"EXPLOSION ROCKS RIO DELL" - Battery storage in Conex box

[GoldDigger]

One mode of failure in some lithium cells that are kept constantly at it near 100% charge is the formation of lithium metal dendrites extending from the lithium electrode. These can pierce the separator between electrodes and short out the cell.

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[jaggedben]

Mystery solved, and no surprise to me, it was lead acid. (You guys casting aspersions on LiFePO can stop, and especially with the false associations with lithium NMC chemistry in the cars and bus).

Local TV station posted a new shot, and it's zoomable.

Battery storage container explodes, rocking Rio Dell RV park

The River's Edge RV park was shaken Wednesday afternoon when a battery storage container exploded.

krcrtv.com

In my attached snapshot you can make out it says 'Valve Regulated Lead Acid Battery' and also the units strongly resemble these.

From the fact they had an explosion but no subsequent engulfing fire one could almost rule out lithium thermal runaway in favor of a hydrogen explosion from poor lead acid ventilation.

 

[GoldDigger]

VRLA batteries can be either AGM or Gel construction, with the AGM generally capable of higher charge rates. Neither one will vent hydrogen uness the charge control system has failed. In normal operation the hydrogen and oxygen pressure inside each cell will be kept below the valve release pressure by controlled recombination.
It is still advisable to provide ventilation capable of handling a possible charging system failure. But a faulty installation that blocked normal ventilation would not cause any noticeable problems until the failure occurred.