For those looking to replace their car’s battery, you will come across multiple acronyms and terminology.
However, for this piece, we’ll be focusing on Absorbent Glass Mat (AGM) and Gel batteries.
Both are types of sealed batteries, or Valve-Regulated Lead Acid (VRLA) batteries, which means they don’t need to be topped up with water as they are maintenance-free.
Also, both batteries can be mounted in any orientation, on their side, upright, or upside down. This is because the liquid inside the battery is locked into place and can’t be spilled.
Now that we’ve brushed over all their similarities, let’s focus on the type of battery.
AGM Batteries: High-Performance Starter
AGM batteries work by soaking up their electrolytes into spongy fiberglass mats between the battery plates. As a basic example of a concept, it’s like a paper towel holding liquid, which allows the battery to keep the electrolytes in place and creates a spill-proof unit.
Why AGM Batteries are Great for Cars
There are numerous benefits to installing an AGM battery in your vehicle. These benefits include:
Quick Power Delivery
An AGM car battery can deliver hundreds of amps in one big burst, far more than the steady trickle needed to power lights or electronics.
That’s why they’re perfect for starting engines, especially in cold conditions when engines need more cranking power.
Most AGM starter batteries are rated for Cold Cranking Amps (CCA), which measures the amount of current they can deliver for 30 seconds at –18°C without dropping below 7.2 volts.
- Small motorbikes/ATVs: ~100–250 CCA (roughly 100–250 amps).
- Cars (compact to midsize): ~400–600 CCA (400–600 amps).
- Large cars / SUVs / diesel engines: 700–900+ CCA (sometimes over 1,000 amps for heavy-duty vehicles).
Holding on to Their Charge
Unlike some older batteries that slowly drain even when not in use, AGMs have a very low self-discharge rate.
That means if you park your vehicle for a few weeks or even months, the battery will usually still have enough juice to start it up again without needing a recharge.
Rough and Ready
Because the electrolyte is absorbed into fiberglass mats, there’s no liquid sloshing around. That makes AGM batteries far more resistant to bumps, shakes, and vibrations.
A significant advantage for off-road vehicles, boats, and motorcycles. They also perform well in cold weather, which is when weaker batteries often struggle.
Fast to Recharge
AGMs can handle higher charging currents, so they get back to full power quicker than traditional flooded batteries.
Combine that with the fact that they’re widely stocked and usually cheaper than gel batteries, and you’ve got a practical, everyday option.
What Else to Keep in Mind?
While there are loads of benefits of fitting your car with an AGM battery, there are a few elements to be aware of.
Even though the AGM is an advanced battery, if misused, its lifespan will be shortened dramatically, such as running them flat (deep discharges). They’re not meant to be drained like deep-cycle batteries.
AGM batteries are also not great at handling extensive exposure to high heat, as it can dry them out internally, which in turn will shorten their lifespan.
For those who live in areas exposed to long periods of high heat, it is best to keep your car out of direct sunlight.
Additionally, compared to old-school flooded lead-acid batteries, AGMs do cost more upfront.
Gel Batteries: The Endurance Type
Instead of soaking the electrolyte into mats like AGMs, Gel batteries mix the electrolyte with silica, turning it into a thick gel.
The gel locks everything in place, which means there’s no liquid sloshing, no leaks, and no need to worry about topping up with water.
Why You’d Choose a Gel Battery
As you can imagine, there are numerous reasons to fit a gel battery into your vehicle, which include:
Deep-Cycle Stamina
Gel batteries are built for steady, long-lasting power. They can be discharged and recharged many more times than AGM batteries, making them ideal for applications where electronics, lights, or equipment are used for hours on end.
Examples of perfect use are in vehicles such as RVs and boats, as well as for solar systems.
Great in the Heat
One of Gel’s standout features is its heat tolerance.
They don’t dry out as quickly in hot climates, so if you live somewhere warm or plan on extended continuous use, a Gel battery often outlasts an AGM.
Low Self-Discharge
Leave one sitting for months, and it will still have most of its charge when you come back.
This characteristic makes Gel batteries a wise choice for backup power systems or vehicles that spend a lot of time in storage.
Extra Safe and Durable
Because the electrolyte is locked into a gel, there’s little chance of leaks, spills, or corrosion.
This attribute makes gel batteries safer in sensitive environments and more reliable if the battery gets jostled or tilted.
Things to Keep in Mind
While there are many benefits for gel batteries there are a few characteristics you need to keep in mind, which include:
Not Built for Engine Starts
Gel batteries don’t handle high current bursts well.
Most are rated much lower in CCA than AGMs, often under 400 amps. This means they’re not the best choice if your main goal is to start a car or truck engine.
Picky About Charging
They need a very controlled charging profile. Overcharging can cause gas bubbles to form in the gel, leading to permanent damage.
If you use one, make sure your charger is set up specifically for Gel batteries.
More Expensive
Expect to pay more up front than you would for an AGM or traditional flooded battery.
Less Common and Heavier
They’re not as widely available in auto parts stores, and they tend to weigh more, which might matter in some vehicle setups.
Which One Will You Choose?
If you’re still unsure which battery suits your needs more, you can always ask a professional at one of our many battery stockists, or convenient SABAT Battery Xpress outlets.