Dead Car Battery: Signs and Fixes


Oct 30th, 2019

Dead Car Battery: Signs and Fixes

Although a car runs on fuel, the battery is the component that starts up the engine and many other systems of your vehicle. Of course, a little help comes from the alternator to ensure your car battery is fully charged or at a charge level that can handle the power requirements of your car.

The last fix you want to be caught up in is your car battery failing or dying on you. 

Most people don’t know how long a car battery should last. Therefore, they get caught unawares in a dying car battery fix. A fairly managed car battery can last between 5 to 6 years whereas a well-managed and never deep-cycled battery can last for over seven years. Cheap car batteries such as lead-acid batteries may last shorter than that.

It is important to note that the year-round climate and driving distance also affects your battery’s life span.

Lucky for you, some signs can tell when you have a dead car battery or at least a dying one. Not only will you be able to tell when it’s time to get your battery checked, but you can also get yourself out of a tricky situation with some tips that we’re sharing with you in this article.

Signs of a Dead car battery

There's no surer way to ruin a weekend drive than a dead car battery or one about to die. Fortunately, various telltale signs will give you a good idea that you are dealing with a dead car battery.

  1. No dome light or door chime

A weak battery will show a dim dome light, but with a dead car battery, there won’t be a dome light at all. If you fix your battery and still see no dome light, consider having your door wiring checked. 

  1. Dim headlights 

The battery usually powers the lights of your car. If you notice that your headlights are dim even when you accelerate, then chances are your battery is dead and, ergo, cannot supply the required power. Additionally, your car radio and air conditioner may fail to turn on.

  1. The engine won't start when you turn the ignition key

A dead car battery will not be able to generate the spark required in engine combustion. As such, you won't feel anything when you turn the ignition key.

In other cases, you can feel the starter motor running but not the engine. The starter motor may sound laboured or crank slowly. 

A faulty starter and worn out spark plugs can cause the crank engine to start sluggishly. Eliminate this possibility first before you can single out the dead battery as the issue.

  1. Engine light

Many things could make the engine light turn on, including a dead car battery. As good practice, check your battery voltage to ascertain the issue. If the voltage meter displays a number below the expected reading (10.5), then you have a dying car battery.

  1. Backfiring 

Although backfiring can be caused by other factors, it is worth checking out the battery. The battery can produce desultory sparks which will cause incomplete combustion in the engine. The resultant effect is fuel accumulated in the combustion chamber and later passed along the exhaustion chambers.

What happens chemically when the car battery 'dies’?

A 'dead' battery may refer to different cases but generally means that it can no longer deliver enough power or hold a charge. The usual cause of getting a battery killed is sulfation. 

To understand the chemistry behind a dead car battery, we have to know the basic components of a car battery. A car battery has alternating plates and an electrolyte. The plates are usually of dissimilar metal elements, like lead and lead oxide (Pb and PbO2). The commonly used electrolyte is sulphuric acid (H2SO4).

During the discharging process, electrons flow from the lead plate to the lead oxide plate, resulting in the generation of electric current to supply the power requirements of the systems. Due to the chemical reaction, the plates become chemically similar.

In other words, 'soft' sulphation occurs during the discharging process. However, due to immediate recharge when the car is running, a reverse chemical reaction takes place, which results in the plates becoming dissimilar again: lead and lead oxide. The number of charging/discharging cycles is limited since the average car battery only lasts for 5 to 7 years. 

Factors such as leaving the battery discharged for a long time causes 'hard' sulphation, which happens when lead sulphate crystals form and progressively cover the chemical reaction area. This crystal formation, in effect, decreases the surface area available for chemical reaction and thus lowers the charging and discharging capacity of the battery. 

Continued formation of these lead sulphate crystals causes a crack and short circuits within your car battery and eventually 'killing' it.

How to revive a dead car battery

You can't save a dead battery, but there are ways to help you get it back to function a little bit longer. Here are some tricks to squeeze more life out of your battery:

  1. Jumpstart

The most common way to jolt a dead car battery to life is jumpstarting it. However, repeated jumpstarts will eventually damage the battery. It will no longer charge fully, and even if it does, it will only hold the charge briefly. It would be an intelligent decision to replace it at this point as it's useless to continue using it longer.

To jumpstart your battery, you will need jumper cables and another battery from another car. Warning: do not try this quick fix on a frozen battery because it can explode. Below are the steps to follow:

  • Pop up the hood of your car and locate the battery.
  • If your second battery is from another vehicle, have it parked by closely. Make sure that you have turned the car off before opening its hood.
  • Identify the terminals of both car batteries. The positive terminal is usually denoted by red while the negative terminal is black. 
  • Connect the dead battery and the donor battery using the jumper cables. 

Start by fastening the red clasp denoting positive onto the + terminal of the dead battery. Also, connect the other red clasp of the other end of the cable to the positive (+) terminal of the donor car battery.

Next, fasten the cable’s black clasp (-) onto the negative (-) terminal of the second car battery. 

Lastly, attach the black clasp (-) of the other end of the cable to the unpainted metallic engine block surface of the car with the dead battery.

  • Once you have connected everything securely, start the donor car. After a short while, start the vehicle with the dead battery.
  • In other cases, the car may fail to start after the first jumpstart. If that is so, wait for a few minutes and then repeat the previous step.
  • When the car starts, disconnect the jumper cables beginning with the negative terminals of the cable. Make sure the clamps make no contact while the cables are still connected to the car.
  • Drive your car for some distance to build up a charge which will ensure the battery doesn't die when you turn the vehicle off.

Jumpstart is only a quick fix, and you will need to replace the battery eventually. If the car doesn't start after jumpstarting, then call an expert to help out. 

  1. Using distilled water

If the electrolyte level falls, top it off using distilled water. Water will submerge the plates and create an additional reaction area that will allow the charging and discharging chemical reactions.

  1. Using an acidic solution

Adding a stronger acid to the electrolyte may help to restore chemical balance. Epsom salt (magnesium sulphate) can do the trick and deliver substantial charge to start the engine. Make a solution of Epson salt in a 1:3 ratio with water and add it to the electrolyte.

You can alternatively use aspirin since it contains acetylsalicylic acid. However, you’ll need about a dozen aspirin tablets (325-mg or 500-mg) and about 180 ml of warm water. Add the solution in equal amounts to each cell and use water to ensure the plates are covered.


Always make sure to use protective gear when carrying out these fixes to avoid harm from chemical spills. These are quick remedies to a dead car battery, and the only viable option will be to replace it with a new battery. For additional reading, refer to our guide to buying and replacing your car battery. 


Sam O.