Common load-shedding battery mistakes to avoid
Buying the wrong backup battery to carry you through load-shedding could end up causing you more headaches than Eskom.
While there are numerous options on the South African market these days, there is a proliferation of cheap products and fly-by-nights that won’t last and could cost you dearly in the long run.
MyBroadband spoke to Rubicon’s head of energy and e-mobility, Greg Blandford, and Solar Advice director, Neil Berrow, to learn more about what consumers should focus on when considering their options.
Blandford said one of the big problems was a minefield of suppliers and brands to choose from, but that pricing was typically a good indicator of the performance you should expect.
“In general, pricing for batteries is related to the quality of the materials used and the type of battery chemistry. So you get what you pay for,” Blandford said.
There are three main types of batteries sold for backup purposes in South Africa — the cheaper lead-acid and gel variants, and more expensive lithium types.
The big difference between lead or gel batteries and lithium batteries is their depth-of-discharge (DoD).
“Lead and gel are similar in performance, with gel having a slightly longer lifespan and slightly higher price point,” Blandford explained.
“They can only typically be discharged by 30% and maybe to 50% on high-end versions, but the more the discharge, the shorter the lifespan.”
“Lithium, on the other hand, can be discharged to 90 or 100%, in some cases, with no negative effects on the lifespan.”
In addition, lithium offers around 7,000 to 10,000 discharge cycles, much more than the 1,000 provided by the best deep-cycle lead-acid batteries.
The image below illustrates the key differences in capacity capabilities of lead-acid and lithium-ion.
It’s easy to see why consumers often opt for lead-acid or gel.
On Takealot, you can buy a 100Ah lead-acid battery for R3,445, while a lithium-ion battery with equivalent capacity will cost you around R6,000.
However, Blandford stated that the 10-year cost of lead-acid and gel would be greater than lithium-ion.
“The difference with lithium is that you pay for the lifespan upfront. With lead-acid, you pay less upfront but replace multiple times over the same period, making it more expensive in the long term.”
Berrow also pointed out that lead-acid backup systems can end up getting damaged because it’s easy to overload them.
“A lot of the time going for lead-acid batteries is not for long-term use past four years. Also, you can’t really expand on them, so you have to replace the whole bank every time.”
Berrow said that deep-cycle lead-acid or gel batteries were only worth the money if you are looking for a solution that will last three to four years and are on a tight budget.
Blandford stated these batteries could be suitable in cases where grid outages only occurred once a day.
“As soon as there are multiple occurrences of load-shedding in a day, then the life of lead batteries is affected.”
Furthermore, lead-acid batteries should be checked periodically for a charge to avoid the battery running flat and reducing the lifespan.
“Lithium is still the best option for backup power and needs little or no maintenance,” Blandford said.
The Tesla Powerwall is a high-capacity lithium-ion battery for backup power.
Berrow also advised those looking for a long-term solution to invest in lithium-ion batteries, as they lasted longer, were safer, more robust, expandable, and offered longer warranties.
When considering lithium options, he recommended the following minimum specifications.
- Cycles — 6,000 or more
- Depth-of-discharge — At least 80%
- Discharge rate — 0.5C or higher
- Warranty — 10 years
In addition, they should be compatible with inverters that can convert their energy into useable electricity.
A single cycle consists of a discharge and recharge. Therefore, a 6,000 cycle battery will last for 6,000 days or more than 16 years, assuming one cycle for each day.
Berrow also explained that running a kettle, microwave or pump on the battery will require a discharge rate of at least 1C or the capacity to be large enough to handle power spikes.
The battery maker could also be an important indicator of expected performance.
Below are the various brands recommended by Berrow and Blandford.
Lithium-ion brands recommended by Berrow
- Fusion Solar
- Dyness
- Alpha
- Pylontech
- Batterich
- Blue Nova
Lithium-ion brands recommended by Blandford
- Synapse Lithium
- Pylontech
- Weco
- Tesla
- Freedom Won
- Solar MD
- Hubble
Lead-acid brands recommended by Blandford
- Narada
- Enersys
- Trojan
- Ritar
- Royal
- Vision
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