in a bedroom. The fire was quickly extinguished.

Fire officials said the fire was caused by a charging cell phone wedged into the couch cushions and a blanket.

Its doubtful the phone was tucked and likely instead fell in between cushions. However phone batteries seldom get hot enough to cause spontaneous combustion like this. Its more likely the phones battery was already malfunctioning due overcharge of battery cells from EM radiation. Dendrite buildup another possibility.

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How does EMF cause lithium batteries to experience thermal runaway and thus spontaneously combust? One of two main ways:

#1 - Overcharge/Discharge

With various impressed external magnetic field intensities an effect was noticed on the charge and discharge curves as well as the charge and mass concentrations within the batteries. With the two-dimensional model starting from 0mT and going to 1mT had the effect of discharging the battery faster and charging the battery faster. With the two-dimensional model starting from 1mT and going to -1mT had the effect of charging the battery faster. In either case an effect on the various characteristics of the battery were studied. With the experiments conducted on the two types of batteries the effect was more profound than subtle. Discharge times were twice as fast and charge times were equally
affected. With the smaller batteries they all generally charged faster under the presence of a magnetic field due to more uniform penetration. In the presence of the field they also discharged faster. The larger batteries would not see the same uniform penetration because only a small area of the battery sees the center of the coil it is placed on

In this dissertation, they found that external magnetic fields significantly increased charge and discharge rates in individual lithium battery cells; like shown in the following image. They also found that smaller batteries were impacted to a greater degree than larger ones. This is likely a reason Tesla is switching to larger battery cells in addition to employing magnetic attenuating honeycomb sandwich battery pack.

Thermal Runaway of Lithium-Ion Batteries Triggered by Electromagnetic Interference
https://ieeexplore.ieee.org/document/9025761

https://ars.els-cdn.com/content/image/1-s2.0-S0378775320302172-fx1_lrg.jpg

#2 - Stimulation of Dendrite Growth

Thermoelectric current causes asymmetric growth pattern of dendrites.

thermoelectromagnetic convection occurs in the vicinity of the solid-liquid interface, and vortices are generated between dendritic arms. It is shown that the thermoelectromagnetic convection has a major influence on dendritic morphology.

Quote Sources:

#1:https://digitalcommons.njit.edu/theses/1743

#2:https://www.sciencedirect.com/science/article/abs/pii/S001793101930225X