How to charge a car battery

Instructions on charging a battery safely

• Fully recharge the battery as soon as possible following each discharge
• Always check that battery charger is suitable for the battery
• Never use a battery charger without automatic shutoff
• An electronic voltage-controlled battery charger, preferably based on an IUoU charge profile, is recommended
• Charging to avoid acid stratification (not needed for AGM)
• Use a charger with IU characteristics and higher charging voltage (2.6 V/cell)
• This overcharge should only be used for a short time period to avoid water loss
• The open-circuit voltage after charge should be 2.12 - 2.13 V/cell
• For every 0/1 V difference to 12.7 / 12.8 V, the battery should be charged for 1 hour
• Never charge frozen batteries or batteries with a temperature above 45˚
• Connect the positive battery terminal (+) with the positive charger terminal, and the negative battery terminal with the negative charger terminal
• Do not turn on the charger until the battery has been fully connected
• When charging is complete, first turn off the charger
• Stop charging if the battery becomes hot or acid escapes!
• When charging, ensure good ventilation

Test a battery

The best and easiest way to test a battery is using a voltmeter or multimeter to measure the voltage. Once you know the exact voltage, use the table below to gauge the state of charge.

Make sure the battery is charged

To ensure that the battery can supply its stated starting power, it first needs to be fully charged. The recommended charging current is 10% of nominal capacity in amperes (e.g. a 4 Ah battery requires a 0.4A [Ampere] charging current). We recommend that you ensure your battery is fully charged before fitment to ensure a long service life.

• A new battery after activation is approximately 80% charged.
• Initial charging is always recommended. Never quick charge.
• You can find a detailed description of how to charge the battery in the instruction manual supplied with your battery.