What Do You Do When Your Battery Light Comes On?

Car battery with jumper cables connected

What is a car battery?

The battery is essential to a car’s functioning. There are many aspects and components of a car that are affected by a car battery. It is essential in maintaining the battery and getting the right car battery replacement when needed. While it is common for car batteries to quit in the winter, it is the summer that sees more needs for car battery replacement – that is surprising for most people. 

Why does car battery die when not in use?

From starting your car to keeping it running, the battery is an essential key part of your car. The clock, radio, security system, and computer all continue to draw power from a car battery even when the car isn’t running. This is a parasitic drain, aka key-off battery drain, and will drain a battery dead even with a car not being driven for weeks. 

While the alternator’s job is to keep the battery charged under normal conditions, when a car just sits idle for an extended amount of time, it can damage the battery. How long your car can sit unused without killing the battery will depend on how healthy and how old the battery is. On average, a battery that is three years old or older that sits for a month or more will need a car battery replacement. 

The following tips will help you maximize the performance of your car battery and keep your car running. 

  1. Lights​​​.

Leaving the dome light, headlights, or the interior lights on will drain a battery quickly. When this is done too many times, a car battery replacement is needed.

  1. Condition.

A battery ha is poorly maintained will weaken it to the point it can’t hold a charge for long. Even the memory function of the radio can drain a weak battery.

  1. Connections.

Corroded or loose battery connections prevent a battery from charging while you’re driving. So when you park your car, the electronic components that continue to drain the battery are pulling off what charge is left in the battery. Cleaning the connections and tightening any loose connections could save you from having to purchase a car battery replacement.

  1. Parasitic Drains.

There are parasitic drains that are hard to find that can kill a battery. Even lights in the glove box or trunk can drain a battery. 

  1. Temperatures.

Cold and hot can’t kill a good battery, but it will kill an older battery or one that isn’t in good condition. Extreme cold and hot temperatures magnify underlying issues.

  1. Charging.

If a battery dies while driving, it is likely a problem with the charging. Belts that are loose, stretched, or worn tensioners will keep the alternator from doing its job of charging the battery. You may need the alternator changed in addition to a car battery replacement. 

Is it safe to drive my car with the battery light on?

You can, but it isn’t recommended. With a bad battery, a faulty alternator, or bad wiring, your car could lose power at any time and leave you stranded. If the battery light comes on, get your car to the mechanic as quickly as possible. 

What can drain a car battery when the car is off?

In addition to the things we’ve already mentioned, like leaving the lights on or the parasitic draws on a battery, there are other things that can drain a car battery. One is not driving your car far enough or long enough to charge up.  A battery that is older than 3 years can drain fast as well. If the current battery is 3 years old or older and it keeps losing its charge, your best solution is a new car battery replacement. 

How do I find out what’s draining my car battery?

If you have one or know somebody with one, a multimeter can help you find the hidden cause of your car battery draining.  Connect a digital multimeter to the negative battery terminal. Now, remove one fuse at a time and keep watching the multimeter reading. If the reading drops when you pull a fuse, there’s your problem! 

How can you tell if your car battery needs replacing?

Any of the following 7 things are hints that it is time for a car battery replacement: 

  1. Engine is slow starting.
  2. The headlights are dim or your having electrical issues.
  3. The check engine light has come on and stays on.
  4. A bad smell from under the hood around the battery.
  5. Connectors keep corroding.
  6. A mis-hap with the battery case.
  7. The battery is older than 3 years.

At what percentage should a car battery be replaced?

There isn’t a steady number to rely on for knowing when you need a car battery replacement. Batteries don’t wear out steady, they can go from having 90 percent performance today and having only 20 percent in a month or two. Having your battery checked and tested regularly is the best way to reveal when it is time to replace it. Can a car battery last 20 years? Not likely – the longest car battery life is 5 to 7 years, rarely 10 years. 

car battery with testing equipment connected

How do I know what battery my car needs?

When it comes time for a car battery replacement, it is recommended to take it to your mechanic or an auto parts store. They will not only know which battery you need, but they will know how to replace a car battery correctly, so the computer or other components aren’t damaged.