Types of Lead Acid Batteries

There are many types of lead acid batteries which come in various shapes, designs, and sizes. They are immensely popular because they are robust and rechargeable. Most of them require little maintenance and with proper care, can serve you for a long time. In the section below, we shall look at different types of batteries as well as their advantage and disadvantages.

Lead Acid Battery

1)   Starting Lighting & Ignition (SLI)

SLI batteries are designed to crank engines with high-power lasting for a second. They use electrode plates strengthened with either lead calcium (sealed configuration) or lead antimony (flooded configuration). Unlike deep cycle batteries, they have many thin plates running parallel. This enables them to achieve a low resistance with high surface area. Compared to other types of lead-acid batteries, they have high charge and discharge rates.

Typical of automotive batteries, they are designed to be charged when ignition starts and lose charge once the vehicle starts. 2-5% of the charge is replaced by the vehicle’s alternator. Often, they are not supposed to be discharged below 50% depth. Discharging them below this level will eventually damage the plates and shorten the battery’s life. A typical starting battery has a lifespan of between 3 to 12 months.

Generally, SLI batteries have a good operational life in shallow-cycle conditions but dismal lifetime under deep cycling. Since they are not optimized for renewable energy systems, they are not recommended for use in PV system. Most starter batteries are rated with RS or Ah which indicates their energy storage capability. They also have CCA (cold cranking amps) which signify the amount of current they can produce at cold temperatures.

Application:

 SLI batteries are normally used in automotive applications to start cars and boats. Owing to their size, they can deliver huge bursts of current for a short time than deep-cycle batteries.

 Pros

• reasonably priced
• low internal resistance
• excellent pulse discharge capabilities

Cons

• limited charge rate
• Performs poorly in deep applications

2) Vented Batteries/Wet Cell

Vented cell batteries are one of the oldest types of lead acid batteries. They are referred to as wet cell because they produce current using the chemical reactions between electrodes and the liquid electrolyte. These batteries are available in two designs; serviceable and maintenance free. The majority of these batteries use flooded cell technology. And like other lead batteries, have lead plates which are immersed in a corrosive electrolyte solution. These batteries come with valves which releases pressure to prevent gas buildup which could rupture the cell case. What makes them attractive is that they are lighter in weight compared to AGM batteries and less prone to damage through overcharging.

Wet cell batteries have two kinds of plates; anodes and cathodes. Anodes are attached to the negative terminal of the battery while the cathode to the positive terminal. Since they contain liquid electrolyte in unsealed containers, they ought to be kept in an upright position in a well-ventilated room. Wet cell batteries require routine monitoring and topping with distilled water.

Application:

Wet cell batteries are used in various applications such as electric tools, cellphone towers, and aviation.

Pros

• reasonably priced
• easy to troubleshoot
• excellent pulse discharge capabilities

Cons

• limited charge rate
• require regular topping
• Performs poorly in deep applications

3) Deep Cycle

Deep cycle batteries are primarily designed to discharge most of its capacity (as much as 80%). This allows them to maintain a cycle life of thousand cycles. Unlike starting batteries, they deliver short but huge bursts of currents. At any given time, they discharge between 45-75% of their charge capacity. The discharge varies from one manufacturer to another. While most batteries can be cycled to 20%, the recommended cycle should be at least 50%.

What makes them different from the other types of lead acid batteries is that they have thicker and solid lead plates. This gives them a small surface area and less instant power than starting batteries. The thick and strong plates also prevent them from warping due to excessive heat when charging. Typical of deep cycle batteries, they also have lower cranking amps compared to normal starting batteries. And while they can be cycled down up to 20% charge it’s recommended that users keep the average at 50% discharge. Most L-16 type deep cycle batteries have a life span of 4-8 years.

You can prolong the life of deep-cycle lead acid batteries in a variety of ways including proactively preventing corrosion and keeping them at an ideal temperature.

Application:

Since they deliver a lower but steady burst of power for a long period, deep-cycle batteries are widely used to power marine applications such as boats, fork lift trucks, and golf buggies. They are also frequently used in power accessories such as winches and trolling motors which need to be fully discharged before charging. When used for automotive applications, they ought to be oversized so as to compensate for their lower capacity to carry current.

Pros

• Dual purpose
• Last for thousands of cycles

Cons

• Lower cranking amps

4) Sealed Batteries/VRLA

Sealed lead acid (SLA) batteries contain absorbent microfibre glass mat that separate plates. The glass matt are meant to immobilize electrolyte. Although they are referred as  sealed, they contain vents that let out gas during charging. Typical batteries produce six volts that provide prolonged cycling service.

Just like all types of lead acid batteries, VRLA batteries release hydrogen from the negative plate and oxygen from the positive terminal while charging. They are fitted with pressure relief valves which open when the pressure from hydrogen gas starts building up. The valve action lets the gas escape and consequently reduces the capacity of the battery.

When using sealed batteries, proper care should be taken to prevent rapid charging and short circuits. The best way to charge them efficiently is to use constant-voltage However, you can still float charge them at 2.35 volts in room temperature.

Application:

SLA batteries are used to power a number of consumer products and power tools. You’re more likely to see these batteries powering electric drills and electric starters for kids’ toys. Additionally, they are commonly used in deep discharge applications where they power electric vehicles, golf cars, scooters, and sailboats.

On the other hand, valve regulated lead acid batteries come with pressure valves that release gas when it builds up to extreme levels. Their electrolyte design reduces gassing and impedes oxygen and hydrogen release to the atmosphere.

Pros

• charges much faster
• higher performance under heavy load
• spill/leak free
• works fine in cold conditions
• vents less gas

Cons

• high-self discharge rate
• Long charging hours