How to rebuild lead acid battery : 9 easy steps

rebuild lead acid battery

We rarely think about our car’s battery up until it fails to take charge and fails. Instead of going directly to get a replacement, you can try to rebuild the battery. Here, we’ll show the best and safest way to rebuild a dead lead acid car battery.

Rebuild lead acid battery

The battery is one of the few car components we can go without thinking about for a month or two. This is why when it dies, it’s usually a surprise for most people. A lead acid battery is considered dead when there is an accumulation of lead sulphate particles that prevents the sulphuric acid in the battery to make contact with the metallic plates. A chemical imbalance is caused in the electrolyte causing the battery to fail.

Before replacing the battery, there is one main method used to recharge a dead battery. This method restores the battery to around 70% to 80% of its original capacity. This is enough to get you a few more years of use at almost zero cost. For this recharging procedure, you will need a few components.

Related: How to refurbish a car battery.

What items are needed to rebuild lead battery?

Before you begin the recondition process, you need the following items

  • Protective gloves for safety
  • Protective googles
  • A screwdriver
  • A battery charger
  • Distilled water

Steps to follow to rebuild lead acid battery

Once you have the items above, you can begin the process of reconditioning the battery.

Step 1 to rebuild lead acid battery

Wear the protective gloves and googles first. This is because when replacing the battery, you need to go through the cells reservoir. The reservoir contains sulfuric acid which is very corrosive to the skin and eyes.

Step 2 to rebuild lead acid battery

Remove the lead acid battery from the hood of the car and place it on a stable flat surface. After this, remove the six battery cell caps that are located on the top of the battery. There are six slot because each produces 2 Volts, providing a total of 12 Volts which is the rating on car batteries. Use a screwdriver or your fingers to unscrew the caps. Place the caps somewhere safe.

Step 3 to rebuild lead acid battery

After removing the caps, check inside the battery for the level of fluid in the six cells. Use a dipstick for this. If the battery is really dead, you will find that the level of fluid is below the recommended minimum mark. The fluid, sulfuric acid, acts as the electrolyte. Low fluid level means there are very little electrons moving between the two lead plates which in turn means no power is flowing through the battery. The metallic lead plates act as the positive and negative terminals. If left below the minimum mark for a long time, the plates start corrode.

Step 4 to rebuild lead acid battery

Here, the process of replacing the fluid begins. But instead of sulfuric acid, we will use distilled water. Pour in the distilled water into the six open cells. Ensure that you do not overfill the water since the chemical reaction increases the temperature causing the fluid to expand. The water mixes with the little acid inside and the rebuilding process begins with this chemical reaction. But for this process to be complete, a little electric current is needed and here is where the battery charger comes in. The current is needed to heat up the electron to start flowing into the plates.

Step 5 to rebuild lead acid battery

Put back the cell caps back on after putting the distilled water.

Step 6 to rebuild lead acid battery

After the caps are back on, it is time to connect the battery charger. Use the spring clamp on the black charger cable to connect to the negative terminal of the battery. Usually, the terminal is labelled with a ‘Neg’ or minus sign. Use the other spring clamp, the red one, to connect to the positive terminal which is also labelled on the battery. Usually, the terminal has a red ring around it. Once the battery charger is set, move on to the next step

Step 7 to rebuild lead acid battery

For recharging to start, set the battery to the lowest power setting known as trickle charge or mode. This should be done because the process is slow as the distilled water gets acidified. As the water gets more and more acidic, electron flow also increases and the battery gets slowly recharged. The previous corrosion that had formed is slowly eliminated as the reconditioning goes on

Step 8 to rebuild lead acid battery

Turn the battery charger on and set at the lowest power setting. Leave the acid battery to recharge for about 36 hours. In this time, it’s important to check whether the process is working. Do this by touching the sides of the battery. You will find that it gets warmer over time indicating that the recharging process is working smoothly.

Step 9 to rebuild lead acid battery

After 36 hours, turn off the charger and disconnect the spring clamps from battery terminals. For safety purposes, always start with the positive end. In this step, you will also find the battery at its warmest indicating the battery is fully rebuilt and is ready for use. There are times you may find the battery is cold or it’s only hot partially. When this happens, you will need to replace the battery because it only means that the fluid level is extremely low and the plates got too corroded to be rebuilt using this procedure.

An important factor to note is that you should only use distilled water. Regular tap water contains impurities in form of minerals that may prevent the flow of electrons and hinder the process of water acidification.

Related: How to refurbish a car battery 

When do I have to replace my battery?

The reconditioning process of a lead acid battery does not always works. The following are unique situations where you will need an actual battery replacement:

  • If you’ve been using the battery for three years or more
  • When the lead plates are too corroded to recharge
  • If the fluid level drops extremely low

In conclusion, there is no need to buy a new battery when you can recharge it. Although this process takes over a day, it is cost effective and will provide service for three or four more years.

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