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How Long Does it Take to Charge a Deep Cycle Battery? – Everything You Need to Know About Safely Charging Your Solar Batteries

How Long Does it Take to Charge a Deep Cycle Battery

How Long Does it Take to Charge a Deep Cycle Battery? –  Everything You Need to Know About Safely Charging Your Solar Batteries


Whether you are planning to run an off-grid system, or you are looking to add a battery bank to your grid-tied solar power system, you will need to familiarize yourself with deep cycle solar batteries.

Deep cycle batteries are uniquely suited for solar applications, as they are designed to be charged and discharged over and over again. Where other types of high-capacity batteries, like automotive batteries, are only capable of discharging a small amount of the power they store, deep cycle batteries can be discharged down to extremely low power levels without needing to be jump started. This means the stored solar electricity stored within your deep cycle batteries can actually be used at your convenience.

How Can We Help? 

To help you learn everything you need to know about using and charging a deep cycle battery, we have provided this useful guide. We will explain how long it takes to charge a deep cycle battery, how you can prep the battery for installation, and how you can extend the lifespan of your solar batteries

From there, we will also recommend some high-quality deep cycle batteries and other pieces of solar equipment you can use to build an efficient solar power storage system.

Not only is it important to learn how to properly charge your deep cycle batteries from a safety perspective, it will extend the lifespan of the batteries and ensure they are charging and discharging efficiently at all times!

What is a Deep Cycle Battery? 

As mentioned above, a deep cycle battery is a type of power storage device that is designed to provide sustained and reliable power. Unlike most types of batteries, which are usually designed to provide short bursts of power before they need to be recharged, a deep cycle battery can be discharged down to extremely low levels.

While they may look similar, automotive batteries are only designed to supply a short burst of electricity, which is used to start the vehicle’s engine. Once the power level of an automotive battery is drained too low, it will need to be boosted. On the other hand, you can access more of the power stored inside a deep cycle battery, which is why they are ideal for solar applications.

Basically, you can simply charge the battery each day with your solar panels and then draw as much of that power as you need to charge your electronic devices and power your electric appliances. Not having to worry worry about the consequences of discharging the battery too low means you can use your stored solar power exactly how you would prefer.

So, How Long Does it Take to Charge a Deep Cycle Battery? 

While it may sound like a fairly straightforward question, understanding how long it will take to charge a deep cycle battery actually involves a fairly complex answer. To understand how long it takes to charge a deep cycle battery, we will need to take a look at the charging stages: 

Stages of Charging: 

  • The Bulk Stage – this is the first stage in the charging process, wherein the maximum voltage is detected and transferred to the battery. During this stage, the charge controller will keep the voltage at a consistent level. After this stage is complete, the voltage will decrease.
  • The Absorption Stage – this lower voltage stage of charging also increases the battery’s internal resistance. Once the battery is getting close to fully charged and its total storage capacity is almost reached, the internal resistance of the battery will be just about at its highest level.
  • The Float Stage – the absorption stage is complete and the battery is just about fully charged. At this point, the trickle, or maintenance charge, will kick in. During this stage, the charge controller will allow just enough electricity to flow to the battery to maintain its full charge, as any battery will slowly and naturally lose some of its charge. The float stage prevents the battery from losing too much of its stored energy through natural discharge. This is particularly important if your deep cycle battery is being used as an emergency source of backup power, as it will ensure that your battery will have a full charge when you need it.

Each battery will move through these three stages at different speeds and the total charge time will depend on both the size of the battery and the amount of power that is flowing to it. 

Deep Cycle Battery Charge Time Calculations:

There is no simple answer for how long a deep cycle battery will take to charge. This is because the total time will depend on the capacity of the battery being charged, as well as the power rating of the power sources being used to charge that battery. 

Basically, you need to make a quick calculation using two pieces of information: the amp rating of the charger being used and the capacity of the deep cycle battery.

To find the charge time for your deep cycle battery, simply divide your battery’s capacity by the amp rating of the charger. If, for example, you had a deep cycle battery with a capacity rating of 200 amp hours and you had a charger that had a power output of 10 amps per hour, it would take 20 hours to refill the battery. 

Obviously, this is an oversimplified example. Chances are, your solar array and charge controller will be able to charge your deep cycle battery in less time than 20 hours, but the example helps illustrate the point that your actual charge time will depend on the capacity limit of your particular battery, as well as the specs of the other pieces of solar equipment in your system. 

Charge times will also vary depending on how efficiently your solar equipment can operate. For example, the amount of direct sunlight your solar panels are exposed to will determine how efficiently they are able to operate.

Your deep cycle battery will also lose some of its storage capacity over time, as batteries of all types degrade with use. If you find that your battery is no longer holding the same charge it once could, you can perform a few quick tests using a multimeter to make sure it is actually the battery that is causing the problem, rather than some other piece of equipment within your solar power system. 

How to Prep a Deep Cycle Battery for Installation

If you want to get the most out of your solar power system’s battery bank, you will want to take the time to install your deep cycle batteries properly. The first step in prepping a deep cycle battery for installation is to visually inspect the battery. 

Make sure the battery’s housing does not have any cracks, splits, visual signs of corrosion, or any other obvious issues. You should also make sure that you are choosing an appropriate and efficient charge controller to pair with your battery. The charge controller will regulate the voltage and current from your solar panels to ensure the battery charges safely and efficiently. A charge controller will also prevent overcharging issues, which can permanently damage a deep cycle battery. 

You will also need to select an appropriate power inverter for your battery. Since solar panels convert sunlight into DC power, you will need a power inverter that can convert that electricity into AC power, as this is the type of current that your electronic devices and appliances require. Power inverters can also help with efficiency by tracking the voltage of the solar array to identify the maximum power that the modules can operate. This feature also helps reduce the amount of time it will take to charge your deep cycle battery.

For more information about choosing the correct solar power inverter for your specific deep cycle batteries, we encourage you to take a look at our Collection of Solar Power Inverters.

Once installed, you will also want to keep your deep cycle batteries protected from the elements. If you can, position them in a location where the temperature will remain stable, as this will protect the battery, reduce charge times, and improve efficiency.

Choosing the Right Deep Cycle Batteries and Solar Equipment

If you are in the market for a new deep cycle battery, you will be able to find a high-quality option by shopping our Deep Cycle Solar Battery Collection. We carry a wide range of deep cycle solar batteries from some of the best brands in the industry.

This BattleBorn 100Ah 12V LiFeP04 Deep Cycle Battery works exceptionally well as part of a solar power storage system. It features a built-in battery management system and it can be fully discharged. Given that it comes backed with an outstanding warranty and it is available at an affordable price, it is the perfect option for beginners, as well as those that are more experienced with solar power.

Our Solar Panel Connectors Guide can explain how you can wire everything together using MC4 connectors and solar extension cables.

Final Words

While the amount of time it will take to charge your deep cycle batteries will depend on a few factors, you can ensure your battery bank is charging and discharging efficiently by checking the state of charge with a voltmeter or a multimeter. 

By keeping your batteries in a dry place with a stable temperature, you can extend their overall lifespan. Investing in a high-quality charge controller will also ensure your batteries do not suffer from overcharging issues. 

If you ever have questions about charging deep cycle solar batteries, or any other questions relating to your solar power system, we are here to help!



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