How to Tell the Difference Between a Bad Battery and a Bad Alternator

If your car won’t start, the odds are good that either the battery or the alternator is to blame. Both are part of your car’s electrical system, and they both need to be in good working order to get your engine running. Knowing the signs of a bad car battery versus an alternator can tell you which is causing your problem.

Bad batteries and alternators aren’t the only problems you might face with your vehicle. For protection when accidents, theft or injury occurs, you need dependable auto insurance coverage. Talk to Farm Bureau to find out more.

Bad Car Battery Symptoms

Your car’s battery sends a charge to your engine so it can start. It also keeps your electrical system running when your car is turned off.

Car batteries generally last three to five years, so if yours is older than that, it might be getting to the end of its lifespan.

To tell if a car battery is bad, look for signs like:

• It’s hard to get your car started, or it starts and dies immediately.
• You hear a clicking sound when you try to start your car.
• You need to jump start your car. (If you’re in a cold climate it could be the cold, not your battery, that’s causing issues.)
• Your dashboard lights are dim or they flicker.
• Your radio won’t turn on or it works intermittently.
• You notice battery corrosion, which can look like something white, blue or green on your battery. You can clean off the corrosion to make your battery last longer, but corrosion means your battery is leaking acid so it will need to be replaced.
• Your battery smells like rotten eggs, which is another sign of an acid leak.
• Your battery looks swollen. If this is the case, don’t touch your battery or replace it yourself. It could be overheating and could explode. 
• You see a low voltage light on your dashboard. This could be a sign of either a bad battery or a bad alternator.

Bad Alternator Symptoms

If your battery isn’t that old and it doesn’t seem like it’s the problem, your alternator might be to blame. Alternators usually are good for seven to 10 years, so if you know yours hasn’t been replaced, it may be responsible for your car trouble.

Signs of a bad car alternator include:

• A jump start doesn’t work, or your car starts and dies a few minutes later.
• It feels like your car is vibrating when you drive. That’s because the alternator isn’t working well enough to ignite the spark plugs. 
• Your dashboard lights and headlights are brighter or dimmer than usual.
• Your headlights get brighter when you drive faster.
• Your AM radio goes in and out, or you hear static or a whining sound.
• Your engine makes growling or squealing sounds that you notice more when you turn on the headlights or radio.
• You smell burning rubber, which could mean your alternator is overcharging the battery.
• You see a low voltage light on your dashboard.

What Should You Do Next?

You shouldn’t drive a car with a bad battery or alternator since you could stall or get stranded. 

If your battery is to blame, you can either replace it yourself or have an auto repair professional do it. Depending on your car, new batteries can cost anywhere from $100 to $350 depending on what your car needs and without labor.

Alternators are harder to replace, and you’ll probably want a pro to handle it. The cost of replacing an alternator ranges from $500 to $900 for the part alone and depends on your car model. .

Make Sure Your Car Is Protected

While you’re taking care of car maintenance and repairs, take a look at your auto insurance coverage as well. A Farm Bureau agent can review your policy and make sure you have the protection you need.