Why Does Car Battery Keep Dying But Alternator Is Good?

A dead car battery is as frustrating as it can get on an already busy day. If it happens once or twice in a blue moon, then it can be overlooked. 

However, if your car battery keeps dying over and over again even when you have checked that your alternator is working perfectly fine, then there must be some undetected issues going on with your car. 

A car battery can keep dying even if the alternator is good because of faulty battery, loose battery connection, parasitic drain or failure in the charging system.

To avoid this distress, you need to figure out the cause and here we’ll help you find out why your car battery keeps dying but alternator is good.

Why Does Car Battery Keep Dying But Alternator Is Good?

If a relatively new car battery dies suddenly, the first thing anyone will check is the alternator. However, upon discovering that the alternator is good and running well, the question will arise as to why the battery is dead. There could be a few reasons behind the car battery dying. 

Bad or Faulty Battery

Car battery provides the current necessary to operate the car. It is constantly being discharged and partially charged. Over time, the insides of the battery gets corroded and weak. 

If the battery is old and damaged like this, no matter how much current the alternator provides to it, the battery won’t hold the charge. These kinds of batteries keep discharging even when you turn the engine off and eventually die.If this happens, then it is time to get a new battery for your car.

Loose or Corroded Battery Connections

If the connection to the alternator and the battery is loose or gets corroded over time then the alternator can’t recharge your battery. In case, both your battery and alternator are perfectly fine, you should look for corrosion or damage to the internal cables of the car. 

These kinds of faulty connections create resistance and prevent the battery from charging properly.

Check the terminals and cables of your car and if you notice a white fluff then you are dealing with corroded battery connections. Regularly clean your terminals with vinegar, wire cleaners, sandpaper and soap in a proper way to avoid this issue.

Parasitic Drain

A parasitic drain occurs when the engine has been turned off but the car still drains charge from the batteries. When the engine is turned off, the alternator doesn’t recharge the batteries anymore. So, if there is something in the car that drains more charge from the battery, it reduces the lifetime of the battery. 

Parasitic drains can happen because of a short circuit, a running interior light like the glove box or the trunk light. Sometimes you might accidentally leave the headlights on or forget to turn off the radio. 

Things like this cause the battery to drain overnight so the next time, you might find yourself unable to start the car because the battery is dead.

In order to avoid parasitic drains on your battery, check whether or not you have turned off the headlights and glove box lights after turning the ignition off. Moreover, make sure that the door, trunk and windows are closed fully before leaving the car.

Drained Battery

If you leave a car battery unused for too long, at one point it stops working. Even if the car is not running, the battery always draws a small amount of current in itself. 

When you don’t drive your car for a long time, the current eventually drains the complete battery and leaves it dead. Since the ignition isn’t turned on, a good alternator can’t recharge the battery here either.

Not Enough Time To Recharge

If you start the car and turn it off again continuously, the alternator doesn’t get enough time to recharge the battery. Frequent starts and stops draws a lot of current and reduces the charge in the battery. 

But taking too short trips doesn’t provide enough time for the alternator to restore that much charge. As a result, the battery ends up being dead eventually.

Extreme Weather

Too cold or too hot both can be risky for a car battery. If the battery is a little old, then leaving the car outside in the harsh weather can weaken it more and cause it to die unexpectedly. 

How to Identify Why Car Battery Keeps Dying

Now that you are aware of the plausible causes, you can do some basic routine checkups and identify the exact reason your battery keeps dying.

  • Test the car battery with a voltmeter or a load tester. It will compare the battery to a starter motor and show whether the battery is failing or not.
  • Check electrolyte levels in the battery. If the electrolytes of a lead cell battery drops below the lead plates then fill it with distilled water up to the top.
  • Ensure good battery maintenance. It can prolong the battery life to a great extent.
  • Always check the lights and other accessories of the car.. Don’t leave anything on for an extended period of time. 
  • Periodically check for corrosion in terminals and cable connectors. If you see any corroded material inside, make sure to clean it up with the help of baking soda, white vinegar and a bristled brush.
  • Check if the cable connections are all tight and secure.  
  • You can get a battery tender if you don’t plan on driving your car for a long time. It can also prevent the battery from dying in too cold weather as well.

Frequently Asked Questions

1. Can blown fuse be the reason for battery drainage? 

Well no, the power drain can’t only be caused by the fuse itself. It does, however, show where the drain on power is coming from. If you pull the fuse and the battery drain slows down noticeably, then there’s an issue on the circuit.

2. Is it possible that short wear is reason for battery draining? 

In some situations, short circuits can cause a parasitic drain that drains the battery. Most of the time, the signs of a short to power or ground are the same as those of open circuits. Therefore, when you figure out that there has been issues with short wear you should look after the matter immediately. 

3. What drains your car battery most of the times? 

Problems with your car’s electrical system along with broken fuse, bad installation, and bad wiring can severely cause car battery drainage.  This drainage issue can also strike even when your car engine is turned off. Therefore, it’s essential that you maintain the car batteries on a regular basis for optimum performance.

Bottom Line 

As we can see, any of these could be the reason as to why the car battery keeps dying but alternator is good. You can follow up the steps to check which one is causing the battery to die in time and take necessary measures to prevent the battery from dying completely. 

Even the best alternator out there can not revive a dead battery. By being a little careful about the causes, you can avoid buying another expensive car battery.

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