A liquid reserve battery including: a collapsible storage unit having a liquid electrolyte stored therein; a battery cell having an inlet in communication with an outlet of the collapsible storage unit, the battery cell having gaps dispersed therein; a first pyrotechnic material disposed adjacent the collapsible storage unit such that initiation of the first pyrotechnic material provides pressure to collapse the collapsible storage unit to heat and force the liquid electrolyte through the outlet and into the gaps; and one or more heat exchangers disposed between the outlet of the collapsible storage unit and the inlet of the battery cell.