Which charger voltage and current settings suit a 12V 100Ah LiFePO4 battery?

Direct answer: For the Redway 12V 100Ah page the published charge ceiling is 14.6V, a typical charger entry is 14.6V at 20A (about 5 hours), and the maximum continuous charge current is 50A (0.5C) or 100A (1C). Use a lithium (CC/CV) profile at or below those values, switch off equalisation and desulphation modes, and verify the output with a meter. Check your exact model, because other 100Ah pages differ.

The numbers on the 12V 100Ah page: nominal 12.8V, max charge voltage 14.6V, charger “14.6V 20A (0.2C), 5 hours full charge”, maximum continuous charge current 50A (0.5C) or 100A (1C), standard continuous charge current 25A or 50A, discharge cut-off 10V, and a charge temperature of 0 to 60 °C. Our arithmetic, not stated on the page: 14.6V is 3.65V per cell across four cells.

What the figures mean in practice: 14.6V is the ceiling, not a target for every stage, so a charger set higher is outside the page’s stated limit. A current of 20A is about 0.2C, which is gentle and fills the battery in roughly 100Ah ÷ 20A = 5 hours. Higher currents are allowed up to the limits listed, if the charger, cables and the battery’s temperature allow.

Settings to check on the charger: choose a lithium or LiFePO4 profile, or set the voltage manually to the value above; turn off equalisation and desulphation modes designed for lead-acid; turn off temperature compensation if the charger adjusts voltage by temperature; and set the current limit to a value you have chosen at or below the page limit. The float behaviour is not published, so ask Redway what to use.

Other 100Ah pages differ, so do not copy numbers between models. The 12V 100Ah EU page lists 14.6V maximum charge and a 100A maximum continuous charge current. The 12V 100Ah Ultra page has its own table, which lists only “Charger: Yes” in that field and more than 5,000 cycles at 80% DOD. Confirm which model you have from its label.

Verify the output before connecting: measure the charger’s voltage with a meter, and measure again at the battery terminals during charging to see the voltage drop in the cable. Charging below 0 °C is outside the stated range, so see our post on cold-weather charging for a 12V LiFePO4 battery. If the battery will not accept charge, check the BMS protection state rather than raising the voltage.