Understanding Sealed Lead Acid Batteries (SLA): Sizes, Uses, and Terminal Types

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In this guide, you'll get a clear breakdown of sealed lead acid batteries, what they are, how they’re used, and what to look for when choosing the right replacement for your equipment. Whether you're powering emergency lighting, a UPS system, or a mobility device, understanding the basic differences in SLA battery sizes and terminals can help ensure a smooth replacement process.

Sealed lead acid batteries are often confused with gel cell batteries, but the two are not the same. While both are sealed and maintenance-free, gel cells use a thickened gel electrolyte. SLA batteries, on the other hand, typically use AGM (Absorbent Glass Mat) technology. This means the acid is absorbed into fiberglass mats between the lead plates, eliminating free-flowing liquid and making them safer, cleaner, and easier to handle.

You might see AGM and SLA used interchangeably. Generally, AGM is used when referring to larger batteries, such as those in vehicles, while SLA refers to smaller versions used in indoor devices. Internally, they function the same way.

SLA batteries come in several sizes depending on the application. A 6V 5Ah battery is commonly used in emergency lighting systems and seasonal equipment. These compact batteries are reliable and widely used during the fall for systems like RoboDucts.

A 12V 8Ah battery is frequently used in smaller uninterruptible power supplies (UPS) like the ones found under office desks. While these batteries may appear the same on the outside, they can have different terminal types, specifically F1 (T1) or F2 (T2). The difference comes down to terminal width:

• F1 or T1 = 0.187 inches (about 3/16 inch)

• F2 or T2 = 0.25 inches (1/4 inch)

This small difference is important when ordering a replacement because the terminal must match the connector on your device. Always check the terminal type on your old battery before purchasing a new one.

Larger batteries, like the 12V 22Ah model, are commonly used in jump-start boxes. These portable units rely on higher capacity batteries that can provide strong bursts of power. This battery may come with a variety of terminal options, including internal threaded terminals, lug terminals with bolts, or flag terminals. Each version is designed for a specific connection type, so knowing what your device requires is key.

Another commonly used battery is the 12V 35Ah, which is the same physical size as a garden tractor battery. This battery is most often used in mobility scooters and wheelchairs. With a higher amp-hour rating, it offers longer run times and consistent power for individuals relying on mobility equipment throughout the day.

Despite the range of sizes and terminal types, all of these batteries share a common internal structure. They use lead acid chemistry with the acid held safely inside the separator material. This design makes them completely sealed and leak-proof. Even if the outer casing cracks, these batteries will not leak acid. They are also equipped with pressure relief valves to prevent internal pressure buildup, offering a safe and maintenance-free solution across applications.

Before placing an order, be sure to check a few key details:

• Voltage (V)
• Amp hour rating (Ah)
• Terminal type (F1, F2, threaded, lug, or flag)
• Physical size and fit

These details can be found directly on your current battery or in your device manual. Matching them accurately will ensure your replacement battery works as expected.

If you're ready to order or need help finding the right SLA battery for your system, visit plpbattery.com or call 800-642-3451. A proper fit starts with the right information, and PLP Battery Supply is here to help.