It's probably more complex than this, but, just a thought or two. If the ELT uses a Lithium Magnesium battery, I hope the Magnesium isn't in the same form as was used in "Mag" wheels! Hard to control fires from car wrecks was the reason "Mag" wheels aren't made of Magnesium any longer, but instead are made of Aluminum. . Maybe this type of battery should only be small, for use in low capacity situations, like in smoke detectors, watches, and cameras, so the stored energy isn't enough to burn through routine precautions. I'm sure an alert beacon transmitter would use a lot of current, if it's to transmit for very long, so it probably has a pretty high capacity battery. I've brushed up on my knowledge of different Lithium battery technologies, and it seems like using high capacity ones and/or storing them in close proximity to each other, may be a no no, across the board, until better practices in quality control, design, and use are practiced!