How to Test a Deep Cycle Battery?

How to Test a Deep Cycle Battery?

All cars and engines, for domestic and industrial purposes, need a good battery to work. Deep cycle batteries are one of the most reliable batteries in this regard but the key to enjoying durability, while using, is to know how to test a deep cycle battery. This will ensure it remains long-lasting and reliable. 

What is a Deep Cycle Battery?

The deep cycle battery is no more than a rechargeable lead battery that comes in variants, and may be used in many machines because of their energy retaining abilities. The term ‘deep cycle’ means the ability to work for a very long time. While other batteries are created for a short burst of energy, before they are required to be charged, a deep cycle battery may work to disburse up to eighty percent of its energy capacity before there is a need to recharge. Other batteries, with short burst energy capacity, often require a recharge as soon as they are below fifty percent.

Where a Deep Cycle Battery is Most Ideal?

Because of its nature, a deep cycle battery is most ideal for certain machines and in certain industries. Although, its domestic use is quite unlimited. For industries, the deep cycle batteries are most favored by heavy machinery in need of stronger batteries to operate such as the forklift and other machines involved in material handling.

Most of the standard equipment in the marine industry uses the deep cycle battery. This is because of the probability of long voyages or expedition which may require only the most sustainable batteries for all necessary equipment. Also, the deep cycle battery is used for recreational machinery like the golf carts and other recreational vehicles.

Because of its deep-cycle sustainability, it is very ideal for off-grid renewable energy such as the solar inverter installation for both domestic and industrial uses. Since most of the few examples listed here can be a huge machine to a rather handy one, one will not imagine having just the same form of deep cycle battery for all of these examples. This will bring us to the types of deep cycle batteries.

Types of Deep Cycle Batteries

Flooded Deep Cycle Batteries

This is also known as the wet cell battery. It is a wet cell or flooded because of the liquid that the battery contains. This liquid is an appropriately measured amount of liquid electrolytes inside the battery which is responsible for the general capacity of the battery.

Now, the wet cell battery or the flooded deep cycle batteries often seem convenient and cheap because after all, all that is needed to do is to ensure that this liquid electrolyte remains at the proper gauge. Sadly, this could be really difficult to keep up with. This is due to so many reasons such as extreme weather conditions, which may cause the liquid to evaporate, dry up or freeze, as well as a forceful movement that may cause the liquid to spill. Whichever case, the maintenance level for a flooded deep cycle battery is quite high.

Absorbed Glass Mat Battery/ Maintenance-Free Battery

This type of deep cycle battery does not need liquid electrolytes to function. This is because it uses a special type of mat to interact with the stored electrolytes when in use. You don’t have to deal with periodical changing of liquid electrolytes.

It is designed in such a way that the mat stays saturated with the right amount of electrolyte as it may keep the battery active for an estimated period of time. You will also not find any spilling liquid when the battery case is bad. Hence, you don’t have to deal with the effect weather condition has on the wet-cell battery.

Testing a Deep Cycle Battery

Flowing from above, you will realize that testing a deep cycle battery depends on the type of deep cycle battery you have. If you have an Absorbed Glass Mat battery, you will have to take keen care, right from the inception, by making sure that the battery is fully charged according to the number of hours indicated by the manufacturers.

After charging, make sure you balance the voltage by using your deep cycle battery for a short time. We often recommend about ten minutes of an average power-load on the battery. This will help stabilize the battery voltage level.

Furthermore, take note of the voltage rating as well as the ampere rating. Usually, a deep cycle battery comes in twelve volts but the ampere rating, also known as cold cranking amps may vary. For a wet cell battery, together with all of the above actions, you need to make sure that the liquid is well secured and not spilling, and also to constantly monitor the liquid electrolyte gauge.

Using the Multi-meter to Measure Voltage

Simply set your meter and place the positive, which is usually red, on the positive lead of your battery, and place the negative which is usually the black, on the negative lead on your battery. Since the right voltage of deep cycle batteries is 12V, it is acceptable if the meter reads between 12.6V to 12.8V. When the voltage of your battery is lower than this, i.e. 12.4 or lower, you may be needing a replacement soon enough.

In calculating the cold-cranking amps, take note of the CCA information on the battery and divide whatever number indicated by two. Place the meter points accurately on the leads for fifteen-minute. Your result should be within the range of your division and should the result be less than ten percent of your division then the load-test ampere measurement is low. Battery should be replaced.

Charging Right

Charging your batteries right is one of the best ways to keep your deep cycle battery active for a long time. The right charging should come in three stages. The first is the constant current which is simply an introductory boost. The second is the absorption stage where the battery self-regulate to a constant voltage. The last stage is the floating charge.

Monitoring your charging will help reduce the risk of under-charging or over-charging. For absorption charging keep your flooded battery at 14.4 to 14.8v while floating charge should be at 13.2 to 13.5v. while for absorbed glass mat batteries should be at 14.6 to 14.8v at absorption charge and 13.6 to 13.8v at a floating charge. Try to test the temperature while charging too. The standard temperature should be left at twenty-five degrees Celsius. You have to pause charging when you notice the temperature is exceeding fifty degrees Celsius,


Sulfation happens when a battery has badly discharged. It’s a natural process that crystallizes the electrolytes in a battery after they have been left inactive for too long. The longer the battery sits without being charged or incorrectly charged, the greater the sulfation may increase. Charging alone may eliminate sulfation but sometimes, it might not be enough or the battery might not return to its full capacity afterward. At this point, it is best if you consider getting a new battery 


Batteries are meant to be reliable, and that is why most users research how to test a deep cycle battery to ensure durability. What every battery user should understand is that maintaining a battery starts right from the point of purchase. Buy the battery with the right voltage for the device you want to use it with and ensure you charge right. Also, test regularly to make sure that your battery is in the right shape and if not, consider a replacement.

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