Battery Type / Chemistry
A few readers might be viewing this incident report as confirming their fears of lithium batteries, but, if so, the authors would recommend that these readers consider what might happen to a lead-acid battery; particularly a sealed AGM battery, subjected to the same, sustained extreme overvoltage and current. The authors are reporting strictly within the scope of this particular aircraft, alternator, battery, and incident. They are not reporting a battery-type comparison under the same circumstances; including any comparison with lead-acid batteries or substantially different lithium battery chemistries such as those infamously used in laptops or smartphones.
The authors believe that the EarthX lithium-iron-phosphate battery behaves predictably and does okay in this incident relative to other battery types. This is particularly true considering the environment into which the EarthX battery was installed (no overvoltage protection, no warning light, no overboard vent), what happened in-flight, and what the battery was subjected to. The authors hope that their report leads to increased understanding of what is required to safely install and confidently fly EarthX (and other lithium-iron-phosphate) batteries as well as other battery types including lead-acid.