Is a battery just a battery? They are designed to store energy and release it when it is needed. But it is important to remember that there are many different types of batteries available.
Each battery you can get these days will suit one specific purpose about how you use them. This is why you must understand just what each different battery is and how they work.
This article discusses how to charge a deep charge battery properly. These batteries may look like the kind you usually see in a car but are, in fact, quite different.
What Is A Deep Cycle Battery?
A deep cycle battery may look like a car battery for those unfamiliar with these batteries. Deep cycle batteries are lead batteries that can provide constant energy for an extended period. They are also designed to run reliably when 80% of the power has been discharged.
The discharge level is a “deep cycle” and is different from either a starting or cranking battery. A Starting battery only provides a vehicle with a short burst of power before it needs recharging. While a deep cycle battery will provide much less power but for a longer time period.
Deep Cycle Battery Charging Instructions: What To Consider To Charge A Deep Cycle Battery Properly?
There are several things you need to consider when it comes to charging a deep cycle battery properly. Below we look at what these are.
In order to do this, there are three questions that you need to answer. These will provide you with sufficient information so you can choose the right charger for your deep cycle battery.
- What sort of charger is needed for a deep cycle battery?
- What amperage should a deep cycle battery be charged?
- When should a deep cycle battery be charged?
1. What kind of charger do you need for a deep cycle battery?
Choosing the right battery charger is the first and key factor that will help you to correctly charge your deep cycle battery and extend its lifespan.
But how do you choose a battery charger that meets your particular requirements? You need to answer the 4 questions below in order to choose the best one for your needs.
Question #1: Do I need a special charger for a deep cycle battery?
Choosing the correct battery charger will improve your battery’s life. But choosing the wrong charger can damage your battery.
They design regular chargers for flooded cell batteries and they will charge them quickly at a high ampere rate. The high amps can damage AGM and GEL batteries.
Instead, make sure you have a modern smart charger that works with AGM and GEL batteries specifically.
The fundamental difference between a regular and deep cycle battery charger is the charging speed. Flooded batteries can be charged at a much higher rate than AGM or GEL. This means they will become fully charged in a shorter time.
Chargers specifically designed for AGM have two distinct differences over regular chargers:
- The charger regulates the charging rate, ensuring that your battery can reach 100% without overcharging.
- Most AGM chargers will go through three distinct stages:
- Bulk Charge Stage: This is the main charging cycle. It will use a low amperes charge to avoid overheating the battery.
- Absorption Charge Stage: Once the battery is 80% charged, it enters this stage. The current supplied by the charger gradually reduces until the battery is at 100% charge.
- Float Charge Stage: This stage maintains the battery at 100% by monitoring and using a trickle charge to top up as necessary.
Question #2: What is the capacity of your deep cycle battery?
Ideally, the charger should be able to put out a minimum of 10% or a maximum of 20% of the actual battery Ah capacity.
Question #3: What voltage battery charger do I need?
You need to select a charger with the correct voltage as your deep cycle battery. So if your battery is 12-volt, you will need a charger that goes up to 12-volt. For a 24-volt or 36-volt battery, you will need a charger that has the same voltage as these.
Question #4: So which are the best battery chargers for deep cycle batteries?
You can buy many chargers to help recharge a deep cycle battery. Below are two of the best for you to use for charging deep cycle batteries:
Top 1: Minn Kota charger for your deep cycle battery?
Minn Kota Digital On-Board Charger
The Minn Kota charger has been digitally designed to deliver the right amount of power each time you plug it in. This will help to ensure that your battery is neither over nor undercharged, which helps to lengthen the battery’s life.
The inclusion of an LED status display means that you can quickly see how far along the charging process is. It will also indicate if the charger has been connected to the battery correctly.
With its automatic multi-stage charging features, it means you only need this one to charge batteries ranging from 12 to 48 volts. Plus, it can be used for AGM. Gel and flooded lead-acid batteries.
Temperature can affect how quickly it takes for a battery to charge. But with this charger, it can sense what the temperature is and then adjust itself to ensure that it continues to produce a fast, accurate charge.
