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How To Diagnose & Fix Car Battery Not Charging Problems

Car batteries’ major function is to start a car, although they might also be the power source for other car accessories like the headlamp.

When a battery doesn’t hold a charge, it may be due to a simple fault with the connection, or a blown fuse, or more complicated ones such as a faulty alternator.

Troubleshooting the genesis of your car battery issue may be the saving grace of the day. It provides you with detailed insight on where to direct the resources for repair.

Read on for ways to diagnose and successfully fix a car battery not charging problems.

Is It My Car Battery or Battery Charger?

This question may ring a bell to you. Before we move on to make our decision on whether to get a new car battery or to buy a battery charger, we always want to be sure we are solving the real problem and not its facade.

A battery will not hold a charge when the acid components are weak or the battery charger does not deliver the right threshold voltage.

It can also be due to the low internal voltage of the battery. Most car batteries need a certain amount of voltage to kick start charging.

Each of these factors has different symptoms as well as various tactics to diagnose them.

Follow the following steps to successfully troubleshoot and solve each of the problems.

Check the Car Battery

  • Turn on the car’s headlights. A bright light implies that the issue is not with the car battery but with a faulty starter or incorrect wiring. If the light is dim, proceed to the next action.
  • Use a digital voltmeter to check the voltage of your battery. A voltage reading of 12.6 volts and above indicates a battery in good condition. Anything less than that, you have to continue troubleshooting.
  • A voltage reading below 10.6 volts is an indication that your car battery and not the charger is at fault.

Car batteries must have some inherent voltage before they can respond to charging. A discharge below 80 percent of its rated voltage capacity is detrimental to the charging process.

How to fix it?

  • Give it a jump start using another car’s battery
  • If your car battery is more than four years. It is better to replace it with a new one.

Check the Charger

When the car is working, there should be some power drain. Connect your charger and check with a voltmeter if the voltage increases.

If not, this is an indication that your car charger is not working.

How to fix it?

You are advised to replace it with a new one if it’s quite old. However, you can try to replace the charger’s fuse with a new one. It is usually found in the front, with a plastic cover.

Poor Cable Connections

Another reason why your car might have a charging problem is due to a loose cable-to-battery connection.

It is worth checking if the terminals of the battery are tightly connected to the cable. And also, if the terminals are not rusted.

  • A loose wire can be easily be tightened with a screwdriver. If the clamps of the terminal are worn-out, you should consider buying a new one.
  • In the case of a rusted terminal, scrub gently with a wire brush or sand-paper. Clean with a volatile liquid.
  • Also, trace if the negative battery cable (almost back) is well connected to the ground and if there are no wire cuts. The pos red wire should be well connected to the starter without opening.
  • If the above solutions did not work, try to check for a voltage drop in the cables, too much resistance in the wires could also be an issue causing a charging problem.

Faulty Alternator

A faulty alternator means the battery won’t charge when the engine is working. And won’t respond the next time you try to start it.

How to Test the Alternator Step-by-step with a Multimeter

  • While the engine is off, turn on your multimeter and set it to DC volts.
  • Connect the negative and positive lead of the meter to the negative and positive terminal of the battery respectively.
  • Check multimeter reading. It should read about 12.3 volts.
  • Now, turn on the engine and recheck the meter reading. It should read between 13 and 15 volts.
  • Perform a stress test on the alternator by checking the meter reading when accessories like radios, headlights are turned on.
  • Check to make sure there’s no voltage reduction less than the previous voltage reading when the engine was turned off.

If the voltage reading remains the same or reduces when compared to the previous voltage reading, this is an indication that the alternator may be faulty.

What Should I Do If the Alternator is Good

If the test still results in an accepted voltage reading, try to check other parts like:

  • Wrong fuse: Most vehicles’ fuses are 5 amp standard. Check the interior and under-hood fuse box to make sure you’re using the right type.
A short video on testing fuse
  • Loose wire connections to the alternator and grounding: Trace the wirings for cuts. Fasten loose connections. Clean rusted connection terminals until it shines.
  • Belt tension: Alternators rely on rotation and speed to produce a charge. A frayed or elongated belt will reduce the driving speed of the alternator. Physically inspect your belt. Replace a slack or old belt with a new one.

Blown Fuse

Most vehicles have two fuse boxes:

  • Interior fuse box is located beneath the steering column.
  • Second fuse box can be found under the hood next to the battery.

Fuse is meant to mitigate high electrical surges that can damage the car cables and accessories. A blown fuse affects the electrical systems like headlamps, park lights, interior lights, and radios.

By physical inspection, you may detect a blown fuse by its melted appearance.

Before taking out the fuse, you should measure its voltage at both pins of the fuse. The measurements should read 12 volts on each side of the fuse pins.

Otherwise, that indicates the fuse is spoilt. Replace a blown fuse with a new one. It should cost between 10-20 dollars.

Bad Starter

Bad Starters will start the engine but take a whole lot more “juice” to do it. This drains the battery fast but not on the first few starts.

Most auto parts stores will test the starter for free. An engine that won’t crank or an unusual click sign when ignited may be a good sign of a  bad starter.

It’s advisable to replace a faulty car starter with a new one.


How do you know if it’s your battery or alternator?

If your car starts but can’t hold for long, it’s probably the alternator that doesn’t charge your battery.

But if the engine will not start again after it’s off, it’s likely a faulty battery.

Can Autozone test my alternator?

AutoZone has an expert ready to test your alternator if needed.

How many charges does a car need to start?

A voltage between 13.8 to 14.2 volt is needed for a battery to start a car. When more, it can affect the battery. Otherwise, the car battery was not charged.

Read more: The Car Battery Keeps Dying, But The Alternator Is Good

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