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How to Rejuvenate a Lead-acid Battery-Time and Methods

Jan 20, 2021   Pageview:88


A lead acid battery is a rechargeable battery that is widely used as it supplies high surge currents. This means the cells have a relatively large power to weight ratio. Lead-acid batteries are cheap and find heavy application in motor vehicles, thus providing the high current required by starter motors. They also find application in trucks, electric cars, and golf carts, among others.

Like any other rechargeable battery, a lead-acid battery has its problems. As you continue using it, the performance characteristics reduce over time. This is mainly due to the problem of sulphation. When sulphation sets in, the battery is likely to be damaged, and it is a sign of a dead battery.

However, if you have dead batteries in your store due to sulphation, you should not discard them. The following article will realize that there are ways of rejuvenating the dead lead-acid battery through de-sulphation.

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When will you check a lead-acid battery?

A new lead-acid battery gives an optimum performance under a load. As you use it, this performance reduces. Below are some of the common signs that indicate the time to check your lead acid battery:

  • If the lead-acid battery that cannot hold charge will appear fully charged and show a right voltage level on a voltmeter drops drastically under a load.

  • If you fully charge your lead acid battery and it won’t start your car, then you need to check it with a tester.

  • When the voltage starts to drop drastically after a full charge to less than 12.2V for a sealed lead acid battery under no load, it is high time you check it.

  • When the lead-acid battery starts leaking, this is an indication of damaged cells.

  • When the led acid is reading 0 volts, the chances are that the battery has experienced a short circuit and needs checking.

  • When the battery cannot reach higher than 10.5 volts when being charged, this indicates dead cells.

  • If you see a bulge or a bump in the case, it is time you check the lead-acid battery for problems.

  • When staring a car, it produces a click instead of the usual sound.

  • The headlights of the vehicle become dark and shine only when you accelerate.

  • The car does not start usually. It begins with a jump.

  • Electrically operated components fail to work like car windows or the radio.

  • The car fails to start when you turn the battery on.

How do you bring a dead sealed lead acid battery back to life?

A sealed lead-acid battery has a cover on the top of the battery. Remove it with a little flat screw, and you will see holes covered by rubber caps. Remove the caps as well. The apparatus needed for the process include a voltmeter or multimeter, syringe, battery charger or power supply, crocodile cords used with PSU, and distilled water.

Before performing this procedure, ensure that you wear protective gear, including chemical gloves, an apron, and safety goggles. The steps are outlined below:

?Measure the lead-acid battery voltage.

Connect the multimeter to your sealed lead acid battery and check the voltage. A good lead-acid battery will read about 12.7V. If the voltage is too low, say 11V, the process of reviving Is carried out.

?Check the battery cells.

If the sealed lead acid battery is a maintenance-free battery, remove the lid with a screwdriver. Remove the caps. Wipe any wet spots and look inside the cell for a dry white fabric. In case you see a brown fabric with white lumps on the sealed lead acid battery, the battery is sulfated.

?Add distilled water

Using a syringe, fill each cell with distilled water and check if the fabric is absorbing the distilled water. Shake the lead-acid battery slowly and let it rest for about 15 minutes.

?Turn on the PSU

Connect the multimeter to show the amount the battery is drawing. Set the multimeter to 10A and connect it with the charger and the battery in series.

The battery should draw about 100 to 200Ma when you connect the multimeter. Set the PSU to 14v. The battery should now draw 500 to 1000Ma.

Leave the battery and calculate how long the battery should charge.

The battery should now be working again. Cover the battery, and it is ready for use again.

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How do you remove sulfation from a lead-acid battery?

Sulfation occurs inside lead-acid batteries when the electrolyte starts to break down. As the electrolyte breaks up, sulfur ions become free and form crystals. These ions then stick on the lead plates of the battery, resulting in lead sulfate crystals.

The process of de-sulphation is simple and effective. First, identify the bad cells.

  • Before checking for bad cells, charge the lead-acid battery for 12 hours. Disconnect the lead-acid battery from the charger and allow it to rest for about 10 minutes.

  • Open all the battery caps.

  • Fill all the cells with distilled water to the optimum water levels.

  • Measure the terminal voltage battery. A value in the range of 12 V will be rad for a fully charged battery, and a value lower than 11.8 v will indicate a cell imbalance. The malignant cells will have different colors of plates than the other cell plates.

The process of de-sulphation follows:

  • Connect a battery trickle charger to your lead acid battery and allow charging for about a week. The slow charging rates dissolve the de-sulphation that damages the battery.

  • Wire in an electronic de-sulfate device that de-sulfates the battery acid solution

  • Add a chemical desulphator to the filling ports on the lead-acid battery. The chemical dissolves the sulphation and revives old lead-acid batteries.

While performing the procedure above, ensure that you wear protective clothing, including goggles and gloves.


Lead-acid batteries have a lifespan of about nine years. When the battery gets damaged, you should not be quick to discard it. The procedure above of reviving the dead lead acid battery can help cut on purchasing a new battery. You can visit a certified battery dealer for assistance.


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