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Can I Use an AGM Battery in My RV?
Yes, you absolutely can use an AGM battery in your RV or camper!
While you can use AGM batteries as starting batteries, you’re probably considering AGM batteries for your “house” batteries.
As you’ll read in the next section, there are many advantages to using an AGM battery for your RV. The biggest two advantages are the lack of maintenance and the low self-discharge!
There are a few disadvantages, too. AGM batteries can be considerably more expensive (although far less expensive than a lithium battery). AGM batteries should only be discharged to 50-60 percent, while premium flooded batteries can be discharged down to 70-80 percent.*
However, AGM batteries are rapidly becoming the standard for RV house batteries. You should consider using one!
What Are the Advantages of an AGM Battery in an RV?
There are many advantages to using AGM batteries for your deep-cycle RV house or starting batteries!*
- Spillproof. The water-electrolyte in an AGM battery is absorbed in a glass mat separators. If you tip over an AGM battery, the water won’t spill out! (Don’t try that with a regular battery, kids).
- Maintenance-free. Because the battery is sealed, moisture vapor can’t evaporate! You don’t need to check the electrolyte levels, measure the cells with a hydrometer, etc. In fact, opening an AGM battery will normally void the warranty – so don’t do it!
- Vibration-resistant. Their stout, solid construction makes AGM batteries perfect for the bumps, jolts, shocks, and thuds of the #RVlife.
- Any orientation. Unlike flooded batteries, which must be mounted in the upright position, AGM batteries can be mounted in any position except upside down.
- Lower self-discharge. All batteries self-discharge (aka, lose energy) when stored. Not good. As you know from my ultimate battery guide, allowing a battery to deep discharge is a good way to kill it! That’s why all lead-acid batteries should be trickle-charged while in storage. Anyway, AGM batteries self-discharge at 2-3 percent a month. That means you can store them on a shelf for up to 6-12 months without risking damage from sulfation!
- Extreme temperature resistance. AGM batteries fare better in cold weather and are less likely to freeze than flooded batteries. Great for winter boondocking!
Is a Sealed Lead Acid (SLA) Battery the Same as an AGM Battery?
Well … an AGM battery is an SLA battery, but an SLA isn’t always an AGM battery! One is a subset of the other.
To make matters more confusing … SLA is also referred to as Valve Regulated Lead Acid (VRLA)!
To fully explain the terminology, we must wade into the deep-ish end of the pool. A conventional “wet” or “flooded” lead-acid battery vents hydrogen gas when it is being charged due to the production of excess oxygen at the anodic plate. Since water (H2O) is made of hydrogen and oxygen (H2O), over time, the battery loses water. It literally dries up, like a squeezed sponge.
Sealed lead-acid batteries elegantly solve this problem using recombinant technology. All the oxygen is reconstituted with hydrogen and kept inside the battery. No more venting required! No more maintenance! Hurray! A one-way pressure-relief valve traps everything inside – except in an emergency, when the vent will open to relieve bomb-like pressure.
As I said, an AGM battery is a type of SLA battery. But there are also other types, like gel batteries. What makes an AGM battery unique is the suspension of the electrolyte: The electrolyte in AGM batteries is completely absorbed in separators consisting of matted glass fibers.
Alright, we’re up to our waists in chemistry. Let’s return to shore! No, an SLA battery isn’t always an AGM battery. But since AGM batteries are so popular (and gel batteries aren’t), most of the time, one equals the other.
Will My RV Charge an AGM Battery?
Almost all modern RV 3-stage converters can properly charge AGM batteries. You can reference your Owner’s Manual from WFCO, Progressive Industries, or another manufacturer for more details.
However, antiquated single-stage converters cannot properly charge AGM batteries! In particular, you might cause thermal runway, which can A) cause catastrophic damage to your battery and/or B) make it explode. So if you’re still rockin’ a converter from the ‘70s or ‘80s, please upgrade!
In some cases, AGM batteries are not recommended for use as engine starter batteries. There may be concern about the alternator/charging system being able to properly charge an AGM battery to the higher float voltage required for a full charge.
In most cases, AGM batteries can be used as starter batteries without a problem, but check with your coach/automobile manufacturer. For the most part, AGM batteries can be charged (albeit imperfectly) with the same charging profile as flooded batteries.
Note: If you’re trying to charge your RV trailer battery with your tow vehicle, then be warned that AGM batteries will tend to max out around 80% charge; most umbilical cord connections simply lose too much voltage to achieve float voltage.
What Size AGM Battery for An RV?
You can use the same size AGM battery as your regular flooded battery. So if you have a 100AH battery, just buy another 100AH AGM battery. Easy peasy.
Can I Mix AGM Batteries With Other Types?
Never, ever mix battery chemistries in a battery bank, such as lead-acid and lithium. That is extremely dangerous and ineffective.
However, you might be considering mixing AGM batteries with conventional flooded lead-acid batteries – but this is also not recommended: AGM and flooded lead-acid batteries have a slightly different charging profile. Plus, two different batteries will typically have different plate construction and discharge profiles; one may be dual-purpose marine/RV, and one may be a dedicated deep-cycle battery.
TL;DR: Don’t mix batteries by age, chemistry, type, or size!
What Is The Best AGM Battery for an RV?
If you are purchasing a deep-cycle battery for RV house batteries, then here are a few battery brands you should consider:
- Renogy: IMHO, Renogy offers the best blend of performance and price point. Renogy batteries are good for RVs, solar battery banks, boats, and other uses.
- Optima: Optima is known for spiral cell construction, which is best for ultra deep-cycle charges.
- Interstate: Well-known manufacturer of reliable lead plate marine/RV and deep-cycle AGM batteries. Available from many RV dealers.
- Universal Power: Best for the budget buyer! Available online – just make sure to buy from a reputable seller. Doesn’t do extreme deep discharges as well as Optima, Renogy or Interstate.