Eskom will implement Stage 4 load-shedding from 16:00 on Thursday, 3 August 2022, and South Africans can get a backup power trolley to last the duration of a two-and-a-half-hour power cut for as little as R4,995.
MyBroadband looked for affordable backup trolleys that could power a selection of electrical equipment through a bout of Stage 4 load-shedding.
Our requirements were to power a Wi-Fi router, a desktop PC, a couple of LED lights, a TV, and a DStv decoder through a two-and-a-half-hour power cut.
According to Energy Use Calculator, the average Wi-Fi router draws around 6W. This works out to 15Wh of electricity usage during a bout of Stage 2 load-shedding.
The average 55-inch TV draws less than 60W of electricity or 150Wh over two-and-a-half hours.
We selected 5W-rated LED lights for our analysis. Two 5W LED bulbs will consume around 25Wh during a bout of Stage 4 load-shedding.
The power consumption of DStv decoders varies depending on the model. The DStv Explora uses a maximum of 45W, which means it will use 112.5Wh over two-and-a-half hours.
Similarly, the power consumption of a desktop PC varies based on its components. According to Northwestern University’s IT department, the average power usage of a desktop PC is around 150W, or 375Wh, during a stint of Stage 2 power cuts.
|Power usage over 2.5 hours|
|Two LED lights||25.00Wh|
Based on the usage figures of the electrical equipment above, the backup power system would need the capacity to store at least 680Wh of power.
However, it is important to consider that you may need to increase the capacity if you use lead-acid or gel batteries.
More-affordable power trolleys typically come with lead-acid batteries, and while some have deep-cycle capabilities, they cannot discharge fully without reducing their lifespan.
This means that the batteries in such trolleys typically only last for a couple of hundred cycles before their capacity is reduced significantly, often requiring replacement.
They also commonly only have a depth-of-discharge (DoD) of around 50%, meaning you might have to double the capacity required for lead-acid batteries.
A typical 100Ah 12V lead-acid battery will have a theoretical maximum capacity of 1,200Wh, but one should ideally never let it drop below 600Wh charge to prevent shortening the battery’s lifespan.
Gel batteries have a slightly better lifespan than lead-acid alternatives, but they cannot match the longevity of lithium-ion batteries.
Lithium-ion batteries generally have a DoD of 80% to 90%, meaning they have a greater capacity than similarly-specced lead-acid batteries.
It is worth noting that lithium-ion batteries are significantly more expensive per Wh than the alternatives. However, they typically last for more than 1,000 cycles, meaning they ultimately save you money.