How to Load Test AGM Deep Cycle Battery: Step-By-Step Process

AGM batteries are lighter than their flooded lead-acid counterparts, require no regular maintenance, and provide consistent power with high reliability. This is why AGM batteries got more popular than other batteries.

But how to load test AGM deep cycle battery? Put the positive battery terminal into the red clip of the load tester and the negative terminal into the black clip. The load test should be allowed to continue for 10–15 seconds before being terminated. But there’s a step-by-step process for running the test properly.

Carrying out the load test of AGM batteries is easy with the right set of tools. But there’s a catch. So to help you with that, we’re with this detailed step-by-step guide that will come in handy to carry out this task.

What is AGM Battery?

What is AGM Battery

To distribute the electrolyte solution evenly between the plates, an AGM (battery uses a unique glass mat separator. The construction of this material makes it possible to hold the electrolyte in a “dry” or suspended condition rather than free liquid form by saturating fiberglass with it.

The use of AGM batteries, or those made from an absorbed glass mat, gained popularity in the 1980s. Once only found in motorbikes, the military, aviation, and submarines, they are now commonplace in regular cars and trucks.

In contrast to flooded lead-acid batteries, AGM batteries do not require regular maintenance. Their purpose is to supply high beginning amps for a short time and power devices for a longer time.

By contrast to the free-flowing liquid electrolyte of flooded batteries, the separators of AGM batteries absorb and suspend the electrolyte. The fiberglass used in AGM batteries is a key component in their ability to keep the electrolyte in a solid rather than liquid state. The term “absorbent glass” describes this material perfectly.

Precautions For Safety Measurement

How to Load Test AGM Deep Cycle Battery

Here are some safety measures that you can take for the better performance of AGM batteries.

  1. Always recharge AGM batteries before long-term storage. Ventilate and cold and dry store your battery. Discharged batteries can sulfate.
  2. Take a small amount of power from the deep cycle battery and use it to maintain a steady voltage for a while. That means avoiding using powerful equipment because it drainage the battery.
  3. Using the recommended charging voltage for your AGM battery is essential for maintaining its optimal performance. Never connect your AGM battery to a standard gasoline generator.
  4. Determine the voltage with your multimeter. Insert the multimeter’s metal tips into the battery terminals.

How to Load test AGM Deep Cycle Battery

How to Load Test AGM Deep Cycle Battery

Here’s the detailed process of doing the load test on the AGM battery. Let’s check out.

Cycle Battery

  1. Turn the Multimeter On

The first thing is to turn on the multimeter for the connection. You can turn the dial on the meter or click the button corresponding to the measurement function to set it to measure voltage.

  1. Place the Sensor

Now coming to the second step is to place the sensor in the proper place. The meter’s red wire and its sensor should be connected to the “+” connector of the AGM battery. Position the sensor so that it is at the end of the black wire and then connect that to the “-” connector of the AGM battery.

  1. Read Multimeter 

Now, this step will help you to understand the accurate voltage of the multimeter. A completely charged typical AGM battery will produce around 13 volts of voltage, which is somewhat higher than the 12 volts that will be printed on the battery’s case. 

If the voltage is below 10 volts, the battery needs to be recharged. Check the voltage immediately after charging and again after waiting a few hours. A new battery is probably required if the voltage reading declines by more than a volt or two when tested again.


How to Load Test AGM Deep Cycle Battery
  1. Read the Label

Each fuse has an amp rating, which indicates the maximum allowable current flow. This maximum continuous current can pass through the fuse under the given operating conditions. However, AGM’s amp ratings are by reading the label that is located on the side of the battery.

If the battery is intended to be used in a vehicle, the label will have the initials CCA, which stands for cold cranking amps, followed by a number that corresponds to the amperes. 

On the label, for instance, you might find the notation CCA 70 printed. Alternately, if the battery is used in a golf cart, it can contain letters. Ah, which stands for ampere-hours, followed by a number.

  1. Divide the CCA

AGM batteries for vehicles will have a label with their CCA rating. The battery’s Cold Cranking Amps (CCA) measure its ability to produce electricity at freezing temperatures for 30 seconds.

An operating voltage of 7V is used to accomplish this. The typical CCA ranges from 300 to 700. A higher CCA number is indicative of a more powerful engine.

The battery’s CCA rating must be cut in half. Checking the battery’s condition is finally complete. Assuming the load test reading for your battery is half the CCA. If so, the battery is in good condition.

However, a significant discrepancy between the tester’s reading and CCA indicates poor battery condition and should be investigated further.

  1. Switch On the Load 

Start up your load-gauging device. The alligator clips should be attached to the terminals of the battery; the clip at the end of the red wire should be attached to the “+” terminal, and the clip at the end of the black wire should be attached to the “-” terminal.


Load Test AGM Deep Cycle Battery
  1. Let the Load Test Run

Now running the load tester will let you know whether you’ve done all the steps properly or not. For the test, press the start button, and you have to run the test for 10 to 15 seconds. After 15 seconds, the majority of load testers will automatically shut off.

  1. Read Load Test Meter

The final step of the load test of the AGM cycle battery is to read the load test meter. However, the reading process is as same as the earlier ampere ratings. So charge the battery if the percentage is below 10.

But leaving the battery in the same position for a few hours and if it still doesn’t cross 10, then you might replace the battery. 


  • How much voltage should an AGM battery have?

Standard lead acid batteries require 13.8v – 14.4v to complete a full charge from a state of discharge. However, GM batteries are designed to require 14.6v – 14.8v. Hence most onboard chargers aren’t built to give this range.

  • Can an AGM battery be overcharged?

AGM batteries, like all gelled and sealed devices, are easily damaged by being overcharged. Although these batteries can safely be charged to 2.40V/cell, the float charge should be set to between 2.25 and 2.30V/cell.

  • Is there a reason my AGM battery is losing power so rapidly?

Reduced battery capacity in an AGM battery can be caused by a number of factors, the most common of which is a lack of regular maintenance and charging. Most battery manufacturers stipulate that their products be charged back to full capacity after each use.

  • How long does an AGM battery typically last?

Twelve-volt Gel or AGM batteries have a six-year lifespan if kept fully charged while not in use. The battery keeps 80% of its original capacity even after five or six years of float voltage at a constant ambient temperature of 25 C.

  • Is an AGM battery possible to jump-start?

Avoid trying to jump-start a battery if you notice ice forming inside the cells or if the electrolyte level has decreased to the point where the plates are exposed. Do not try to open the cells of an AGM battery or one that says “Maintenance Free” on the package.


Till now, you got to know how to load test AGM deep cycle battery. However, A deep discharge test is necessary to determine the true capacity of a deep-cycle battery.

Moreover, discharge testing equipment is available at most good battery stores and is necessary for this inspection. But if you’re not comfortable enough to do the test independently, you better do it with an expert.

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Marcelo Araujo-Xavier

Hi, Marcelo Araujo-Xavier is here! I am the author of Batteryhint. I have been working in the battery industry for over 20 years and have a passion for helping people find the best battery for their needs. I have personally tested and reviewed hundreds of different batteries. I'm certified by the International Association of Automotive Battery Manufacturers. I have always been interested in batteries and how they work, so I decided to start this website to share my knowledge with others. I hope you find the information on this website helpful and informative. I will be regularly updating this website with new resources, If you have any questions or comments, please feel free to contact me. I would love to hear from you and help you find the best battery for your needs.

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