How To Tell if Deep Cycle Battery is Bad

How to Tell if Deep Cycle Battery is Bad

Are you experiencing trouble in the functioning of your deep cycle battery? If yes, then you must check whether your battery is bad, damaged, or dead. You can either hire a professional’s assistance or simply carry out a series of tests to clear the doubt if the deep cycle battery is bad or not.

This encompasses a thorough physical inspection both of interior as well as exterior parts, voltage test, and loading test. Once these steps are carefully undertaken, you will get a clear insight into the battery so that you can either change the battery or employ maintenance practices.

Below are some of the ways that will ensure the optimum performance of the battery and eliminate the need for running a bad battery.

3 Steps That Precisely Tell if Your Deep Cycle Battery is Bad

Physical Inspection

To confirm the bad status of your deep cycle battery, the first and foremost step is to conduct its physical inspection. Starting with the exterior parts, check the terminals of the battery.

If they are broken or loose, a short circuit may occur. In the case of the battery’s short circuit, all the power gets unloaded and burning and melting start occurring. Thus, soon the battery will explode.

Physical Inspection

Secondly, if there is a bulge in the battery’s case; this implies that the battery is overcharged. This can affect the lifespan of the battery. Other signs indicating that the battery is bad are cracks, leakage, holes, and discoloration on the exterior part of the battery.

Lack of water in the battery for a long time can also pose threats and severely damage the battery making it highly unsafe to use.

Voltage Reading

Voltage Reading

The next step is to carry out the voltage test to check how much your battery has the voltage so that it can deliver enough power. Before carrying out the voltage test, fully charge the battery.

Digital multimeter and voltmeter are undoubtedly the specially designed devices used for carrying out a voltage test in an impeccable manner. The reading on the device will tell if your deep cycle battery is bad or good.

For an instance, if the voltage reading is 0, it infers that the battery has experienced a short circuit and is dead.

If the voltage can’t cross 10.5 volts, it implies that the battery has a dead cell and it needs to be replaced. On the other hand, if the battery is fully charged and still the voltage rating comes out to be less than 12.4, it means that the battery is sulfated.

Loading Test

The final step involves carrying out the loading test to know whether the battery can deliver enough power without fluctuations or not.

Take the battery and connect the prongs of the voltmeter or any other testing device with the correct terminals on the battery. Push the start button and check the reading on the voltmeter.

If you notice that your battery began to hold and then steadily dropped in voltage, then unquestionably your battery is bad.

Loading Test

Also, if the voltage reading dropped to 0, it is too a sign of a bad battery. A battery is good only if its 12-volt rating shows a consistent reading between 9.5 volts to 10.5 volts range.


The entire process encompassing the three steps is quite time-consuming and involves immense efforts and patience, but the desired results are guaranteed. By clearly performing the aforementioned three steps, you can get a clear idea whether your deep cycle battery is bad or good and you can troubleshoot your battery issues. In addition to this, rectifying these problematic areas will also eliminate the erratic performance of your battery and make it efficient once again.


How Can We Troubleshoot Bad Deep Cycle Battery Issues?

If you are to troubleshoot the bad deep cycle battery issues yourself, you can carry out a ‘deep discharge’ test which can be done with specialist discharge testing machines.

Secondly, you can conduct a physical inspection test and check the presence of cracks, leakage, holes, or any discoloration on the exterior part of the battery. Besides these, you can conduct a voltage test and loading test with the aid of multimeter, voltmeter, or wattmeter.

How Long Can A Deep Cycle Battery Hold It’s Charge?

Usually, if you employ proper care and maintenance practices, your deep cycle battery can last for approximately 6 years. It will hold up the charge for an extended period of time if a good and specific charger is used for charging the battery.

How Can We Extend The Deep Cycle Battery Life?

Here are simple ways which if employed can extend your deep cycle battery life.

  • Give your battery a chance to fully charge in a complete cycle each day.

  • Fully charge the battery before you place it in the storage.

  • Another way to extend the battery life is by making sure to charge the battery as slowly as possible.