What are Dead Cell in Car Battery Symptoms

How to Tell if a Car Battery Has a Dead Cell?

A dead car battery is a big problem especially when there is no automobile workshop nearby. It is important to identify a dying battery before it goes off completely and, take measures accordingly and in time. Here are some symptoms that you can look for to tell if a cell in your car battery has gone dead/bad:

  • Dim dashboard lights and battery gauge is an indication that a cell has died in your car battery or battery need to be charged.
  • If your car’s headlights are dim, you might want to check for a bad battery.
  • On turning the ignition on, if you hear a clicking sound it can be a sign of a dead cell. The sounds occur because when the starter solenoid coil receives insufficient current from the battery (to start the engine), it produces a clicking sound which tells you what a dead battery sounds like.
  • A slowly cranking engine might also be a sign of a bad battery. In this case, the engine will crank slower than usual when you turn on the ignition.
  • A corroded negative terminal is usually caused by undercharging. A continuously undercharged battery can lead to a dead battery.
  • If your car would not start unless you push the gas pedal to get it started, there is a chance the car battery has gone bad.
  • In case your car engine stops working out of nowhere but starts to work after some time, it means that there is an issue with the battery.

How to Test a Car Battery for a Dead Cell?

A dead car battery can be identified easily with the above-mentioned symptoms. Nonetheless, if you want to test the battery of a car for a dead cell, then allow me to tell you some ways that you can rely on:

Physical Inspection

During the physical inspection, you need to look for car battery cell damage. Physical inspection may include broken terminals, a bump or bulge in the case, cracked or ruptured plastic, discoloration, or excessive leaking.

Electrolyte Specific Gravity

Check for the specific gravity of the electrolyte fluid to test one dead cell of the car battery. The specific gravity is the ratio of water to the electrolyte fluid. Ideally, the specific gravity of the electrolyte is 1.26. If it is lower in one cell than others, it might have gone bad.
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Voltage Reading

Another way to check the state of the battery is the voltage reading. For this, you will be needing a multimeter and know-how of different states of voltage. To ease this process for you, I have mentioned below some voltages and what they represent.

  • 12.4-12.7V is the ideal reading for a battery that is in a good state.
  • Any reading below 12.4V is an indication that the battery needs tickle charging.
  • In case the multimeter reads a voltage higher than 12.7V, the battery needs to release some charge.
  • A 0V reading shows the battery has a short circuit.
  • If the battery has a dead cell, the reading would max out at 10.5V and would not go higher than that.
  • If a fully charged battery (according to its charger) and the voltage remains 12.4 or less, the battery is sulfated.
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What Causes a Dead Cell in a Car Battery?

There are various reasons that cause a dead cell car battery. Whatever the reason is, a dead car battery needs to be replaced as soon as possible. Here are some reasons that lead to the cells of the car battery to run out.


Car batteries use Sulfuric acid as their electrolyte. When the battery starts to function (electrolysis) the electrolyte splits up and forms free sulfate ions. These sulfate crystals stick to the lead plates of the battery forming a compound known as lead sulfate (crystals). Over time these crystals keep on depositing resulting in a hardened covering over the entire plate. The longer the battery sits without being recharged, the more sulfate will develop.

Age of the Battery

A battery cell is composed of electrodes. The cell runs out of its chemicals over time and becomes unable to sustain reactions. Old cells also tend to get an internal short or open where the electrode structure goes bad from aging due to erosion.


Quite obviously, corrosion can lead to a dead cell. I have noticed that overcharging/undercharging does not only corrode the battery terminals but also decreases the life of the battery overall. When paired with aging, corrosion can be quite destructive for the battery.

Electronic Parasites

Bad alternators, low-quality cables, damaged fuse, loose terminals, etc. are considered as electronic parasites as they contribute significantly to killing your car battery.

How to Fix a Dead Cell in a Car Battery?

On identifying a dead cell in your car battery (or in case of a whole dead battery), you should immediately replace it with a new one. However, there are certain ways to fix dead car battery cell. Following is a step-by-step guide that will help you:

  • First, you need to locate the dead cell in your battery with the help of a specific gravity tester. The ideal specific gravity is 1.26. If it reads more or less than that, it means that the cell is dead. A rule of thumb is that there should not be a difference greater than 0.05 between each cell reading.
  • Once you have located the dead cell, cut the battery top and remove it.
  • Wash the removed cell chamber with a solution of baking soda in water to remove any dirt or deposits accumulated on it.
  • Now place a separator between the positive and negative plates to make the cell out of it.
  • To make the terminals of the cell, use molten old lead plates.
  • Weld the terminals of the cell to the terminal of the battery.
  • Fill in the 1.26 specific gravity electrolyte.
  • Finally, recharge the battery for at least 12 hours then are ready to go. For Video Click Here.

Here comes a question. Does dead car battery recharge itself? Remember that a battery, dead, or working cannot charge itself. Using a dead car battery is quite hazardous, so I would suggest quitting its use unless you like trouble.

How to Charge a Dead Car Battery at Home?


If your car battery has run out and you cannot find a workshop to get it recharged, do not worry as you can easily do it at home. You will be needing only 3 things: Safety rubber gloves, battery charger, and wrench.

Safety first! Wear rubber gloves and make sure the working space is free of moisture. Start by removing the negative terminal with the help of a wrench. Then remove the positive. Once they are disconnected, attach the charger’s black wire to the negative terminal and red wire to the positive terminal of the battery. For the user’s ease, the nature of terminals is mentioned on the battery. Set the charging current by keeping in mind the battery’s capacity. It should not be more than 10% of the battery’s capacity. After setting everything up, plug in the switch, and begin the charging. Looking for a Fully-Automatic Smart Charger? Check out the latest price. 

I know what are you thinking now. Does charging a dead car battery work? Well. It all depends on the condition of your battery cell. If it has not aged that much and is in good condition, it will most definitely work.

How to Change a Dead Car Battery?

Using a dead car battery is not only hazardous but can also affect your car in all sorts of negative ways. It is best to replace it in time. Here is a guide to changing a dead battery which makes the process easy as well as faster.

Open the bonnet and locate the battery. Now remove the battery clamps (first the negative, then the positive one). The sequence of removing and attaching the terminals is important so never forget it.

Pull out the battery from its tray. Before placing the new battery in, clean the cable connectors with a hard bristle or a wire brush and then place it in the new battery.

Make sure it lays perfectly on the tray. Reattach the terminals (positive first, then negative) Fasten the battery with the clamps.

Another great way of getting rid of the old battery is to exchange it from Walmart as Walmart takes dead car batteries and offers discounts on core charge fees on purchasing a new car battery.

Does a Dead Car Battery Affect Key Fob?

The key fob of the car works on the battery. So, if you ask me if the car battery goes bad, would it make any difference for the key fob? The answer is yes.