What Is An Sla Battery? (Sealed Lead Acid Battery)

What Is An Sla Battery? (Sealed Lead Acid Battery)

sla batterty

An SLA battery is a type of rechargeable battery. It's chemistry consists of a liquid acid and grid plates where the current enters and leaves the cell. Sealed Lead Acid Batteries are also known as Valve Regulated Lead Acid or VRLA batteries. They contain safety valves that release gas when overcharged with no outside ventilation required to disperse the gas harmlessly into the atmosphere.

The Sla Battery can be installed in any position due to its non-spillable design, but operationally should remain upright for maximum life expectancy and performance.

Pros of SLA Batteries:

There are many benefits to using an sla battery. Below you will find a list of the pros of these batteries.

  • Leak proof
  • Convenient to use
  • High discharge rate, low self discharge rate.
  • Can be stored for long periods of time, with or without charge.
  • These batteries are 100% recyclable.
  • Universally applied
  • They are maintenance free and will not sulfate or crystallize during long periods of storage.
  • Conventional lead-acid batteries are extremely robust and some even claim that they can last up to 20 years if properly cared for.
  • No Thermal Runaway: The battery cells in AGM batteries maintain a balanced charge at all times and because the recombination reaction is essentially internal to the cell, no gas escapes during normal operation. This provides safety from hazardous conditions created by excessive pressure build up should a case rupture. In addition, should leakage occur from a fractured case, it would be contained within the battery itself eliminating environmental contamination or personal injury from contact with leaking acid.
  • In cold weather, these batteries perform better than traditional batteries.
  • They also hold up to higher temperatures, and resist shock and vibration better than other battery types.
  • More reliable: These batteries can be mounted in virtually any position without fear of leakage or corrosion damage. They are maintenance free and will not sulfate or crystallize during long periods of storage.

Cons of SLA Batteries:

  • Typically not cost effective if the need to replace them every year or two is required. This does depend on application and grid plate design though.
  • Low cycle life (2000 cycles at 80%) when compared to other types such as gel cells that have 3000+cycle life during same use conditions.
  • More complex than a traditional car battery since they require a longer time to recharge and a constant voltage to maintain the same level during discharge. This makes them extremely inefficient in standby mode where energy is concerned.

SLA Battery Safety

SLA type batteries have extremely low self-discharge rate and offer very high discharge characteristics. Temperature compensation is built into the cells preventing thermal runaway which could cause a fire if left unchecked under normal conditions; they will give alarm when exposed to heat beyond acceptable limits, there is no need for an overtemperature protection system (OTS).

What is the difference between SLA, AGM and VRLA batteries?

SLA and VRLA are lead acid batteries based on similar chemistry. An SLA battery is used for new equipment or standby power, whereas VRLA battery is designed for emergency lighting and other applications where the full discharge may be experienced several times each day, so a very high discharge rate capability is needed without damage to the cells. However there are new technologies available which overcome these differences thus creating cross use of the two types of batteries in different application areas. One of them is the AGM battery.

This new, unique type of lead acid battery offers the best features of both SLA and VRLA technologies with no compromises. The AGM battery combines the plate formulation, grid construction and separator technology of an SLA with the recombination process of a VRLA into one cell design to form a hybridized version which has all the benefits associated with each technology i.e., excellent high rate capability similar to SLAs but with true deep cycle capabilities like VRLAs. AGM batteries also exhibit superior performance in cold temperature applications where the use of other types is limited by their inability to deliver adequate power output at low temperatures.

agm batterty

AGM batteries are sometimes called "starved electrolyte" or "dry spill proof" batteries, because the fiberglass mat is only 95% saturated with Sulfuric acid and there is no free liquid electrolyte. AGM batteries rely on the capillary action of the fiberglass mat to draw sufficient electrolyte into the pores of the plates. If an AGM battery has been over-filled or charged too quickly, excess fluid can be spilled out through the safety valves which are located at each cell's peak. Another design feature of these batteries is that they must be kept upright at all times; because if they are ever laid down for an extended period, acid will leak out of the valve and ruin the battery.

The main benefit of using this type of construction in a deep cycle application is that it eliminates water loss due to gassing. This is an important consideration when operating in extremely hot climates, and when the battery may be prone to extended periods of low electrolyte levels due to excessive cycling.

The drawback to this type construction is that if the plates become damaged due to physical abuse or vibration, internal acid spills can completely ruin the battery before it can be noticed. The other major drawback with series construction is that it greatly diminishes battery performance at higher temperatures (above 80°F). Therefore deep cycle applications involving frequent cycling in these conditions should utilize a series/parallel configuration instead.

How to charge an sla battery

Charging an SLA battery is an easy task. You can typically use any standard battery charger for this purpose. The only thing you have to keep in mind is that if it has a setting for gel cell batteries, you should set it to that position instead (most of them do).

A Constant voltage of 13.8Vdc should be adequate to fully charge a 12V SLA battery.

If your charger does not have the gel cell option, chances are an adapter is available. You may need to check with the manufacturer or dealer on this though because not all units will supply the required voltage.

Since SLA batteries contain distilled water, they cannot be charged at temperatures lower than 60°F (16°C) or above 120°F (49°C). Also make sure the room temperature falls within these limits. If outside, do not attempt charging and wait till conditions improve before doing so.

SLA Battery Usage

The SLA battery has many different uses. They are more commonly used in cars, but they are also used in protected applications such as UPS backup systems, spotlights, ATV's, generators, wheelchairs, and mobility scooters. SLA batteries can also be found in motorcycles and some ATVs.

One of the benefits of an SLA battery is that it is maintenance-free. Since there is no need to add water or acid, you will not have to worry about this kind of product deteriorating over time due to lack of attention. In most cases, SLA batteries will come with a two year warranty from the manufacturer. This means if your battery fails or malfunctions before then, you may return it for a refund or replacement at no extra cost to you. While they might seem more expensive initially when compared with other options, their long shelf life makes them a sound investment.


After reading this blog post, you should have a clear understanding of what an SLA battery is and the benefits that come with this product. Their maintenance-free design makes them reliable and cost-effective, while their warranty ensures that they will serve you for years to come.

Buying one will not be a waste of money. Now that you know what the product is and how it can help you, you can make an informed decision about whether or not it is right for your needs. If so, go ahead and purchase one today.

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About Author:

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Hi, I'm Kevin Pommells, a lover of camping and the great outdoors as everyone says nowadays. I'm also a passionate soccer fan and the proud owner of CamperRules.com, a website dedicated to helping campers and outdoor enthusiasts make the most of their adventures. With years of experience exploring the wilderness and a deep love for the sport of soccer, I'm always looking for new ways to combine my two passions and share my knowledge with others. Follow me for tips, tricks, and insights on all things camping and outdoor recreation.

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