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5 Battery Types Explained - Flooded, Sealed, AGM, Gel, & Lithium

With all the different kinds of batteries on the market, choosing the right type for your application can be difficult. We recommend you take a few moments to learn more about the most common types of batteries:

  1. Flooded Batteries
  2. Maintenance Free / SLA / VRLA Batteries
  3. AGM Batteries
  4. GEL Batteries
  5. Lithium Batteries

1. Flooded Batteries

This is the traditional engine start, tractor, or deep cycle-style battery. The liquid electrolyte is free to move in the cell compartment. The user can access the individual cells and add distilled water to prevent the battery from drying out.

For a 12v flooded battery, the typical absorption voltage ranges from 14.4 to 14.9 volts; the typical float voltage ranges from 13.1 to 13.4 volts.

Flooded batteries are common and found in many applications, such as automotive starting batteries, motorcycle batteries, ATV batteries, golf cart batteries, and flooded batteries for solar and emergency backup systems.

2. Maintenance Free / SLA / VRLA Batteries*

These are variations of a flooded battery in that they all contain liquid acid. However, unlike flooded, the caps are permanently attached to the battery, and there is never a need to add water.

The manufacturer ensures enough electrolytes have been added to the battery to sustain the battery under normal use throughout the battery warranty period. Even though the user cannot access the cell compartments, the internal structure is basically the same as a flooded battery.

For this type of battery, the typical absorption voltage ranges from 14.2 to 14.7 volts; the typical float voltage ranges from 13.1 to 13.4 volts.

While you can find deep-cycle versions on the market, we recommend avoiding them unless you use a smart charger. Using a bulk or non-microprocessor automatic charger can cause the battery to heat up, causing the electrolyte to evaporate more quickly.

Maintenance-free batteries are very popular for engine starting and limited dual-purpose battery applications. SLA and VRLA batteries are typically found in applications such as UPS systems, medical mobility wheelchair / scooters batteries and toy and alarm batteries.

*Glossary Terms:

  • Maintenance Free = Permanently attached cell caps
  • SLA = Sealed Lead Acid
  • VRLA = Valve Regulated Lead Acid

3. AGM Batteries

The Absorbed Glass Mat construction allows the electrolyte to be suspended within the fiberglass matting surrounding the lead plates. In theory, this enhances both the discharge and recharge efficiency. The AGM batteries are a variant of Sealed VRLA batteries, just a more advanced design. Popular usage includes high-performance engine starting, power sports, deep cycle, solar, and storage batteries.

For this type of battery, the typical absorption voltage ranges from 14.4 to 15.0 volts; the typical float voltage ranges from 13.2 to 13.6 volts.

AGM batteries are common and found in many applications, such as RV batteries, boat batteries, motorcycle batteries, ATV batteries, and UPS & Telecom batteries for generators.

4. GEL Batteries

The Gel Cell Battery is designed not to gas during charging and is similar to the AGM, where they can be used on their side or standing up.

The electrolyte in a gel cell battery has a silica additive that causes it to set up or stiffen. Because of this, the recharge voltages are often lower than the other lead acid batteries to prevent the gel electrolyte from liquefying.

One of the most significant benefits of gel batteries is they tolerate excessive discharge and high heat applications a lot better than your flooded or AGM battery. Gel batteries have a slower chemical reaction than AGM or flooded batteries, so they do not sulfate as fast, making them ideal for VERY DEEP cycle applications.

Battery chargers with gel profile will have information either on the unit, or in the manual, about gel compatibility.

For this type of battery, the typical absorption voltage ranges from 14.0 to 14.2 volts; the typical float voltage ranges from 13.1 to 13.3 volts.

Note about Gel Batteries: It is common for individuals to assume they have a gel battery when they see their battery is marked sealed or maintenance-free. Much like one would use Kleenex when referring to facial tissue or "Xerox" when referring to a copy machine

Our experience tells us that 9 out of 10 times, the assumed gel battery ends up being a maintenance-free VRLA or AGM-style battery. So, be very careful when choosing a charger, and know we are more than happy to help!

Learn more about the differences between a gel cell vs an AGM battery.

Gel batteries are not as common as AGM batteries but are often found in deep discharge situations, such as wheelchairs and medical mobility batteries.

5. Lithium Batteries

Lithium batteries, sometimes marketed as lithium-ion or LifePO4 batteries, are now being seen in starting and deep-cycle applications.

For starting purposes, they typically have much higher cranking abilities than their lead-acid equivalent but are only 1/3 of the capacity of what they replace. A key benefit is their high-cranking and lightweight design, making them ideal for use in motorcycle and power sport racing applications.

Deep-cycle lithium batteries typically weigh about half of the lead acid battery they are meant to replace and excel in cycle life. A basic lead acid battery's cycle life at 50% depth of discharge can range between 500 and 1000 cycles, depending on the chemistry and quality of the battery. In comparison, a lithium battery has 2000+ cycles depending on the depth of discharge! With some lasting well over 5000+ when discharged less!

While lithium has a considerable upside in terms of cycle life, standardization in terms of charging would be its downside. Since the batteries are relatively new to the market, there doesn’t seem to be much standardization between manufacturers. This means much attention must be paid when choosing the correct charger. In many cases, you must verify that the charger’s output voltage and amperage fall within the battery’s specifications.

While not standardized, most 12v lithium batteries typically accept an absorption voltage between 14.0 and 14.7 volts; the typical float voltage ranges from 13.6 to 13.8 volts.

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