Deep Cycle Batteries: Comparing Lead-Acid and Lithium-Ion Batteries

If you’re considering investing in deep cycle batteries, it’s essential to understand what they are and how they work.

You also need to know the differences between lead-acid and lithium-ion deep cycle batteries.

In this article, we explain:

• what deep cycle batteries are
• the types of deep cycle batteries
• uses of deep cycle batteries
• key differences between lead acid and lithium-ion batteries
• REVOV’s deep cycle batteries.

What are deep cycle batteries?

Deep cycles batteries are designed to produce steady power output over an extended period of time.

Inevitably, this discharges a battery significantly. It must then be recharged to complete a cycle.

A regular car battery, in contrast, is designed to provide a momentary burst of energy – enough to get your car started. It’s not designed to be “cycled”, but is kept fully charged at all times.

Types of deep cycle batteries

The deep cycle function applies to both lead-acid and lithium-ion batteries.

Lead-acid batteries are either flooded cell or sealed lead-acid batteries. Sealed lead-acid batteries are either absorbent glass mat (AGM) or gel cell batteries.

The main uses of deep cycle batteries

Deep cycle batteries can be used for any application that requires continuous power for an extended period.

In South Africa, they’re increasingly used for off-grid and backup solar energy storage solutions. Other uses include:

• uninterrupted power supply (UPS) backup technology and emergency lighting
• wheelchairs, scooters, golf carts, RVs
• marine trolling motor and navigational devices.

Lead-acid versus lithium-ion batteries: key differences

Each deep cycle battery type has its advantages and disadvantages.

Initially, lead-acid batteries are less expensive than lithium-ion batteries. However, lithium-ion batteries offer longer lifespan, reliability, better performance and efficiency.

When you compare lead-acid and lithium-ion batteries, it’s not just price to consider. There are a range of key differences, from capacity to charging time, depth of discharge to delivery.

Battery capacity

A battery’s capacity is a measure of how much energy can be stored (and eventually discharged) by the battery.

Capacity varies between models and manufacturers, but lithium-ion batteries are known to have a significantly higher energy density than lead-acid batteries.

Lithium-ion batteries commonly provide 20 to 50% more usable capacity and operational time, depending on the discharge current.

This means more energy can be stored in a lithium-ion battery using the same physical space. This means you can discharge more energy and power more appliances for more time.

Depth of discharge

Depth of discharge (DoD) determines how much of the battery can be discharged safely compared to its original capacity before it must be recharged.

Lead-acid batteries have a considerably lower DoD, 50%, compared to more than 85% for lithium-ion batteries.

This means you have to recharge lead-acid batteries more often. Lithium-ion batteries last longer before they need to be recharged.

Charging time

This is the time it takes to recharge a battery. The lower the number, the less time it takes. The actual time depends on several factors, such as the battery capacity, age and battery charger.

Lithium-ion batteries charge up to four times faster than lead-acid batteries, which are notoriously slow to charge. On average, these are the charging times in hours:

• lithium-ion battery (2 – 3)
• AGM battery (5)
• gel battery (5 – 10)
• flooded lead acid battery (8 – 16).

Efficiency

Battery efficiency is important to compare. Most lithium-ion batteries are 95% efficient or more. Lead-acid batteries are closer to 80%.

Higher efficiency batteries charge faster and higher effective battery capacity.

Constant power delivery

A lithium-ion battery delivers the same amount of power throughout the entire discharge cycle.

A lead-acid battery’s power starts out strong but dissipates. Imagine how a torch dims as the battery runs out.

Lifespan

Over time and with use, batteries degrade and become less effective. Discharging and recharging a battery counts as one cycle.

Lithium-ion batteries last for considerably more cycles than lead-acid batteries – up to 5,000 cycles – leading to a longer lifespan.

They last for more than 10 years, compared to around three to five for lead-acid batteries. In fact, a lithium-ion battery could last as long as 20 years.

Battery weight and size

Lead-acid batteries are large and incredibly heavy.

On average, lithium-ion batteries are 55% lighter and much smaller, so they’re easier to house.

Installation

There are no installation requirements for lithium-ion batteries, which are individually sealed and do not need venting. They can, if necessary, be installed on their side or upside down.

Lead acid batteries must never be installed in an inverted position. This is to prevent the risk of leaking gas.

Temperature tolerance

A battery’s chemistry and therefore capacity and efficiency are impacted by temperature.

Lithium-ion batteries easily outperform lead-acid in extreme temperatures. A lithium-ion battery at 55º C has twice the lifecycle of a lead-acid battery at room temperature.

REVOV’s deep cycle lithium batteries can charge at temperatures from zero to 45° C. They can discharge at temperatures from -10° to 45° C, so can be used in intense weather conditions.

Maintenance

Lithium-ion batteries do not require any active maintenance to extend their service life.

Lead-acid batteries need special maintenance, or their lifespan will be decreased further.

Deep cycle batteries from REVOV

REVOV’s deep cycle lithium-ion batteries use lithium iron phosphate technology.

We have a range of deep cycle batteries for sale,  including LiFe and 2nd LiFe products, which are batteries that use repurposed cells from electric vehicles batteries.

These are some of our most popular and cost-effective deep-cycle batteries.

REVOV 2nd LiFe R100

51.2V 100Ah (5.12 kWh)

Our REVOV R100 is our most popular lithium iron battery. It offers superior performance at a cost-effective price, with 5 kWh capacity, a depth of discharge up to 100% and a 10-year warranty.

REVOV LiFe C8

51.2V 220Ah (11.2 kWh)

These high-quality lithium iron batteries offer the best cost per cycle in South Africa for a 1st Life deep cycle lithium battery. It has a 10-year or 3,500 cycle warranty.

REVOV 2nd LiFe R9 Lithium Iron Battery

REVOV’s R9 is a high-quality 220Ah & 250Ah 2nd Life lithium iron battery that’s ideal for solar and off-grid applications. It offers exceptional performance and a lifespan of more than 10 years.