The Battery Charger Won’t Charge A Dead Battery

The battery charger won’t charge a dead battery. At least once in your life, you’ve gone through the experience of your car not running because of the battery.

To avoid this, you decide to get yourself a smart battery charger. 

However, even after getting a charger, you notice the battery charger won’t charge a dead battery.

 The article below will help you understand how to handle such a situation.

Can A Completely Dead Battery Be Recharged?

When people refer to their car battery as dead, they usually mean that the battery is discharged and its voltage level is below the functional level. 

Your car battery needs to run around 12 or more volts to function properly.

Therefore, if your battery level drops below 12V, it may be a dead battery. Generally speaking, you have three ways to solve the problem.

Alternator charging

If your battery’s voltage is a bit lower than the bare minimum, there’s a simple solution to your problem. 

For your car to run, it needs power from the battery, and your battery needs an alternator to recharge it. 

The alternator powers the battery for its next start, but only when the car is in motion. 

Therefore, fixing a battery that has dropped its voltage a bit too low and driving around could be the solution. 

Also, while attempting to recharge your battery by driving around, it’s best to avoid using any features that require power from the battery, such as the AC, TV, radio, etc. 

Driving around for roughly half an hour could be enough to recharge your battery to a functional level. 

However, this way won’t always fix the problem if your battery level is extremely low.

Jump-start your car

If your car doesn’t even start when you turn on the ignition key, you could face a dead battery. 

Therefore, to fix this problem, you’ll need to jump-start your vehicle. To jump-start your car, you’ll need jumper cables and another car. 

Following the appropriate safety precautions, connect one end of the jumper cables to your car’s battery and the other end to the other car. 

With the other car running, its alternator will power your car’s battery and following a few minutes, your battery will have enough power to run your car. 

Of course, if you are near a charging station/wall socket, you can recharge the battery with a smart charger.

Jumper Cables

Caption: Jumper Cables

The Battery Charger Won’t Charge A Dead Battery: The Battery Charger Won’t Charge A Dead Battery

Some people have faced situations where their smart charger doesn’t recognize a battery because it’s too discharged. 

Remember that a 12V battery is discharged at 11.9V and fully charged at 12.7V.

However, if left discharged for long periods, a battery can draw a lower power level, thus affecting the battery’s health and, in the worst case damaging the battery entirely.

Float chargers and battery maintainers normally have a voltage threshold between 8 and 11, while some chargers’ voltage threshold is relatively high. 

Therefore, if your battery has lower power, the charger may not recognize the battery, and it won’t send a charge.

 Some chargers might display a fault mode by flashing, and others simply do nothing.

 Several manufacturers don’t think charging a battery below their charger’s threshold voltage is worth charging.

Also, some marine battery chargers can determine the battery’s voltage before sending any current to prevent sparks in case you didn’t connect the charger to a battery.

Furthermore, smart chargers having a minimum threshold voltage can prevent the charger from damage. 

However, it can be a pain when your charger doesn’t charge your legitimate battery because it’s too low on power.

How To Make A Smart Charger Recognize A Dead Battery

To fix the problem, first, verify that your battery has sufficient electrolytes to cover the lead plates. 

Next, ensure your charger is making the proper connection by ensuring no dirt build-up or corroded terminals could hinder the connection.

If you have a flooded battery with a removable cap exposing the fill holes for each cell, cover the lead plates with enough liquid. 

You can add distilled water till you slightly cover the lead plates. It’s best to use a syringe to avoid any accidental spills. 

After that, you’ll need to refill the battery cells and hook up the battery to your smart charger. 

Also, use a wire brush to remove any form of corrosion. If you encounter some tough corrosion, you can use water or baking soda paste to get the job done.

The next step is to give your battery an artificial or temporary surface charge using another battery. 

You’ll need jumper cables and a car with a functioning battery. 

If you have a 12V battery and the opposite battery is a 12V one, then you can set up the jumper cables as if you were charging another battery. 

While the car is on, connect one end of the positive jumper cable to one battery and the other end to the other battery.

 Repeat the same for the negative ends. Give the battery about 2 minutes to charge and detach the jumper cables in reverse order of how you made the connection.

Lastly, hook up your battery to your smart charger, which should have enough artificial surface charge to trick the charger to begin charging the battery.

 If you fail first, you should try running the entire process again. Remember to never leave your dead battery connected to another battery for too long.

Car Battery Connection

Caption: Car Battery Connection

What Would Cause A Battery To Not Keep A Surface Charge?

If you have shorted out or bad cells in your battery, it might be time to forget about it. 

A bad cell in the battery means your charge needs to work extra hard to charge it if it even manages to recognize the battery.

Therefore, the charger will strive to bring the remaining good cells to a higher voltage than normal to compensate for the bad cells.

Since the good cells carry a higher voltage than normal, they’re overcharged and evaporate the water exposing the lead plates and causing them to short out and sulfate.

 All it takes to kill your battery is one sulfated or shorted cell. A dead cell causes damage to the other cells during the charging process. 

You can use a hydrometer to test each cell in a flooded battery.

On the other hand, sealed batteries can handle low levels of overcharging and recycle the evaporated water to the electrolyte. 

If you ever charge for too long, you’ll be unable to replace the water lost as the battery vents out the pressure to avoid structural damage.

How Do I Know When My Car Battery Is Fully Charged?

You can use a voltmeter to determine the charge level of your battery. Thankfully, every battery box comes with a voltmeter. 

All you need to do is connect the battery to the voltmeter to determine its voltage. 

Below is a voltage chart for charge levels ideal for AGM and deep cycle batteries.

Level of ChargeVoltage


As mentioned earlier, some chargers fail to recognize a battery that’s extremely discharged to prevent damaging the charger if there’s no battery connected. 

For all your battery charger cable needs, contact Cloom Tech.