Dead Cell in Car Battery: How To Fix It With 9 Easy Steps?

Dead cell in car battery can turn any smooth drive into a roadside hiccup. But what if you are told there’s a way to tackle this issue head-on?

Dead Cell in Car Battery ~ Ran When Parked

In this read, you’ll uncover the mystery behind the dreaded dead cell and get a simple, step-by-step guide to breathe life back into that battery. So, if you’re keen on turning a potential roadblock into a pitstop, you’re in the right place.

How To Fix a Dead Cell in Car Battery With Nine Easy Steps?

You can fix a dead cell in a car battery by prioritizing safety, assessing the battery, charging it, checking electrolyte levels, equalizing the battery, adding Epsom salts, recharging, rechecking specific gravity, and finally, reconnecting and observing the performance of the battery.

1. Safety First

When addressing an expired cell in a vehicle battery, it’s paramount to prioritize safety. Handling a car battery, especially one with an expired cell, exposes one to the risk of acid spills or even explosions. Wear protective gloves and safety glasses before embarking on any repair or assessment.

Additionally, working in a well-ventilated area minimizes the risk of inhaling harmful fumes.

2. Battery Assessment

Before diving into the repair process, it’s essential to determine the state of the vehicle battery. Using a voltmeter, take a voltage reading. If it’s below 12.6 volts, it indicates a potential car battery one cell dead or that the battery itself may be on its way out.

Performing Battery Assessment ~ Ran When Parked

Visually inspect for any signs of swelling, leaks, or cracks. If any of these are present, it’s best to replace the bad battery entirely.

Remember, being aware of the dead cell in car battery symptoms, signs of a bad car battery vs alternator, what causes a dead cell in a car battery, how long can a car battery last with a dead cell, and can you jump a battery with a dead cell can be beneficial for you and your vehicle battery’s health.

3. Battery Charge

Give your battery a full charge. A standard charger that provides a slow charge is preferable. Rapid charging can sometimes do more harm than good, causing overheating and potentially damaging the bad cell battery further. Ensure that the charger is compatible with your battery type.

Note that charging can revive a battery unless the cells are entirely damaged, which is a situation that demands a more advanced fixing procedure.

4. Electrolyte Level Check

The electrolyte solution in a battery consists of sulfuric acid and distilled water. Over time, this solution’s level can decrease due to evaporation or leakage. To check, open the battery caps. The electrolyte should ideally reach the bottom of the fill ring.

Electrolyte Level Checking of Car Battery ~ Ran When Parked

If it’s below this level, you can top it up using demineralized water, ensuring you don’t overfill. It’s essential to use demineralized water as tap water has minerals that can harm the battery cells.

5. Equalization

Equalizing a battery refers to the process of restoring the charge balance between the cells. This method is primarily used for lead-acid batteries. It involves charging the battery at a higher voltage rate until all cells reach a full charge.

It’s crucial to monitor the voltage and specific gravity during this process. Equalization helps remove sulfate crystals from the plates and balance the electrolyte concentration across the cells.

6. Add Epsom Salts or Magnesium Sulfate

Magnesium Sulfate can sometimes rejuvenate a battery dead cell. By adding a mixture of demineralized water and Magnesium Sulfate to each battery cell, sulfate build-up on the battery plates can be dissolved, enhancing the battery’s capacity and performance.

To do this, heat half a quart of demineralized water and dissolve approximately 7-8 ounces of Magnesium Sulfate in it. Once dissolved, use a funnel to add the solution to each cell until it’s full.

7. Recharge Again

After carrying out the above interventions, especially after adding Magnesium Sulfate, it’s essential to give your battery another thorough charge. This secondary charge ensures that any alterations made to the battery composition, such as the addition of new electrolytes, are integrated.

As before, use a slow-charging method to prevent overheating and further damage. After charging, monitor the battery’s performance to ascertain if the expired cell issue has been resolved.

8. Recheck Specific Gravity

Specific gravity measures the density of the electrolyte solution in the battery cells compared to pure water. It’s an effective way to gauge a battery’s state of charge and overall health. After any intervention, like adding Magnesium Sulfate, it’s prudent to recheck this value using a hydrometer.

Draw electrolyte into the hydrometer, note the reading, and return the sample. For a fully charged lead-acid battery, the specific gravity usually falls between 1.265 and 1.299, but it can vary based on battery type and manufacturer.

Consistent readings across cells indicate balanced health. However, a variation of more than 0.050 between cells could mean one or more cells are damaged or dead.

9. Reconnect the Battery and Observe Performance

Once you’ve undertaken the various steps to address the expired cell issue, it’s time to put the battery back to the test. Reconnect the battery, ensuring the connections are clean and tight. Negative terminal connections should be restored last to avoid short circuits.

Once connected, try starting the car engine. If it starts smoothly, let it run for a while, then turn it off and try restarting. Monitor the vehicle’s performance, looking out for signs like dimming lights or sluggish cranking. These could be indicators that the battery, despite interventions, still has underlying issues.

If everything seems normal, it’s still wise to periodically check the battery’s performance, ensuring longevity and consistent health.

How To Jumpstart Your Car When The Battery Dies?

You can jumpstart your car when the battery dies by positioning a donor vehicle or car close (ensuring both engines are off), connecting positive jumper cables correctly, starting the donor vehicle, reviving your dead battery, and removing the cables in order.

1. Identifying Signs of a Dead Car Battery

Some telltale signs of a dead vehicle battery include dim headlights, a weak or non-existent horn, and a sluggish engine start.

