We are going to be very general here as battery types and their use-cases are worthy of a whole article on their own. “Car batteries” as a whole refer to SLI batteries (starting, lighting, ignition) so they power the starter motor, the lights, and the ignition system. SLI batteries are usually lead-acid batteries and are made up of six galvanic cells, each producing 2.1 volts to make up a 12-volt battery. Heavy vehicles may have two batteries and use a 24-volt system, but 12-volt is standard for the majority of owners.

The cells in lead-acid batteries are made up of plates of lead and separate plates of lead dioxide, which are submerged into a an electrolyte solution of sulphuric acid and water to create a chemical reaction that produces electricity. Since this reaction takes place under the hood next to a very hot engine, the water in the solution will eventually evaporate. The electrolyte solution will condense and recycle itself inside batteries that are fully sealed, but low maintenance (or partially sealed) batteries can be topped up by the owner to keep them going strong. Let’s look at how you do it:

If you look at your battery and see that it is completely sealed with no holes and caps on the top surface, you are in possession of a no maintenance battery. This means that you do not need to do anything to keep the electrolyte solution in balance. Over the years it will eventually break down and wear out, holding less and and less of a charge until it needs to be replaced.

If you look at your battery and see caps and holes on the top surface, you are in possession of a low maintenance battery. Some will have a window where you can see the fluid level, if not, just open up a few of the port holes and take a look. Each cell should have the same amount of fluid, so top up any of the chambers that have gotten low. As the fluid is evaporating it is leaving the lead plates high and dry inside the battery, so you need to cover them with liquid so they can continue to function. On the west coast, regular tap water is fine, out east where tap water has a high mineral content you will need to use distilled water.

Your battery should last 3 to 5 years if not more, but depending on the quality of your battery, weather conditions, and other factors it may catch you off guard when it starts to lose charge. Here are some warning signs:

• Slow engine crank: If your engine slowly turns over a few times before ignition you may have a dwindling power supply.
• Check battery light: Warning lights associated with the battery will show on the dash where there is an issue. Click here to see what it looks like.
• Low fluid level: If your battery has a translucent fluid level window, take a look. If it is low, the usable life of the battery is diminishing.
• Bloated battery case: If the battery casing looks fat and distended like it just ate an Easter ham, it is a sign of excessive heat that is causing the case to swell and fail.
• Rotten egg smell: This means sulfer which means a battery leak. Get it checked immediately.
• Third birthday party: After 3 it is getting old, start having it tested at each oil change to make sure it is functioning properly.