Charging a battery

Part 1. Preparation and safety

Objective

• Correctly charge a battery using battery charging equipment.

Personal safety

Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

• Work clothing - such as coveralls and steel-capped footwear
• Eye protection - such as safety glasses and face masks
• Ear protection - such as earmuffs and earplugs
• Hand protection - such as rubber gloves and barrier cream
• Respiratory equipment - such as face masks and valved respirators

If you are not certain what is appropriate or required, ask your supervisor.

Safety check

• Make all connections between the battery charger and the battery to be charged before connecting to the power supply or turning “ON” any switches.
• Never try to charge a 'frozen' battery.
• Make sure that the voltage used to charge the system never exceeds the system design while charging. For instance if you connect two 12 volt batteries in 'series' for charging you should use the 24 volt setting on the charger, however if you connect the same two batteries in 'parallel' you should only use the 12 volt setting on the charger.
• Never allow a spark or flame to get near the battery.
• Always use the markings on the battery to determine the positive and negative terminals. Never simply use the colour of the cables to determine the positive or negative terminals.
• Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.

Points to note

• Slow charging a battery is less stressful on a battery than fast charging is.
• Always remove the negative battery terminal while changing a battery to reduce risk to the vehicle, especially with today’s electronically intensive cars. Use a 'memory minder' to retain electronic settings.
• After charging the battery and reinstalling it, always clean the battery terminals and posts.

Part 2: Step-by-step instruction

1. Inspect the battery
   Carry out a visual inspection of the battery to ensure there are no cracks or holes in the casing.
2. Connect the charger
   Check the charger is unplugged from the wall and turned off. Connect the red lead from the charger to the positive battery terminal. Connect the black lead from the charger to the negative battery terminal. Turn the charger on. Check the charger amperage output to ensure the battery is charging correctly. A slow charger usually charges at a rate of less than 5 amperes. A fast charger charges at a much higher ampere rate depending on the original battery state of charge and should only be carried out under constant supervision.
3. Disconnect the charger
   Once the battery is charged turn the charger off. Disconnect the black lead from the negative battery terminal, and the red lead from the positive battery terminal.
4. Test the battery
   Allow the battery to stand for at least 5 minutes before testing the battery. Using a load tester or hydrometer, test the charged state of the battery.