Calculations were carried out based on the Polish standard PN-W-89509:1997 Merchant ships, batteries, selection, in accordance with the following equation:
, where
P - power [W],
t - time [h],
Un - rated voltage[V],
a - temperature coefficient (curves are available in the standard) taking into account reduction of the capacity due to electrolyte temperature,
b - time coefficient (curves are available in the standard) taking into account reduction of the capacity in time.