3 Ways To Tell If A Battery Is Bad

Batteries are among the greatest feats that humans have ever developed. Through these batteries, machines and equipment can operate without being plugged into an electrical outlet. 

Numerous types of batteries exist today. Some are used for simple household stuff, like radios and remotes. Others are being used to power electric vehicles. Meanwhile, some batteries are equipped in complex systems such as portable power stations. The Power Station 300Wh from Sunly Power is an example of these portable charging devices. 

But keep in mind that not all batteries are the same. And not all the time, they are in good condition. Batteries can go awry, too. So it is essential that you know how to identify whether or not your batteries are bad or about to fail. 

How To Tell If A Battery Is Bad


Before anything else, you should know that batteries don’t work like water bottles. It is incorrect that you drain half of its capacity now and save the rest later. You won’t optimize their performance if that’s the case. Moreover, doing so could deteriorate their lifespan. In fact, lithium batteries go bad if not used

Furthermore, batteries don’t spill or leak power. That’s a typical misconception. If the batteries aren’t working the way they should, there’s a good chance that there are chemical problems within its system. 

Here are some of the tested-and-proven ways to test your batteries:

Inspecting The Battery

The physical appearance of the battery will immediately tell you if it is still in good condition. Some of the observable signs are the following:

  • Ruptures and cracks on the container or shell
  • Liquid or fluid leaking
  • Battery case has bumps or bulges
  • Terminals are damaged or broken
  • Notable discolorations

When the terminals are loose or damaged, the battery is prone to short-circuiting. And that’s quite dangerous. After all, short circuits are then followed by melting or burning. In some cases, explosions could take place since short circuits cause the battery to unload its entire power all at once. 

If the battery’s case has bulges on them, that’s a sign that it is a victim or overcharging. In some cases, damaged cases are due to improper handling of the battery. The presence of cracks and holes doesn’t mean that the battery will not work. But for safety precautions, you should just replace the damaged battery with a new one. 

Flooded or wet-cell batteries require the appropriate water levels to be kept. If the water is low, distilled water can help out. However, if the cells of these batteries have been exposed to the elements for prolonged periods, you need to replace the battery. Otherwise, sulfation could take place. This is the process that causes the battery to cease its chemical functions. 

When charging wet cell batteries, it is important that you check their water levels first. If you charge the battery while it is dried, there’s a good chance that it could burn. If the battery has plenty of liquid, but its color is dark, it is a sign that the battery is already bad. 

Even just a single brown cell indicates that the battery may not work entirely. Of course, the solution to this problem is to swap the battery with a new one. For instance, you can replace a lead acid battery with LiFePO4 for a more efficient power source. 

Checking The Voltage Reading

One of the best ways to test the health of the battery is to check its state of charge. You can do this by doing a voltage reading to the battery. 

Below indicates the stage of charge of batteries and their corresponding voltage. 

State of Charge 

  • 100 percent – 12.7 to 13.2 volts
  • 75 percent – 12.4 volts
  • 50 percent – 12.1 volts
  • 25 percent – 11.7 volts
  • Discharged – 0 – 11.6 volts

If the voltage reading is 0 volts, there’s a big probability that the battery experienced a short circuit. 

If the voltage reading is no less than 10.5 volts when being charged, it has a dead cell.

If the battery is fully charged, but the voltage doesn’t reach 12.4 volts, its battery is probably sulfated. 

Sulfation is the residue every time the battery discharges. So technically speaking, recharging the battery will reverse the sulfation process. The crystals would return to their original crystal form, which, in turn, would allow them to generate power. 

However, if the battery is uncharged, badly discharged, drained for prolonged periods, or saturated, sulfation would take place. It will become big and hard, eventually covering the plates. Once the plates are full of sulfation, the chemicals required to generate power are stripped. 

Furthermore, sulfation reduces the ability of the battery to reach its full charge. At the same time, it causes the battery to drain faster than usual. If you charge a sulfated battery, it is like washing your feet while wearing boots–there’s no point! So instead of recharging the battery, you simply have to replace it. 



Your nearest automotive shop is capable of load-testing your battery. But you can do this process on your own with the use of digital voltmeters. To attain accuracy in a load test, you need to fully charge a battery first. After that, leave it for around 12 hours before you load-test it.

A newly charged battery contains the residual charge of the charger you used. Hence, if you let the battery lay dormant for 12 hours, the residual charge will be released. At this point, the battery is already in its pure form. It will work the way it is expected to. 

Let’s take a vehicle battery as an example. 

  • To load-test the battery, expose it from its battery container until such time you have access to its terminal. But in doing so, make sure that you don’t remove the battery from the vehicle. Otherwise, you will never be able to test it. 
  • Next, get the prongs of the voltmeter and attach them to the appropriate terminals of the battery. 
  • After that, start the engine of your vehicle and see where the voltage drop is. But even if the vehicle doesn’t start, as long as there’s a voltage reading, the process is successful. 

For a 12-volt battery, the healthy voltage is 9.6 to 10.5 volts under load. It should also maintain the said voltage for at least 30 seconds. 

A discharged battery is when you start the engine, and the volt meter drops to the ideal voltage range. However, if the starting load drops below the ideal volt range, even under the starting load, the battery is supposed to be dead and must be replaced. 

Final Thoughts

Overall, there are three methods of assessing the health of the battery, and that is through checking its appearance, checking its voltage reading, and load-testing it. These are simple yet efficient methods that would let you know if your current battery requires replacement already.