sand battery

English

Noun

sand battery (plural sand batteries)

1. (electronics, historical) An unspillable electrochemical battery whose cells use electrolyte soaked sand – typically used to test telegraph cables at sea.
2. (military, historical) A sand fort equipped with an artillery battery, frequently found in coastal defense, usually having organic infantry attached.
3. (thermodynamics, industrial planning) A thermal storage battery which uses sand as the storage medium.