Important information for people buying batteries in South Africa

While the lithium-ion (Li-ion) battery has become the undisputed king of energy storage in South Africa, many people may not be aware that not all these batteries are made equally.

Depending on the various aspects of the battery’s design — including the materials used for its cathode or anode — it may offer very different performance and safety characteristics.

Before load-shedding became a regular occurrence, common backup power systems, such as those used for gate motors, alarm systems, and desktop PCs, only needed to last a few minutes or hours.

In those years, lead-acid or gel batteries were suitable for these applications.

Because power outages were few and infrequent, users were not too bothered that they could only get about 150 to 200 cycles out of these batteries before they needed to be replaced.

As load-shedding became more severe, the business case for more expensive lithium-ion quickly became evident.

Lithium-ion batteries boasted well over three times the cycles of lead acid or gel batteries while also being suitable for deeper discharging.

Crunching the numbers in the late 2010s would quickly reveal that the frequency of load-shedding meant it would be far more expensive to keep replacing lead acid or gel batteries than to use lithium-ion.

Lithium-ion prices have plummeted over time as demand for the technology increased due to its usefulness for storing renewable power and energy to run electric vehicles (EVs).

Among the first iterations of lithium-ion batteries used for backup in South Africa were lithium ternary batteries.

These batteries have cathodes of nickel, manganese, and cobalt (NMC) or nickel, cobalt, and aluminium (NCA).

Depending on the specific model, lithium ternary batteries typically offer 500 to 1,000 full charge-and-discharge cycles before their capacity starts degrading below 80%.

Lithitum ternary batteries have high energy densities, making them ideal for applications where space and weight are a major factor — like in mobile devices or EVs.

While there have been many warnings regarding the safety of these batteries, due to their potential for thermal runaway, they do not commonly explode or catch fire unless they are abused.

This could include exposing the batteries to very high or very low temperatures or charging and discharging them too quickly.

That is why it is important to have your battery installed by a reputable and qualified electrician with high-quality components.

The bulkier but safer option

In recent years, lithium ternary batteries have largely been sidelined in stationary backup storage and replaced with lithium iron phosphate LiFePO4 (also called LFP) as the preferred option.

While also a type of lithium-ion battery, LiFePO4 batteries use iron phosphate as a cathode material.

LiFePO4 has a lower energy density and lower charge and discharge efficiency than lithium ternary packs.

However, the use of iron makes for a much stabler reaction than the NMC or NCA elements, making these batteries much safer.

Although they can still produce fires if damaged, they do not produce violent explosions or enter a thermal runaway chain reaction.

They are also much easier to extinguish as the burning of their components does not produce oxygen, which lithium ternary batteries do.

In addition, LiFePO4 batteries have more lifecycles than lithium ternary batteries, typically 3,000 to 6,000 before reaching 80% of their original capacity.

Due to its improved safety and longer life, LiFePO4 has become the dominant type of lithium-ion battery used by solar power installers and the main type of battery assembled in South African plants.

For the big guns

The last type of lithium-ion battery to be aware of is the lithium titanate (LTO) pack.

Despite being one of the oldest types of lithium-ion batteries, lithium titanate is perhaps the least familiar.

These batteries use lithium titanate nanocrystals instead of carbon on the surface of their anodes. 

That increases the surface area of the anode to roughly 100 square meters per gram, compared with three square meters per gram for carbon.

This change enables electrons to enter and exit the anode faster, ideal for charging and discharging batteries quickly.

Lithium-titanate cells can also last longer than conventional lithium-ion and LiFePO4 batteries and are the safest type of lithium-ion battery.

Below is a video of South African battery company Mega-Titan shooting high-velocity incendiary rounds at an LTO battery.

Even after three shots, the battery continued delivering power to a load and did not catch fire.

However, there is a drawback to these benefits — much lower energy density.

Lithium titanate batteries are heavy and take up more space per watt-hour, making them less suitable for use in confined spaces or devices with limited space.

In general, they are used in applications with high instantaneous charging or discharging requirements, including utility-scale grid storage and military applications.

The table below summarises the key differences between the three main types of lithium-ion batteries.