How Do I Know If My Battery Is AGM?

If you’re looking into buying a new battery for RV, you may have seen the term “AGM” thrown around and wondered what it meant. For maintenance, repair, or replacement purposes, you need to know the type of car battery you have. AGM is more prevalent these days, but the traditional lead-acid type has not vanished just yet. How do I know if my battery is AGM?

An AGM is a type of lead-acid battery that offers higher performance and longer lifespans than the traditional flooded type. But to get the benefits of an AGM battery, you have to make sure it’s an AGM – and not just a flooded battery in disguise. Let’s discuss some unique benefits of this battery and how to tell if battery is AGM.

What Is an AGM Battery and What Are Its Benefits?

AGM stands for “absorbed glass mat,” and it’s a technology used in lead-acid batteries to immobilize the battery electrolyte (the sulfuric acid solution that makes up most of the battery contents).

The immobilized electrolyte (sulfuric acid) is absorbed into a fiberglass mat separator, making the battery more spill-proof than conventional batteries. It means that it will still function properly when the battery is turned on its side or upside down.

AGM batteries have superior cranking power and deep cycle capabilities compared to standard batteries. They can be discharged as low as 0% and recharged back up to 100% without any problems.

But these batteries are also more susceptible to damage from overcharging than standard batteries. They have a lower tolerance for voltage spikes. You have to follow the correct charging parameters to protect them from damage.

AGM batteries are popular among people who use their cars/RVs for short trips or off-roading because they charge faster than other types of batteries due to their higher surface area. AGM batteries also tend to last longer because they don’t leak acid when they get hot as flooded cells do.

Now, let’s move into how to tell if my battery is AGM.

How Do I Know If My Battery Is AGM?

Is my battery AGM? If you’re wondering how to check if your battery is AGM and not flooded, you’ve come to the right place. We’ll get you through the steps so you can find out whether your battery is the right one for your RV.

How do I know if my battery is AGM? Follow these procedures:

Check for labels

The good news is that you can usually figure out which kind of battery it is by looking at the battery itself or checking the battery’s label.

If the label is still in good condition, see if it has “AGM” or “Absorbed Glass Mat” written on it. The label could also say “sealed” or “maintenance-free” to indicate that it’s an AGM.

However, if the battery label displays “flooded” “Wet” or has removable caps, it’s probably a flooded lead-acid (FLA) battery.

Examine the upper top side of the battery

When the label is illegible, you have to examine the battery physically. Check its upper-top design as AGM batteries have a pretty distinct construction than the regular lead-acid units.

If the top is flat with positive and negative terminals protruding out, your battery is likely an AGM. Since these batteries are properly sealed, you won’t find any opening to unlatch the top cover. On the other hand, the batteries that use liquid electrolytes will have a removable lid.

Give the battery a good shake

Lift your car battery and give it a little shake. Can you hear the liquid sloshing around in there? If not, you have an AGM battery. But the sound of liquid splashing indicates that it’s probably a lead-acid battery (because lead-acid batteries have a liquid electrolyte).

Check the voltage

Another way to find the battery type is by checking its voltage. You can use a multimeter to check the AGM battery minimum voltage.

A full-functioning AGM battery will draw between 14.6 and 14.8 volts. This range is between 13.8 and 14.4 for standard lead-acid batteries. So, there’s a clear difference in the voltage requirements of these battery units.

Keep a tab on the maintenance schedule

Do you have to refill my battery with water often? If so, your battery probably isn’t AGM because these kinds of batteries don’t require water refills as much as other types do. Though they still need some maintenance and cleaning now and then.


How do I know if my battery is AGM? Well, you can indeed find out by following the procedures mentioned above. If you still can’t figure it out, take the car to a servicing shop and ask the mechanic there.

Scott Wilson
Scott Wilson
Scott Wilson is a seasoned RV traveler and professional mountain biker with a great sense of humor. After earning a Master's degree in Automotive Engineering from Columbia University, Scott spent years working as an RV technician at Camping World and Outdoorsy. Today, he enjoys exploring the US in his fifth wheel and truck with his wife. With over 15 years of RV living and road tripping experience, Scott now shares his knowledge and expertise as a travel blogger, helping others make the most of their RV adventures.

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