New Battery New Alternator Still Not Charging (Quick Fix!)

New battery new alternator still not charging? Here are the reasons why a new battery of the car is not being charged by a new alternator:

  • Check the battery terminal connectors and terminals for corrosion and loose connections.
  • Check the continuity of wirings connected to the battery
  • Check the fuse of the alternator
  • Check the voltage regulator to see if there are problems with the charging system. 
  • Check the alternator belt and pulley for proper fit. 

So, you just managed to install a new alternator and a new battery in your car. But still, the new alternator is not charging your battery. Your car’s battery is responsible for supplying power to all of the electrical components in your vehicle.

If the battery has a low charge, then your car will not start. As a result, it can ruin your family or business trip. In this guide, I will share some useful tips that can help you solve the problem of a new car battery not being charged. 

Why Does My Car Keep Dying With a New Battery and Alternator?

If your car keeps dying with a new battery and alternator, check whether there are any signs of corrosion on the terminals. This means that the battery’s acid is getting mixed up with water and the terminals are corroding. If you see signs of corrosion on the terminals, then your battery is not fully charged. This means that your engine is working overtime and your car is not able to produce enough power.

Why Is My Car’s Battery Light On With New Battery and Alternator?

The battery light of your car is on due to the following reasons:

  • The light circuit is faulty if it is not controlled by ECU
  • The wiring of the alternator is bad
  • Very slipping or broken alternator belt
  • Your car has different circuits for battery sensing, alternator excitation, and warning lamps. Different car models/makes/years use different methods to turn on and off the battery lights. If the excitation circuit is working, but the warning lamp circuit is faulty, the alternator will charge the battery with no problems. Moreover, you have to consult a vehicle model’s manual to understand the car’s electric system.
  • Most newer vehicles have different circuits for battery sensing, alternator excitation and warning lamps, this means that if the warning lamp circuit is faulty but the excitation circuit is working the alternator will charge with no problems.

Before troubleshooting the electrical parts and connections of the battery and alternator, first make sure the alternator is charging properly. To test this, take a multimeter and set it on DC volts.

Check the battery voltage. With the engine off, a fully charged battery will be around 12.6 volts. Ensure the voltage rises to at least 13.5 volts at a minimum when the engine is running (not moving) and the lights are off. 

With the engine at higher revolutions, the volts must be around 14.2 volts. With lights etc switched on and the engine running at higher revolutions the volts must at least never drop below 13.5.

If the voltage of a car battery is between 13.5 and 14.2 with the car running and the battery light is still on, your car might have an indicator problem. That could be due to a wiring problem, ground, or a bad module.

Furthermore, several vehicles implement a charging system that is monitored by the Powertrain Control Module. When a fault is detected, the battery light is illuminated, and a fault code is stored. This is a non-emissions code, so it will not cause a check engine light. More importantly, that code can’t be read with a simple OBD II code reader.

You must utilize a scan tool capable of entering a specific year name, model, and engine. Then a charging circuit code may be stored in the Powertrain Control Module that can aid in diagnosis. There are various faults that can take place that would still allow some function of the charging system.

Must Read: Car won’t start after changing battery

Causes and Solutions of New Battery New Alternator Still Not Charging

Let’s discuss the causes and solutions of the new battery new alternator still not charging.

1. Blown Fusible Linkage Causing New Alternator Not Charging Battery

Some vehicles have a fusible link found under the hood of your car between the battery and alternator.

The fusible link is made of wire that is four gauges higher (smaller) than the rest of the circuit. It is usually red or green in color. Due to a thin wire, a fusible link will not be able to transfer a large current, and thus, it is used as a safety device in the vehicle’s electrical system. In the picture below, the green color wire is a fusible link.

fusible link in a car

A fusible link is a wire that protects electrical wiring from damage due to overload or short circuits. The fusible link protects the wiring from the battery to the alt and other fuses.

The fusible link consists of large strands of a wire wrapped in a fireproof covering. They are thinner than the vehicle’s wiring harnesses they’re connected to.

Fusible links are placed inline between the delicate wiring harnesses and large sources of electrical current in your car i.e. between the battery and alternator.

