What is the lifespan of a car battery?
The battery on your car has to work hard, and that means dealing with all kinds of loads in all sorts of conditions. Over time, the effectiveness of a battery will be compromised. But how long will it be before your battery is of no use and you need to replace it, and what will the signs be?
The general rule of thumb is that a battery should last around three years. This is in the case of a battery in a car you drive every day, through all seasons. In a car you use less often and keep indoors, say a classic car or something similar, you can stretch this out to around five years.
There is nothing you can really do to stop a battery from running out of life. While you may look at it as nothing more than a big block, the reality is that there are all kinds of chemical reactions going on inside your battery, and over time the chemicals at play lose their effectiveness.
How can I tell when my car battery needs replacing?
The first sign that the battery is dying is when the car becomes harder to start. When a car is running, it’s the alternator’s job to pump electricity through the car. However, it needs to be brought to life with the battery. If the battery is starting to fail, your car will be come slow and sluggish to start, and that’s if it even starts at all.
Batteries also perform differently depending on the temperature. Your old battery might be fine through the summer, because the ambient temperature is higher, so the battery has better conditions to work in. Come that first cold snap, the battery can fail, because it won’t have the power to overcome the cold.
The other giveaway is that things stop working when the engine isn’t running. The windows might become slow, the stereo might lose it stored settings, the lights might not work… all signs the battery has had it.
How do I perform a car battery health check?
The first visual check comes in the form of the 'bubble'. On top of some batteries, there will be a small (less than a centimetre in diameter) ‘window’. Look directly down this. In a healthy battery you should see green. In a flat battery you’ll see black or red.
The other way is to put a multi-meter on it. Set the meter to 20v and put the red probe on the positive terminal and the black probe on the negative terminal. The reading should be 12.6v or higher. Anything less, and the battery isn’t in good health. You can try charging it with a trickle charger, then leave it a few days and test it again. If the reading is still low, it’s definitely time for a new battery.
Your Haynes manual will give you the specification you need for your car. Don’t buy any old battery that fits, you need the right one, with the right power and the right specs.