Zig unit
Zig unit, Zig, charger distribution unit, power distribution unit, Sargent, BCA, caravan charger unit
A Zig unit is the British charger-and-distribution box in caravans and motorhomes: it charges the leisure battery from 230 V mains and distributes 12 V to the circuits through fuses. The brand name became the generic term for the whole class.
A typical unit combines charger, 12 V busbar, fuses and a state-of-charge gauge — the job now done by a control panel together with a Sargent EC or BCA unit. Older Zig units charge at a simple unregulated voltage and are unsuitable for LiFePO4: the battery never fully charges and the BMS may disconnect. Converting to lithium normally means replacing the unit with a multi-stage charger or a Victron inverter-charger.