Also great: Noco Genius5 charger
Noco Genius5 Smart Charger
If you are looking for an affordable and reliable charger for your deep cycle battery, go for the Noco Genius5 charger. This is a safe battery charger that you can use on a daily basis.
It has also been designed to be used occasionally, especially useful for people who don’t need the heavy capabilities of a charger to use along with heavy-duty or high amperage items.
This battery charger is suitable for use with both AGM, wet cell, gelled electrolyte, and many lithium batteries.
You can use this to charge a mains battery on its own along with any other batteries afterward. You will find that this battery offers you fast, reliable charging that is also efficient.
The added benefit is that you can restore your deep cycle batteries using 12V Repair Mode.
2. What amp should I charge my deep cycle battery?
As a quick rule of thumb, you need a charger capable of being able to put out a minimum of 10% and a maximum of 20% of your battery’s Ah capacity.
However, the recommended Ah capacities for some chargers are as follows:
- 5A Charges – 50Ah Battery
- 7A Charges – 70Ah Battery
- 10.0A Charges – 100Ah Battery
- 15.0A Charges – 150 Ah Battery
3. When to charge a deep cycle battery?
If you would like your deep cycle batteries to last for several years without little or no damage, you should charge them before they have gone below 50% discharge levels.
The deeper the discharge, the more likely the total cycle life of such batteries is reduced. Charging such batteries to 50% of their capacity rather than 100% will produce an additional 40% extra amperes throughout the battery’s life.
Charging A Deep Cycle Battery: 2 Amp or 10 Amp?
It is better to slowly charge a deep cycle battery as these aren’t designed to be charged quickly. This is because the batteries do not have the facilities to cope with the extra heat produced through rapid charging.
When should you slow charge the battery?
You should use a low amperage charger, for example, a 2 Amp charger when the battery hasn’t been completely drained of power and still has some charge in it.
When should you fast charge the battery?
A high current charger (10A charger for example) is only recommended for charging a deep cycle battery that is totally dead and has no power left.
If you try to charge such batteries quickly, they may not reach their total charge capacity. So you will find yourself having to recharge this battery more often, which will shorten its battery life.
How To Charge A Deep Cycle Battery Properly?
Once you have the correct charger for charging these batteries, you’ll find the whole process easy. Simply follow the steps below:
- Find a well-ventilated area to charge your battery.
- Ensure the battery terminals are clean. Remove any grease and dirt. You can use wire wool if required.
- Connect the red (positive) cable to the red terminal first. Then connect the black (negative) terminal.
- Make sure cables are tightly connected to the battery terminals.
- Plugin your charger and switch it on.
- If the charger has an indicator, make sure it is charging.
- A smart charger will tell you when it has finished. If you are using a non-smart charger, remember to disconnect it after the charge time you calculated.
- To disconnect: Unplug the charger, and remove the black cable first, followed by the red cable.
- Grease the terminals to prevent corrosion.
How Long Should You Charge A Deep Cycle Battery?
It is vital to note that how long it takes to charge such batteries can vary and depend on many factors:
- How much charge is left?
- What is the battery reserve capacity?
- What is the battery’s amp-hour capacity?
- How old is the battery?
- How well has the battery been maintained?
So, of course, if you’ve used 80% of the battery’s power, then, of course, it will take longer to recharge than a battery where only 50% of its power has been discharged.
It is best if you use the formula below to help with determining the time of charge needed using the following steps:
Hours of charge = ((AH x % of charge needed) : Amp setting of the charger) x 1.25 +1
(*) You have to +1 hour because charging a deep cycle battery requires more than 1 hour compared to a regular battery.
How long to charge a deep cycle battery at 2 amps?
The formula will look like this:
- (100 x 0.5)/2 x 1.25 = 31.25 hours of charge.
- Then add a further 1 hour for charging a deep cycle battery: 31.25 + 1 = 32.25 hours
The total hours of charge needed for a deep cycle battery using a 2A charger are 32.25 hours.
How long to charge a deep cycle battery at 6 amps?
- (100 x 0.5)/6 x 1.25 = 10.4 hours of charge.
