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Kate on Cars - Oct 2013 ~ What does a battery really do?

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Kate on Cars - Oct 2013
What does a battery really do?

by Kate Jonasse

The battery in your car stores electricity, the majority of which is required to start the engine. Most light-duty passenger cars need between 200 and 600 amps to make the starter turn the engine over. The battery also provides electricity for accessories (like the radio) when the engine is off. Once your car starts, the alternator takes over for the battery supplying the electricity your car needs to operate. At that point, the battery acts as a voltage stabilizer, and catches voltage spikes that the alternator may throw out. When the engine is running, the battery charging system generally stays at around 13.5 volts

It takes electricity to run nearly everything on your car – the starter, the computer, the fuel-injectors, the spark to fire the spark plugs, the heater, all the sensors, and much more. Without electricity, your vehicle wouldn’t start or run.

What kinds of batteries are there and what kind should I put in my car?

The two most popular types of automotive battery are the standard lead-acid type battery, and the AGM (absorbed glass mat) battery.

A super-quick run-down on the differences between standard lead-acid batteries and AGM batteries is that standard lead-acid batteries have a loose liquid electrolyte inside of them, and AGM batteries have fiber-glass that acts like a sponge to hold the electrolyte. AGM batteries provide more power per size than standard lead-acid batteries, last longer and are more shock resistant. AGM’s are also more expensive. More cars are being equipped with the better quality AGM’s each year.

You should put a battery of the proper size, shape and load rating in your car. Battery manufacturers have a guide where you can look up your vehicle, then check the type and rating of battery that it should be equipped with. An AGM battery can be installed on a vehicle originally equipped with a standard lead-acid battery, but the battery size and rating may need to be changed. Don’t just swap a standard battery for an AGM without doing some research first. That could cause damage to the electrical components on the car. Always make sure to install the correct battery for your car. If you’re not sure whether a battery is right or not, ask your trusted technician.

Battery Failures

Have your repair shop test your battery periodically (at least twice a year) to monitor it’s health. It is possible for a battery to test perfectly good one day, yet fail to start the car the next. This can happen when the plates inside the battery short out – it’s a quick death that cannot always be predicted. So please don’t get mad at your repair shop for missing this type of thing – this type of failure is not something that can be tested for or necessarily predicted.

Usually, batteries slowly over time lose their ability to provide voltage for starting the engine. This happens when the plates inside the battery get sulfated (coated) and electricity cannot flow as well. If you notice that the engine cranks slower than it used to, have your repair shop test the system right away before you get stranded.

What kind of maintenance does my battery need?

Most modern day batteries need little to no maintenance. Occasionally, a battery service may be in order. If your battery is leaking acid or the terminals are corroded (the green fuzzy stuff), then testing and service is needed.

A battery service entails spraying a special cleaner on the battery to deactivate and remove the acid, removing the corrosion from the cables and terminals, and if there are serviceable caps on top of the battery then checking and correcting the electrolyte level inside the battery.

If the battery is leaking acid, then system tests should be performed to determine why. It’s possible that the battery may be leaking due to the alternator overcharging it, which in turn can be caused by a faulty alternator, incorrect battery type or rating being installed, computer miscalculation, or some other issue. The point is, testing should be performed when a battery service is needed to find out why.

Batteries are a great topic that I can cover more on in a future article. If you need help with or have questions about your vehicle, email me.