Fuses blow up due to a power surge, or they wear out. When a fusible link goes out, it could mean that there’s a short circuit somewhere in the car. The fusible link will melt and disconnect the battery from the rest of the car. 

A melted fusible link can be a bit tricky to detect because the wire will melt, but the insulation may appear unaffected.

Follow these steps to test the blown fusible link:

  • Open the bonnet and find the fusible link with the help of the schematic diagram in the vehicle’s service manual.
  • Put positive probe of ohmmeter on the B post on the alternator and the negative probe on the plate on the fuse box. The reason for putting the second probe of the ohmmeter on the fuse box is that it comes after the fusible linkage system i.e. right before the battery. So, if fusible linkage has no fault, the resistance on the ohmmeter will be close to zero.
  • Also, measure the resistance between the battery negative post and the engine block. It should also be close to zero. If it is more than 1, chances are that the fusible link has blown out.
  • Lastly, visually inspect that the wiring to the fuse link is not corroded or shitty.

Note: When doing ohms, make sure there is no k or M showing on the display because a reading of say 0.276 with the M showing means 276,000 ohms.

To replace the fusible link, check out the below video:

2. Blown Fuse Causing Battery Not Charging

fuse box in a car

The car fuse box is located under the hood near the battery that protects engine components including the engine control unit (ECU), cooling fan, and battery. When the fuse is blown in the fuse box, the current could not flow to the battery, due to which the battery will not charge.

Usually, you have to check the fuses linked with the starter and alternator. If the alternator fuse is blown, the battery will not be charged. If the starter fuse is blown, the battery will not be able to supply power to the starter motor, due to which your car will not start.

Here are the following types of fuses”

  • Micro2 (5-30 amp)
  • Micro3 (5-15 amp)
  • Mini & Low Mini (2-30 amp)
  • Regular ATO/ATC (1-40 amp)
  • Maxi Heavy Duty (20-100 amp)

To identify and replace a faulty fuse in the car fuse box, you can do the following steps:

  • Turn the ignition off and disconnect the battery.
  • Find the fuse box in your car. The fuse box in a car can be situated in any number of different places. In some instances, you’ll be able to find the fuse box under the bonnet of the car. But in others, you might have to look underneath a seat or in a compartment underneath the steering wheel in your car.
  • Get your vehicle’s manual to analyze the fuse box diagram. This will tell which fuse is powering the component of your vehicle. 
  • From the diagram, check which fuse is linked with the alternator and starter. The location of the alternator fuse in a car depends on the model of the vehicle. Also, note that in some cars there is no fuse linked with the alternator. So, it all depends on the model of your vehicle.
  • Pull out the blown fuse using a fuse plier.
  • Take a digital multimeter (DMM) and set it to ohms setting.
  • Connect one meter lead of DMM to one of the fuse’s terminals. Connect the other meter lead to the other fuse terminal. 
  • If your meter reads out of limits, the fuse is bad.
  • You need to identify the fuse of the same type, size, and current rating. Avoid replacing a 10-amp fuse with a 30-amp fuse. The 10-amp is designed to blow at a lesser current rate. If a higher current passes through the fuse with a lower current rating, the component will damage.

You can check out the below video to learn about how to identify blown fuse in the fuse box.

In some cars, the alternator fuse is not found in the fuse box as you can see in the video below:

Note: If there is no faulty fuse, check the wire to the fuse that is connected with the alternator and battery. If the wire is corroded, you need to replace it.

3. Corroded and Dirty Connection/Wiring At Battery Terminals

battery terminals

If you have installed a new alternator and new battery in your car, but still your car battery is draining or not charging, the reason might be a corroded and dirty connection at battery terminals.

When the terminal corrodes and dirt accumulates, it can cause the electrical connection between the positive and negative terminals to become loose

There are three to four wires connected to the car battery, depending on the car model. Generally, the two wires are connected with the positive terminal of the battery.

One wire comes from the alternator, and the other wire is directed from the battery positive terminal to the starter motor. The wires from the negative terminal of the battery are directed to the engine block and chassis.

