Deep Cycle Battery 12v-Definition, Voltage And Charging Methods

Aug 10, 2020   Pageview:57

Batteries have become one of the most important inventions in the last couple hundred years. The first battery was invented by Alessandro Volta in 1800, which has dramatically improved over the next two centuries. Nowadays, there are a lot of different kinds of batteries. Here is everything you need to know about 12v deep cycle batteries:

What is a deep cycle battery 12V

A deep-cycle battery is, as the name suggests, a battery that is designed to handle a lot of stress. In simpler words, a battery that is designed to work at low voltage. Lead-acid batteries are the most popular types of batteries in the world.

They are used in vehicles, UPS machines, transformers and generally any sort of big machinery. The problem with lead-acid batteries, however, is the fact that they lose precious charge cycles & deteriorate fast if they reach a charge state of lower than 50%.

A deep cycle battery can hold a charge of as low as 20% without losing charge cycles extensively. Here are a few facts about deep cycle batteries:

Lighter & updated

Deep cycle batteries are used in submarines, recreational vehicles, forklifts, golf carts and as a sort of backup for renewable energy in off-grid buildings. The reason why deep cycle batteries are popular for these applications is that they are lighter and can carry more energy per area.

Can last more

As mentioned earlier, a normal lead-acid battery loses most charge cycles when its overall charge drops up to 50% or lower. A deep cycle battery can handle discharges of up to 80% to 85% without losing more cycles. In other words, a deep cycle battery is 30% to 35% more efficient than a normal, average battery.

Easy to maintain

Because they generally hold their charge better than normal batteries, deep cycle batteries are very easy to maintain and require no complex maintenance. This is also why companies that sell deep cycle batteries give extended warranties.

Is pretty durable when discharging

Most lead-acid batteries are designed to discharge a little energy and then begin recharging again. This is especially useful for vehicles. However, when using transformers and UPSs, it is easily visible how difficult and inefficient this mechanism can be. A deep cycle battery can provide almost twice the charge as a normal battery, but also discharge built-up energy more efficiently.

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Different types of deep cycle batteries

There are multiple types of deep cycle batteries:

AGM battery – batteries made out of absorbed glass mat and are the most popular type available. They are sealed and pretty durable, and mostly used in submarines.


Lithium-ion battery – the lithium-ion battery is one of the most durable types of batteries in any scenario as they are used in mobile phones and so on. Deep cycle lithium-ion batteries are usually used in newer solar-powered houses and offer excellent bang for their size.

Gel battery – gel battery is a type of valve-regulated lead-acid battery that provides excellent protection and no maintenance.

Wet cell battery – probably the oldest type of rechargeable deep cycle battery which contains a liquid in an unsealed container. Needs a lot of maintenance but are cheap and easy to troubleshoot.

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What voltage should a deep cycle battery read

6-cell deep cycle batteries usually operate at a normal voltage of 12V under normal conditions. This is usually the smaller answer. Do note that the actual voltage applied, and the voltage that should be read by a deep cycle battery depends on various factors like room temperature, type of battery used, and the method used to charge the battery.

If you are looking for a complete guide on the factors and facts you need to look out for, to maintain a healthy voltage, we have listed all of them below:

Voltage for charging wet-cell batteries

Wet cell batteries, or popularly known as flooded lead-acid batteries are a type of battery that requires little to no maintenance and are the oldest types of deep cycle batteries. Considering the batteries are put in an environment of room temperature, single wet-cell batteries should read a voltage of 2.25 to 2.45 volts depending on how much they have been used.

A fully charged six-cell deep cycle 12 volt flooded battery should read about 11.95 to 12.7 volts at a battery temperature of around 25°C. If you see the voltage dipping, the problem might be with the battery itself and you should probably get it checked.

Voltage for charging AGM & Gel batteries

Both AGM and gel batteries fall under the category of valve-regulated lead-acid batteries. Following the same conditions as flooded batteries, the average one-cell valve-regulated lead-acid battery should read a battery charge current of no more than 2.4, but also no less than 2.25. If you are seeing a spike in the readings, you might need to check whether the battery is overheating. Heating up of batteries is normal, but overheating may be a sign of lethality and things going wrong.

Similar to the fully charged flooded battery, an AGM/gel battery with 6 cells should read about 12 volts of current, give or take a little.

How do you charge a deep cycle battery 12v

Charging a deep cycle battery 12v is pretty simple. Here is a step-by-step guide:

Clean the terminals of the battery with the help of latex gloves, paper towels and fine-grit sandpaper. You will also need safety glasses in case any particle becomes airborne.

Use the sandpaper to thoroughly clean the terminals of the battery and ensure that there is no rust or dirt. You can also use a mixture of baking soda and water to make it easier to clean.

Ensure that you have the correct charger for your deep cycle battery. Using generic chargers can not only decrease the lifetime of the battery but also slow down the charging of the battery.

Turn the battery off while not in use or when charging for the best experience and lifetime.

Never equalize a deep-cycle battery no matter how much people might say so. Equalizing will not put more years into your battery. It will destroy what’s left of your old battery too.

Final Thoughts:

We hope that this simple article on deep cycle battery helped you understand what a deep cycle battery is, how to charge one and what voltages are the safest for the various kinds of deep cycle batteries.

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