At What Voltage Is a 12v Battery Dead?

Do you know when is a battery considered dead? Does your car battery just die on you for no apparent reason?

In this article, it will be explained what voltage ranges can batteries considered dead, analyze why sometimes batteries need a jump start and give some tips on what techniques can be done to extend the life of your current battery and avoid future mishaps. Let’s get started!

At what voltage is a 12 volt battery considered dead?

When the battery is dead, it can no longer produce any current. This doesn’t just mean that its charge has run out; instead, this means that there are not enough electrochemical reactions happening to allow a useful amount of electricity to flow through the circuit and power your device.

With the help of a voltmeter, a lead-acid battery, for example, is considered dead when the voltage falls below 10.7V or has no charge. When a lead-acid battery is “dead”, it cannot be given any more energy (this is called chemical exhaustion). Some lithium batteries may be considered dead at 9.4V and zero volt for NiCd, NiMH, and NiFe types.

A battery can become dead if it is left discharged for an extended period. This will cause the charge to be lost and, even after recharging, only a small quantity of stored energy remains.

How to tell if your battery is dead or just drained

A car battery can go dead from sitting too long without use, but it can also start to drain if you leave a light on or another item on. How do you know if your car battery is dead or just drained and needs to be charged? A voltage tester is an excellent way to measure how much power your battery has left in it. If it reads 0 volts, then your battery is fully discharged and will need to be charged before use.

A battery is considered “dead” when it has a voltage of zero volts. It’s important to note that this is different from a battery not being charged. A drained battery will have a voltage level of zero and will be unusable until it is recharged. However, a dead battery, which has been discharged, may still have some energy left for use.

Ways to prevent a dead battery from happening in the first place

Start by ensuring the battery is fully charged. To do this, you can keep your car’s headlights off for at least an hour after starting it or use a battery charger to charge it. In some cases, the battery may be defective and should be replaced.

Find out if your dome light is on in your vehicle or if you have any other accessories that are sucking power from the battery. This will let you to find out what drain is happening and stop it right away. You can also unplug electronics that are not being used.

If there is a drain and you’re not sure of its source, try using a voltmeter to measure voltage with each of the accessories plugged in. Close the switch on one and see if there is a change in the reading. If it changes, that means whatever has been left plugged in is drawing power.

If the battery is less than 12V, do not use it under any circumstances, as this will cause your car to break down or even catch fire. Worst of all, you may get injured while trying to start up a car with a dead battery.

Check your battery case for signs of maintenance. It should be in good shape and clean so that you can see how much power is left in it. Also, test the voltage to make sure it’s not running low or completely out of juice. If the cover is cracked, there’s a risk that acid may leak out, which can damage your car or even start a fire.

Regularly maintaining your car and caring for the battery case will decrease the chance of a dead or drained battery. A dead battery is not just inconvenient; it’s also dangerous because it can cause serious accidents if you’re forced to drive with one. If you have any questions about your car, ask a professional to inspect it for you if you are unaware of what the problem is and how to fix it.


Having dead batteries is no fun and can happen to the best of us at some point in our lives. If you’re stranded on one side of the road, it is essential to know if your battery is really dead or just needs charging. The process for determining which one you are dealing with starts by measuring the voltage of your car battery using a voltmeter.

To prevent a dead battery from happening is make sure to charge your vehicle every day. If in case you are driving an electric car and it won’t start because of a low battery, try plugging into another charging station or using jumper cables if you have them on hand. It can be helpful to keep jumper cables with you when traveling for emergencies like this one.

About the author, Phil Borges

Phil Borges is a battery aficionado. He's written extensively about batteries, and he loves nothing more than discussing the latest innovations in the industry. He has a deep understanding of how batteries work, and he's always on the lookout for new ways to improve their performance.