Here is how to detect the issue of corroded terminals of a car battery:

  • Start by visually inspecting the battery-terminal connections.
  • Use wire brush to scrap off the rust on the battery terminals.
  • Clean the white or green deposits on the car battery terminals. If it is a lead acid battery, clean the terminals with a solution of baking soda formulated by a teaspoon of baking soda mixed with a cup of water. You can also use this cleaning spray to remove the dust off the battery terminal.
  • If the terminal connectors of a battery are damaged, get a new one.
  • Tighten all the wiring connections to a battery. Turn the bolts or screws clockwise using an adjustable wrench until they no longer move. 
  • Also, inspect the nut holding the battery cable to the starter stud. 
  • Next, look for wear and tear on battery wirings. Carefully examine them for breaks or brittleness that could expose the wires within the casing.
  • Lastly, don’t forget to check if the grounded connection of battery is corroded.

4. Poor Voltage Regulator Causing New Alternator Not Charging Battery

The voltage regular is also a part of the charging system of a battery. The voltage regulator is a device that allows the alternator to supply the required amount of power to the battery.

The location of a voltage regulator depends on the make and model of the car. The voltage regulator is either inside or next to the alternator. The voltage regulator ensures that the maximum amount of voltage in the electric circuit of the battery is kept constant. 

If the voltage regulator fails, it will prevent the alternator from producing sufficient power to charge the battery. As a result, the battery will not charge and car won’t start.

Here is how to detect degraded poor voltage regulator issues:

  • Set the gear position of your vehicle to neutral
  • Open the bonnet
  • Find the car battery
  • For a voltage drop test, take a digital multimeter. Connect its red probe with positive terminal of a battery and black probe with negative terminal.
  • While the car is not running, the voltage across the battery should be slightly over 12 volts.
  • Now start the car. The voltage should now jump to 13.5 to 14.2 volts.
  • Now increase the car rpm. If the voltage across the battery peaks above 15V, the regulator has failed.
  • If you turn on the headlights while the car is running and the voltage drops very much, it might be a battery problem as well.

5. Broken Serpentine Belt Causing Alternator Not Charging Battery

The alternator is the main component of the electrical system of the vehicle that converts mechanical energy from the engine into electrical energy by charging the battery. The alternator is connected to the engine by a belt called the serpentine belt.

The alternator and the serpentine belt are connected by a pulley. The serpentine belt is responsible to transfer the rotating speed from the engine crankshaft to the alternator via crankshaft pulley.

Check the below video for a better insight into the serpentine belt role in the engine.

When the serpentine belt breaks, the alternator will not run and stop charging the battery. If you do not repair the problem, it will damage the engine and cause severe problems in the future. The serpentine belt needs to be replaced every 30,000 miles.

Here is how to detect a damaged serpentine belt:

You can easily spot a damaged serpentine belt by looking for any unusual noises coming from the engine. The most common noise you might hear is squealing noise.

Check out the below video to learn about the failure models of the serpentine belt.

You can follow these steps to solve the damaged serpentine belt issue:

  • Park the vehicle on a flat surface.
  • Turn off the ignition switch and open the bonnet.
  • Wear protective gloves.
  • Find the serpentine belt spring tensioner that offers the amount of force against the belt to keep it tight. 
  • Grab a serpentine belt tool to loosen the serpentine tensioner. It is a long thin wrench with different sockets.
  • Replace the damaged serpentine belt.
  • Make sure that new belt has the same diameter, thickness and the tooth shape.

You can also check out this in depth guide on replacing serpentine belt.

Final Thoughts

In summary, there are a few key reasons why a new battery and alternator may not be charging properly. Corroded or loose battery connections can prevent proper electrical contact.

Blown fuses or fusible links can disconnect the electrical circuit. The voltage regulator may be faulty and preventing the alternator from charging sufficiently. And a broken or slipping serpentine belt can fail to turn the alternator to generate electricity.

Carefully inspecting battery terminals, testing fuses, checking belt condition, and testing voltage can help diagnose the issue.

Replacing damaged wiring, cleaning connections, replacing fuses, adjusting belt tension, or replacing a faulty regulator as needed should resolve the charging problem with a new battery and alternator.

Proper electrical system maintenance and diagnostics are key to ensuring your vehicle’s charging system functions optimally.

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