Your car’s battery is a key part, and it’s important to understand how it works and how to maintain it. Battery maintenance is often overlooked, as many of us find it easy to take our battery for granted. It’s frequently only when our battery fails that we remember how crucial it is to our vehicle. In this post we’ll be taking an in depth look at batteries, focussing on how to maintain, charge, and replace them.

Basic Battery Maintenance

Maintaining your battery properly can significantly increase its lifespan, and will definitely help you avoid the nightmare of your car failing to start on a cold morning. There are key maintenance checks to carry out regularly, battery load tests and acid level checks. It’s also important to use your vehicle regularly, as left unused your battery will drain. You should aim to use your car at least every three days, or check your battery before use if the vehicle has been left unused for some time.

a mechanic is testing a car battery

Battery Load Tests

A battery load test can detect the need for the battery to be recharged, or replaced, and pick up problems with your alternator’s ability to recharge the battery. A battery load test can be carried out by a mechanic, or you can carry one out yourself with the right equipment.

  1. To test the charge of the battery, you should connect a multi-meter to the battery. The probes on the multi-meter will be color-coded for positive (+) and negative (-) connections. Connect the red probe to the positive terminal and the black probe to the negative terminal. Check the reading on the multi-meter for around 12.6 volts. If it reads less than that, the battery is insufficiently charged, and you should recharge it.
  2. If the battery is sufficiently charged you should then test its performance under load. While the multi-meter remains connected, ask a friend to start the vehicle. It’s of the utmost important to ensure that the vehicle is in neutral when its started, and that the handbrake is engaged. You should also ensure that the leads from the multi-meter are free from any moving engine parts. As the car starts, watch the meter reading to see if the voltage produced by the battery drops below 10 volts. If the voltage drops below 10 volts it indicates that you might need to replace your battery.
  3. The load from the starter motor will be taken over by the charging effect of the alternator. The voltage reading should start to increase after a few seconds of the engine running, and after 15 to 20 seconds the reading should be higher than the original 12.6 volts. If it isn’t, it suggests that the alternator is failing to charge the battery. You should get your alternator checked by a mechanic and consider replacing your battery if it is around 4 years old.

Battery Acid Level Tests

You should check the battery acid levels 2 or 3 times a year, checking more frequently as the battery ages. 

  1. To do this you must first safely remove the battery, and you should take this opportunity to clean up the top of the battery. We’ll cover this later on, but its also a key step in this process.
  2. Having done that, the first step is to check the electrolyte levels. First remove the plastic covers over the cell ports. Once the covers are open, you should remove any dirt that has built up underneath. With the cells open, check if the plates are exposed or coming close to exposure. Also check if the electrolyte levels are not equal in each cell.
  3. If the electrolyte levels need topping up, you should add DISTILLED WATER. No other form of water is acceptable, and certainly not acid of any description. You should only add enough to cover the electrodes or plates.
  4. Once you have topped up the battery you should replace the covers, refit the battery, and then test it by starting the car and driving around a little. If there has been no improvement in how the battery is performing, it’s possible that you will need to replace the battery.

How to Remove and Clean a Battery

a mechanic is taking out the car battery from a car.

If you need to charge your battery, or check the battery acid levels, you will first need to remove the battery safely and clean the terminals.

  1. Locate the battery and then find the negative terminal. The negative terminal should be marked by a (-) symbol, while a (+) sign will mark the positive terminal. The negative terminal should also be black and have a black plastic cap, while the positive terminal should be red and have a red plastic cap. 
  2. Loosen the nut on the negative terminal with an appropriately sized wrench, remove the negative connector cable from the battery and push it far aside. It’s essential to make sure this cable is entirely out of the way and doesn’t come in contact with the battery again until you are ready.
  3. After removing the negative connector, repeat the exact same process for the positive connector. Again, ensure that you push the cable far away and out of contact with the battery.
  4. It is likely that your battery will have a clamp securing it into its tray. Using a wrench to loosen the securing nuts, remove the clamp and then you will be able to remove the battery. Expect the battery to be heavy as most weigh between 30-50 pounds.
  5. You can clean the terminals with either a proprietary cleaning product or with baking soda and water. Either way you should use gloves while cleaning the terminals, brush off any corrosion with a wire brush, and clean and dry the area with a paper towel.

How to Charge a Battery

You can charge your battery at home as long as you have an appropriate charger for the battery type in your vehicle. When charging your battery, it is important not to overcharge the battery, so you should check on the progress of the charge regularly. Properly maintained, and kept at a good level of charge, a battery should last at least 4 years.