If you ever have trouble starting your car, chances are, you have a dead car battery that you’ll need to revive.
A battery is one of the most important parts of your vehicle. It’s responsible for sending power from the starter motor to the spark plugs.
When it fails, the spark plugs cannot ignite the fuel. Your other car systems such as lights, air conditioning, and radio will also not turn on.
It’s always best to attend to a troublesome battery immediately. This could be by trying to revive a dead car battery or reconditioning one. If left unattended, it could lead to other problems in the long run such as a damaged alternator.
Fortunately, it’s not something that should cause you to worry. It’s one of those car problems that we talked about that you can easily fix by yourself.
Wondering how to bring your dead car battery back to life?
Below are a couple of simple solutions that will see you revive your dead car battery in no time.
You can use the table of contents below to navigate through this post.
How to revive a dead car battery
There are basically three things that will cause your battery to die: human error, issues with the electrical system, and battery problems. Here’s how to fix each of these.
1. Human error
Human error includes:
- Leaving your headlights, interior lights, the radio, glove box, and signal lights on when the car is off – drains your battery.
- Not starting the car for a very long time which causes the battery to discharge completely while trying to keep some electrical systems alive.
- Using the air conditioner while the car is not running – drains your battery.
- Leaving your door(s) or trunk/boot open – drains your battery.
- Frequent short drives that give the alternator little time to recharge the battery, etc.
A lot of new cars alert owners when they’ve left their car in some of these conditions.
But just in case yours doesn’t and you wake up to a dead battery, grab your jumper cables, or borrow some from a good neighbor.
It’s time to try the first solution which is jump-starting your car.
How to jump-start your car
Step 1: If you have a scarf, tie or jewelry, take them off. Put out any cigarettes before getting down to business. Once done, drive both cars close to each other and take out your jumper cables.
Step 2: Put both vehicles in Neutral or Park, and switch the ignitions off. Engage both parking brakes as well and open the hood/bonnet on both cars.
Step 3: Attach one end of the red cable to the positive terminal of the dead battery and the other end to the positive terminal of the good battery.
Step 4: Attach one end of the black cable to the negative terminal of the good battery and ground the other end to an unpainted metal surface. You can attach it to a bracket or a bolt on the engine, away from anything flammable.
The reason why we are not attaching the second end of the black cable to the negative terminal of the dead battery is because this can cause sparks that can lead to an explosion.
Step 5: Turn on the good car and let it run for a couple of minutes.
Step 6: Try to turn on the car with the dead battery. If it doesn’t turn on, give it another 5 minutes before trying again.
Step 7: If it starts, don’t switch it off. Drive it for at least 15 minutes to rejuvenate the battery. This allows the alternator to recharge it.
2. Electrical system problems
Electrical problems on a battery can be caused by:
- Faulty or loose wiring
- Corrosion
- Poor installation
- Defective fuses
- Faulty charging system
These can also cause parasitic drains or even prevent the starter motor from drawing power from the battery to send to the the spark plugs.
How to fix electrical system problems to revive a dead car battery
a) Check for corrosion
This manifests as green, blue, or white material on the battery connectors, cables, or terminals.
It can be cleaned off using a dry rag, sandpaper, or a stiff-bristled wire brush. In severe cases, you can use a mixture of baking soda and water.
Avoid getting the mixture on the battery cells or floor of your garage. It could leave stains that can be hard to clean.
b) Check for loose connections
Follow your wiring and ground cables that connect to the fuse box, starter, junction block, and car frame. Make sure they are all connected tightly. Check also that your battery doesn’t have a loose terminal clamp. If it does, here’s how to tighten your battery terminals.
c) Test for current flow
You can use a multimeter or test light to check for current flow. In the case of a multimeter, set it to the highest amperage to avoid blowing the fuse inside.
Disconnect a battery cable and complete the circuit using the multimeter when using it. The average 12-volt car battery comes with a capacity of 48Ah.
If you’re using a test light, disconnect the negative battery terminal and complete the circuit with the test light. If the light illuminates, you have a drain in your system. Take out your jumper cables and follow the steps highlighted earlier to jump-start your car.
d) Track your parasitic drain
Identifying electronic components that may be faulty or connected wrongly can be time-consuming. One of the best ways to locate them is by removing individual fuses at a time while the multimeter or test light is connected.
