Why Does My Car Battery Keep Dying?

It may be tempting to sell your car battery to a junkyard or dispose of it and get a new one if it keeps dying. The battery may be in good condition. If the battery just died once, there’s a good chance that it won’t happen again.

Several factors can be the culprit if the battery keeps dying, and if you don’t fix it on time, it can keep you stranded in the middle of nowhere.

In this article, I have outlined the possible reasons your car battery keeps dying overnight or while driving. You’ll also learn how to prevent that from happening. Sit back and relax while I walk you through all you need to know.

battery keeps dying overnight

What are the possible causes of why my car battery keeps dying?

Weak alternator, defective charging system, rusted battery terminals, loose connections, weak battery, extreme weather, lights and other appliances left running, and parasitic drains are the common reasons why car battery keeps dying.

Bad alternator or charging system issues

The primary function of the alternator is to keep the battery charged while the engine is running. If the alternator is weak or there’s an issue with the charging system, the alternator may not replenish all the power discharged by the battery. This will lead to the battery draining more power than it should.

In some cases, it could be the alternator and the charging system are in good condition, but you have a loose or weak drive belt.

Alternator issues are one of the most common reasons car batteries die often. However, if your car keeps dying battery and alternator are good, you’re likely dealing with one of the following problems.

You have a Parasitic drain.

All electrical and electronic components in your car use battery power, which drains the battery juice without you noticing.

Things like the car door sensors, shock movement sensors, car alarms, dashboard lights, radio, and all other lights draw the battery power. Though components like the car alarm draw insignificant power, leaving the radio or lights overnight will drain the car battery.

Leaving the headlights on

The headlight draws a lot of power from the battery. Therefore, you don’t have to turn on the headlight and leave it for an extended period while the engine is not running.

No matter how strong the battery is, leaving the headlight on overnight will drain it.

Typically, we all remember to switch off our headlights, but I can’t say the same about Map and Dome lights. Most drivers leave the dome light on, thinking it’ll switch off on its own, only to have it drain the car battery.

Your battery is old/weak.

If your car battery keeps dying when not in use, there are high chances you have an old or weak battery.

Old batteries usually have sulfated battery plates, which prevents them from charging properly and retaining power as new ones. This is one of the reasons some old batteries won’t hold a charge when they get to the end of their shelf life.

Your battery terminals are loose or corroded.

Corroded battery terminals or cables won’t allow the battery to properly release electric juice or get charged while driving.

Similarly, loose battery terminals are one of the common reasons car batteries keep dying. In a real sense, the batteries are not constantly dying, but they’re not transmitting the electric flow needed to start the vehicle or power some electronic components.

Check the battery terminals for loose connections and corrosion; if you’re complaining, my car battery keeps dying while parked. This is one of the most straightforward fixes for batteries that keep dying.

Regularly going on short trips.

This may sound odd, but it’s true. The starter motor takes a lot of energy from the battery to start the engine. The cars need to run for the alternator to recharge the lost power.

The alternator doesn’t have a turbo charge that replenishes the lost power in a matter of a few minutes. It is a gradual charging process. Therefore, if you consistently run short trips, the alternator may not replenish all the power needed to start the vehicle the next time, and your car battery may die often.

You had system modifications.

System modifications could be another viable culprit. For instance, replacing the car radio with one that needs more power will draw more electric current than the system can provide. This will strain the battery, causing it to die more often.

The car is in extreme temperatures.

Car batteries have different cold cranking amps measurements, meaning some batteries perform better in icy conditions while others don’t. Driving with a battery not designed for icy conditions in such weather will cause the battery to keep dying.

If your new battery keeps dying in icy areas, check if the battery is designed to work at that temperature. However, this is the least likely cause, but it’s worth putting into consideration.

new car battery died after a month

How can I find out what is draining my car battery?

We have all been there. If you have been driving for long, there is a high chance that your battery has drained before.

So what’s draining your car battery, and how can you find out? If you mistakenly left something on, you can easily spot it once you jumpstart or charge the battery. Corroded or loose battery cables are easy to spot.

However, a parasitic drain is challenging to identify. Here’s a simplified step to see if you have a parasitic battery drain.

Connect a multimeter

Get a fully charged battery and switch off all electrical and electronic devices in your car. Connect the multimeter to your car battery and set it to the highest Amp settings.

If the multimeter reads above 50 milliamps, you have a parasitic drain. The shock movement sensors, clocks, and other common components should use 20 to 50 milliamps.

Check the fuse boxes.

Locate the fuse box in your vehicle and pull them one at a time while monitoring the reading on the multimeter. I recommend you start with the lowest fuse amperage.

If you remove any fuse and the reading drops significantly, you have seen the root cause of the problem. Read the diagram on the fuse box cover to determine what component uses the fuse.

Once you determine the component drawing the power, you still have to make the extra diagnosis. For instance, if the fuse points to your radio system, check if the power antenna, the radio, or other related component is drawing the power.

If you find yourself in such a case, unplug the components until the power drain stops. Whatever component you removed that stopped the power drain is the culprit.

Fix the culprit

Once you determine what’s draining the power in your car battery, repair or replace it; however, some components require the help of a mechanic. If you can’t fix the problem, contact your mechanic to address it.

How to prevent my car battery keep dying?

Prevention is better than cure. Whether you see your car battery dead after sitting for 5 days or the battery keeps dying overnight, repairing it is more costly than preventing it from happening.

Here are the possible ways to prevent your car battery from dying repeatedly.

  • Clean the battery terminals and cables regularly. Don’t allow it to corrode for any reason.
  • Always ensure the cables are correctly tightened.
  • Do not switch on any electronic device when the battery is not running. (Turn off the radio, AC fan, and other electronics when the engine is not running)
  • Always clamp down your battery. Vibration can weaken the battery life.
  • Always Park in a garage and use a battery blanket in extremely cold weather.
  • Avoid stop-and-go driving. Instead, engage in long-distance driving.

Final Words

A car battery keeps dying because of an old/weak battery, parasitic drain, charging issues, extreme temperatures, system modifications, regular short trips, corroded battery terminals, and loose battery cables.

You can prevent your battery from dying repeatedly by following the preventive measures above. You can fix the culprit yourself with the above guide. However, contact your mechanic if you don’t trust your gut.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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