Identifying Signs of a Dead Car Battery ~ Ran When Parked

If the dashboard lights flicker when trying to start the car, it’s another indicator of a car battery issue.

2. Gathering Essential Jumpstarting Equipment

When trying to jumpstart a vehicle, having the appropriate tools is really necessary. Such tools comprise a set of jumper wires of a high grade, a car that is in working condition and has a healthy battery, and a pair of protective gloves.

3. Positioning Both Cars Safely

Place the vehicle that will be used as a donor as close as possible to the vehicle with an expired battery without touching it. Next, you should check that both the vehicles are stopped and their parking brakes are engaged before you leave.

4. Connecting the Jumper Cables Correctly

Connect the positive (red) clamp to the expired battery’s positive terminal. Attach the other red clamp to the good battery’s positive terminal. Connect the black (negative) clamp to the healthy battery’s negative terminal and the other black clamp to an unpainted metal surface on the dead vehicle.

5. Starting the Donor Vehicle

Start the car that will be used as a donor and allow it to run for a few minutes. This enables the living battery to supply power to the expired battery, which may result in the expired battery being partially recharged.

6. Reviving Your Dead or Expired Battery

Once the jumper cables are securely connected, and the donor vehicle is running, it’s time to breathe life back into your expired battery. Let the donor vehicle run for a few minutes, allowing power to flow and charge your expired battery.

Reviving Your Dead or Expired Battery ~ Ran When Parked

This process ensures that your battery receives adequate energy to kickstart the chemical reaction within. After a few minutes, try starting your car. If it starts successfully, allow your engine to run for at least 10-15 minutes.

This further ensures that the alternator, which charges the battery when the car is running, replenishes some of the lost charge, preparing your battery for the next time you need to start your vehicle.

However, if the car doesn’t start, there might be more severe issues than just a dead battery cell, and seeking professional assistance might be the best course of action.

7. Removing the Cables in Sequence

To begin, loosen the clamps that are marked with a minus sign, beginning with the dead vehicle, and then move on to the clamps that are colored red. During this process, you must make sure that they do not come into contact with any metal.

How To Clean Corroded Battery Terminals? Effective Method Found!

You can clean corroded battery terminals by disconnecting the battery (starting with the negative terminal), applying a mixture of baking soda and water to the corrosion, scrubbing gently using a wire brush, rinsing with water, drying thoroughly, and applying petroleum jelly before reconnecting.

1. Safety Precautions Before Starting

Dealing with corrosion means dealing with potentially hazardous chemicals and reactions. Before embarking on the cleaning method, ensure you’re in a well-ventilated area, away from open flames or sparks. Wear gloves to protect your hands from any corrosive substance sitting on the battery terminals.

2. Gathering Tools and Materials Needed

To combat corrosion effectively, you’ll need a few basic tools. These include a wire brush, a mixture of baking soda and water to act as a cleaning solution, clean rags, and petroleum jelly or a commercial terminal protector to seal the terminals after cleaning.

3. Disconnecting the Car Battery

For disconnecting the battery correctly, always start by disconnecting the negative terminal first. It will minimize the risk of a short circuit, which might occur otherwise.

Once you get the negative terminal disconnected, you can proceed with disconnecting the positive terminal of the battery.

4. Identifying the Type of Corrosion

Inspect the terminals. White or bluish powdery substances often indicate lead sulfate corrosion, which is commonly seen on car battery terminals. On the other hand, green or bluish-green fuzz is a sign of copper sulfate corrosion, typically seen on copper connectors.

5. Applying the Cleaning Solution

Generously apply the mixture of baking soda and water to the corroded areas of the battery. The solution neutralizes the acid and breaks down the corrosion. It’ll fizz upon contact. This is the reaction you want, as it means it’s working.

6. Scrubbing Away the Corrosion

Only applying the solution isn’t enough for cleaning. Hence, you’ll need to use a wire brush to scrub vigorously at the corroded areas until all visible corrosion has been removed. Don’t forget to ensure you get into all the nooks and crannies.

7. Rinsing and Drying the Battery Terminals

Once you are satisfied with the scrubbing step, rinse off the terminals with demineralized water. It ensures that any residual baking soda or corrosion is washed away and no longer sits on your battery. Dry the terminals thoroughly using a clean rag.

8. Applying a Protective Layer and Reconnecting the Battery

To prevent future corrosion, apply a thin layer of petroleum jelly or a commercial terminal protector. It seals the terminal and acts as a barrier against moisture and other elements. When reconnecting, start with the positive terminal before moving to the negative one.


Journeying through the world of car maintenance can seem difficult, especially when faced with a dead cell in car battery. Yet, as you’ve ventured through today, reviving that stubborn battery is doable with a bit of patience and the right steps.

Now, you’re armed with the knowledge to tackle this common automotive hiccup, ensuring your car remains a reliable companion for many miles ahead.

  • Empowerment is key: Know the signs and take control of your car battery’s health.
  • Safety first: Always prioritize your safety and that of your vehicle.
  • Magnesium Sulfate to the rescue: A surprising remedy for those battery blues.
  • Knowledge is power: Understanding the intricacies can be the difference between a quick fix and a tow truck call.
  • Seek expertise when in doubt: If DIY doesn’t do the trick, professionals are just a call away.

So, next time you’re greeted with that dreaded silence of a non-starting engine, remember, you know how to fix a dead cell in a battery!

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