Once you locate the fuse, follow through to identify the corresponding circuit. This will help you find the faulty component.
If it’s a component you can easily repair or replace yourself, go ahead and get a replacement. However, if it’s something you’re not familiar with, reach out to a mechanic.
e) Check for loose or worn alternator belts
Belts and tensioners that are stretched or worn out can affect the ability of the alternator to charge the battery. This may cause your car to die often. Tighten your belt and tensioners, or replace them if they are worn out.
3. Battery problems
Battery problems mainly arise due to:
- Hot or cold weather
- Old battery
- Weak battery
- Sulfation
These problems can cause the untimely death of a car battery or cause it not to hold charge. They may also reduce its lifespan.
The solutions provided below will help you prevent such untimely deaths, keep your battery in check, and in some cases, make a dead battery work again.
How to fix battery problems
a) Check the electrolyte level often
The electrolyte is a solution of water and sulfuric acid. It should always submerge the lead plates in all cells. Exposure of the plates to air causes them to sulfate and become inactive.
Always add enough distilled or de-ionized water to cover the plates up to the right level. You should never add acid as this may cause excessive corrosion or raise the specific gravity way too high.
Note: In “Maintenance Free” batteries such as the one shown above, manufacturers do not provide means for maintaining the water/acid level in the battery, meaning that you’ll have to buy another unit if yours runs dry.
b) Check the specific gravity
You can use a hydrometer to check the specific gravity of the electrolyte. Specific gravity is the ratio of the density of a liquid. In a fully charged battery, it should be between 1.265 and 1.300.
If you find out that the specific gravity of your battery is 10 points higher, remove some of the electrolyte and add some water. If it’s lower, add some sulfuric acid or a solution of Epsom salt (Magnesium Sulfate) to raise the gravity. Dissolve Epsom salt (MgSO4) in water in the ration of 1:3.
Aspirin (acetylsalicylic acid or C9H8O4) has also been known to alter the electrolyte mix. Add 12 Aspirin tablets (325mg-500mg) into about 6 ounces of water.
c) Park your car in a parking garage or carport
Avoid leaving your car in extreme hot or cold weather all the time. This is because the extreme temperatures can sometimes cause lead sulfate crystals to accumulate.
The crystals shorten the lifespan of a battery. They could also magnify already existing problems that may make it hard to revive a dead car battery.
d) Buy a battery tender/maintainer
If you’re going to leave your car unattended for a long period of time, a battery tender helps to keep it charged and operational.
This ensures that it does not completely drain while trying to keep some electrical components alive. It also means that you will not have to revive your dead car battery when you come back.
The best battery tenders monitor how much charge a battery needs and charge it slowly over several hours. They also extend the lifespan of a battery by preventing lead sulfate from forming on the electrodes.
e) Get a battery charger
Battery chargers help to recharge a battery that is low on power. This helps to prevent unwanted failure or sulfation immediately after use.
You can also get a battery booster pack. This is a device used to safely restore a battery to the needed charge. It can also be used as a battery jump starter for jump-starting your car.
How to recondition a dead car battery
You may have seen a shop that buys dead car batteries. If you haven’t, here’s how it works.
Such shops recondition old dead batteries and resell them at about 80% of the original price. With the average battery costing between $100 and $300, it’s a pretty cool business.
The shops normally have professionals that have considerable experience with refurbishing old batteries. The most interesting thing is that, these batteries can be used for another 5 years.
Battery reconditioning is something you can do by yourself. It not only keeps your battery alive, but also saves you money that you could have used to purchase a new one.
Just remember to first check the voltage of your battery before you get down to business. Only recondition a battery that has a voltage of not less than 10V.
Here’s what you’ll need:
- Goggles to protect your eyes from acid
- Chemical-resistant gloves to protect your hands from acid burns
- Protective apron
- Battery charger (the slow trickle type)
- Screwdriver
- Voltmeter
- Plastic funnel (avoid metallic funnels as they can react with the acid)
- A bucket of distilled water
- Two plastic buckets
- 450g (1 lb) of Epsom salt (Magnesium Sulfate)
- 450g (1 lb) baking soda
- Wire brush/tooth brush
How to recondition a car battery at home
Step 1: Put on your protective gear
Battery acid is dangerous. It can burn your hands and spill on your eyes. Start by wearing your gloves, goggles, and protective apron for safety. Cover any exposed areas that may be prone to getting into contact with the acid.
