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Posted on Oct 19, 2022 in Automotive Electronics

Causes Of Fast Car Battery Drain

Causes Of Fast Car Battery Drain

We’ve all been there. You’re driving along, and suddenly your car’s battery dies. Or maybe you start your car, and the battery is already dead. Either way, it’s frustrating and can leave you stranded. But why my car battery is draining fast? Here are some of the most common reasons for fast battery drains.

The leading causes of rapid battery drain

Generator malfunctions

If the alternator doesn’t provide enough power, the battery will run out of power quickly after the car has stopped. You need to use a multimeter to check the generator relay to find out what’s wrong. After starting all the standard equipment and devices, the voltage in the electrical system should be around 13-14 volts. If it’s less than that, it means insufficient power is being supplied – meaning that there’s something wrong with the generator.

Even a new battery will not work well in the network when the generator is not running. The battery will become unusable from increased loads without having served its due date. Therefore, it is necessary to seek help from the nearest car service.

Low temperature

Winter is the most difficult time for car batteries. The electrolyte in the cold becomes thicker, making it harder for the battery to hold a charge. In winter, you should regularly check the electrolyte level and its charge. You can track the average level of electrolytes by using a table available online for free. One important rule to remember when driving in the winter is never to let the battery run out of power. It’s a good idea to move the battery to a warm place, if possible, and bring the power source home with you.

causes of rapid battery drain

Short circuit in the battery

If a battery’s positive and negative electrodes meet, it can cause a short circuit. It is often because of lead or sludge buildup at the bottom of the battery. Unfortunately, it can be hard to figure out what caused the short circuit, and in most cases, the battery will need to be replaced.


If a battery is charged too often or too long, it can overheat and cause a fire. Overcharging also causes the battery to wear out faster and reduces its lifespan. To avoid this, you should only charge the battery when it’s below 50% and never leave it plugged in for more than 24 hours.

Defective battery

A defective battery is one of the most common reasons for fast battery drains. If you suspect that your battery is defective, you should take it to a professional to have it tested. A defective battery will usually need to be replaced.

You didn’t turn off the car correctly

A common reason your car loses charge quickly is that you forgot to turn it off properly. For example, you left the headlights or the interior light on, or the boot or your door isn’t shut all the way. Some cars automatically shut the lights off if they’ve been on for too long or send a warning beep, but many cars still require manual effort. If your car’s not being fully turned off regularly, the battery might wear out faster because of the constant drain. Check doors and lights before leaving the car to ensure everything is switched off and locked up properly.

Parasitic drain

A parasitic drain is when your car’s battery continues to lose power even after the car is parked. This drainage happens much more than usual, and a faulty accessory usually causes it in the car. For example, a sensor or interior light that does not turn off automatically will keep consuming power until it is manually turned off. If you think your car has a parasitic drain, a mechanic can quickly diagnose this by performing a parasitic current draw test. It will involve checking for any electrical components draining power from the battery, even when the car is turned off.

Ways to avoid draining your car battery

Find out the age of your car battery

Most cars require 12-volt batteries that last three to five years. Therefore, you must know the age of the battery to replace it before it fails.

Check symptoms of a dying battery

When you turn the key to start your car, the engine doesn’t start immediately. It might mean that your battery is getting weak and will die soon. Another sign that your battery might be weak is if the headlights are dim when you turn them on, even when the engine isn’t running.

Ways to avoid draining car battery

Keep driving

You should drive your car every few days so the alternator can do its job and keep the battery from dying. Driving regularly also keeps the engine lubricated and makes the tires wear evenly.

If you make a lot of short trips, your car’s battery will get tired. To avoid this, try to use your car for more time once you’re on the road. You can also buy an external battery charger to keep your car’s battery healthy if you can’t use it often or for long trips.

Keep your car in a garage

You should try and keep your car in a garage – this helps in protecting the battery from extreme weather.

If you don’t have a garage, park your car in the shade. You can also consider investing in a battery blanket to prevent car fluids from freezing in winter.

Turn off your car’s accessories

Turn them off when you’re not using your car’s accessories, like the radio or the air conditioner. These accessories strain the battery and can cause it to drain quickly.

Check the electrolyte level

The electrolyte level in a lead-acid battery should be between 1.265 and 1.280. You should add distilled water to the battery if it’s below this. If the level is above this, you should take the battery to a professional to have it serviced.

Clean the terminals

If you notice that your car’s battery is losing charge quickly, one of the first things you should do is clean the terminals. To do this:

  • Turn off the car and remove the battery’s negative terminal.
  • Clean the terminal with a wire brush and some distilled water.
  • Dry the terminal with a cloth and put the terminal back on.
  • Do the same thing with the positive terminal.