- Then add a further 1 hour for charging a deep cycle battery: 10.4 + 1 = 11.4 hours
The total hours of charge needed for a deep cycle battery using a 6A charger are 11.4 hours.
How long to charge a deep cycle battery at 10 amps?
- (100 x .50)/10 = 5 x 1.26 = 6.26 hours of charge.
- Then add a further 1 hour for charging a deep cycle battery.
The total hours of charge needed for a deep cycle battery are 7.25 hours.
In conclusion, to completely charge a 50% discharged 100Ah deep cycle battery, it will take 32.25 hours if the charging current is 2 amps. At a 6 amp current, the time it takes to fully charge a 50% discharged 100Ah deep cycle battery is 11.4 hours. And with a 10 amp charger, it takes 7.25 hours.
What Is The Best Way To Charge Deep Cycle Battery?
Invest a smart charger
It is a good idea to invest in a smart charger as these will know when the battery needs recharging and just how much charge it needs. Plus, you can leave them connected to the battery for as long as you like.
Minn Kota Digital Charger
Noco Genius5 Smart Charger
Never let your battery discharge below 50%
It is best never to let the total battery discharge go below 50% (12.0VDC). If you find that you are regularly discharging the battery to 25% or lower, you will either need to invest in larger batteries or be prepared to replace them every two years.
Don’t forget to maintain your battery when not in use over the winter
If you don’t intend to use your battery through the winter months, you can do several things to keep it in good condition.
- Connect it to a float charger and then leave it to do its work
- You can fully charge the battery, and then every month, just put it back on the charger to top it up
Deep Cycle Battery Won’t Charge: Problems And Troubleshooting
- Try the charger with another battery, if possible. As with any electrical system, it can fail.
- Check that you have the correct charger for your battery. If you have an AGM battery, it’s advisable to use an AGM charger. It has different functions specific to the type of battery.
- Sulfated battery. Over time, batteries can become sulfated if they never achieve a fully charged state. Eventually, it will prevent the battery from charging 100%, and it will hold less charge.
- If your battery is old, it may just need replacing. Good battery life is anything over around four to five years. Beyond that age, they will start to fail.
FAQs
How to charge an AGM battery?
When charging an AGM battery, it is essential to use a charger designed specifically for this purpose. Also, remember you should never charge such batteries over 14.8 volts.
Can you charge a deep cycle battery while in use?
Yes, it is possible to charge a deep cycle battery while in use, but you will need to be able to regulate the voltage so that the charger voltage doesn’t pass over to the load side.
Do I need a special charger for a deep cycle battery?
Yes, you need a charger specifically made for use with deep cycle batteries. Never use a regular battery charger on such batteries as they cannot handle the excess heat or rapid charging of such.
How To Charge A Deep Discharge Battery?
Once you have the correct charger for charging these batteries, you’ll find the whole process easy. Simply follow the steps that the manufacturers of the charger you are using provide.
Charging a deep cycle battery 2 amp or 10 amp?
Deep cycle batteries are designed to be charged at low amp ratings. Charging at higher rates can cause damage and will prevent the battery from reaching a fully charged state.
Can you overcharge a deep cycle battery?
Yes, this is possible with any battery if you are using an older-style simple charger. Use a smart charger to avoid overcharging.
Is it OK to trickle charge a deep cycle battery?
Trickle charging is the correct way to charge a deep-cycle battery.
How to tell if a deep cycle battery is bad?
If you suspect there is a problem with your battery, you can test it using a multimeter. The table below gives some possible indications and associated issues:
| Voltage reading | Charger indication | Problem |
| 0V | N/A | Dead battery, possibly a short circuit |
| 10.5V or less | Charging | Most likely a dead battery cell |
| 12.4 or less | Fully charged | Sulfation |
Measuring the voltage is a useful way of assessing the condition of the battery. The following table gives typical values that you should see.
Let’s Wrap Things Up
There are many ways for you to recharge deep cycle batteries. But the best course of action would be to use a smart charger that will help control how much and for how long the battery needs charging.
We hope you find this article of interest and would love to know what you think. Why not drop us a quick comment below.
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