Step 2: Get to a ventilated area
Look for a well-ventilated area that you can work at. It should be away from any sources of fire since battery acids are flammable. If you can avoid hot locations and direct sunlight, the better.
Step 3: Clean the battery
Before you start working on your battery, make sure that the terminals are not contaminated or corroded. Dissolve some baking soda into clean water until you have a runny paste. Use this to remove any corrosion with a wire brush or tooth brush. Allow the terminals to dry.
Step 4: Make your own electrolyte
You’ll use Epsom salt and boiled water to make your own electrolyte. How much Epsom salt do you use in a battery?
Boil about 2 liters (half a gallon) of distilled water and pour in 225g (half a pound) of Epsom salt. Stir the mixture well until the salt is completely dissolved. Alternatively, you can buy battery acid from your nearest auto shop.
Don’t rejuvenate car battery with vinegar. Vinegar is harmful to batteries. It is mostly water and about 5% acid. It reduces battery endurance, performance, and life expectancy. It also damages the lead plates and voids any existing warranties in new batteries.
Step 5: Remove the cell caps
Use your flat-head screwdriver to pry off the caps that cover the cells. If they can be unscrewed, unscrew them. In some batteries, you may have to remove a top cover first before accessing the caps that seal the cells.
Step 6: Empty your battery
Grab one of your plastic buckets and pour into it the battery contents. Do this carefully and slowly as you direct the battery cells away from you. Once done, put the battery down facing upwards and keep the bucket away for safety.
Step 7: Clean the cells
Mix a solution of 225g (half a pound) of baking soda into 2 liters (half a gallon) of water. Use the plastic funnel to fill the battery cells with this solution. Put the cell caps back on.
You’ll need to shake the battery for two minutes. However, batteries are heavy, and as such, you can shake yours while taking short breaks. Once you’re done, empty the solution into the same bucket you did the battery contents.
Step 8: Pour in your electrolyte
Clean your funnel to remove any traces of the baking soda solution. Use it to pour into the battery cells the electrolyte you prepared in step 4 above. Or, if you bought battery acid, use it.
The lead plates should be immersed. Any remaining electrolyte can be bottled and saved.
Step 9: Charge your battery
It’s time to charge your reconditioned battery. You may need to do this without the cell caps on. This is because charging produces gas that can build up and cause the battery to explode.
Connect the battery to your battery charger starting with the positive terminal. Make sure the charger is a slow trickle charger, and not the rapid charging type. Let the battery charge for 36 hours.
Step 10: Test your battery
Test the battery with your voltmeter. It should read 12.43 Volts or more. But, don’t worry if it’s a bit less than that.
A few experts recommend charging the battery for another 12 hours. Once done, re-install your battery in the car. Make sure all the cable connections are done right and tight.
Before firing your engine, turn your headlights on for a few minutes. Check your battery again with the voltmeter. If it reads below 9.6V, you can recharge or cycle it.
Step 11: How to cycle your battery
Here’s how to cycle your battery. Leave your headlights on for a while to fully discharge the battery. Remove the battery, then recharge it. Repeat this process until you get a 9.6V reading on your voltmeter.
Final Note
The steps and tips provided in this article are pretty simple to follow. With extra care and self-belief, you can be your own personal mechanic for such minor car problems.
For the battery, I’ll leave you with a few caveats below that will ensure you’re successful when handling it:
- Always try and give your car battery a break. Avoid overloading it by unplugging charging cables and electronics that are not in use.
- Switch your interior and exterior lights off at all times when you get out of the car.
- For serious electrical problems that you can’t trace, always get a skilled mechanic to check it out for you.
- Keep an eye on your battery to identify signs of defects and aging. You can look out for clicking engine sounds and the dimming of lights.
- You should typically replace your car battery every 3-4 years. In the best-case scenario, your battery can last up to 7 years.
- Invest in a battery fender/maintainer if you’re not going to use your car for a very long time or if you live in an area with extreme temperatures.
- Always keep your battery well-maintained and in good working order. Test it often and address issues as soon as you can to maintain its lifespan.
- Always have a jump-starter pack in your car. You can keep your jumper cables in a cable bag in your boot/trunk.
- Lead-acid batteries weigh a lot. Aways protect your back when moving yours around.
- Only use a compatible charger when recharging a reconditioned battery. Never overcharge it.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in technical matters.
