How do you know if a car battery is dead?

What's the best way to know if a car battery is dead? My car won't start. I think the battery's dead, but I don't know how to be sure.

While there are many reasons a car won’t start, dead batteries are a fairly common cause. To make sure your battery’s really dead, keep an eye out for these tell-tale signs:
  • Your headlights and power are weak, but your car won’t start. When a battery gets low, it might have enough to power your accessories—but not to start your car.
  • Your battery is swollen in size or has an odd smell. These symptoms usually indicate a build-up of hydrogen gas from overcharging or a gas leak from the battery. Both signs indicate permanent damage.
  • Your car radio won’t turn on. If the battery is really dead, not even basic electric appliances will work.
  • Your check engine light is flashing. While this simply means that something is wrong with your engine, the problem could be your battery.
  • Your car starts, then immediately dies. In this case, your battery could have the energy to get started—but not to stay on.
  • Your battery is old. Batteries typically last between 3-5 years. If your battery is in that age range, it’s likely near the end of its life.
If your battery’s started working, but you’re worried it might die again—get roadside assistance with Jerry. With Jerry’s leading roadside assistance, you’ll connect with their nationwide network of over 55,000 service providers. That way, you’ll be covered for jump starts, lockouts, key replacements, and towing—no matter where you are!
Liz Jenson
Answered on Oct 28, 2021

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