The cheapest backup power setups for running your PC during load-shedding

Load-shedding recently returned to South Africa, which means that many people may need to buy backup electricity solutions to keep important electronics running while the power is out.

This requirement has been exacerbated by the increased prevalence of working from home due to the COVID-19 pandemic.

Having a laptop which is capable of running for a couple of hours on its battery provides a possible back-up option for work or entertainment, but many households may only have access to desktop PCs.

Additionally, gamers with desktop gaming PCs would need a powerful backup system for extended periods of gaming during load-shedding.

Uninterrupted Power Supplies (UPSs) are capable of providing sufficient power for a few minutes of operation, although they are not capable of or intended for use over multiple hours.

Among the best solutions available on the market for providing backup power for this particular scenario is so-called “power trolleys” – which combine an inverter and battery system in a convenient, portable all-in-one solution.

These trolleys come with larger, long-run batteries which work similarly to a UPS setup.

How much power you need

To figure out which power trolley you would require, you must calculate the power consumption of your PC.

Blue Nova Energy – a provider of backup power solutions in South Africa – explained that power rating and consumption for PCs can vary fairly widely.

While an entry-level PC power supply will be rated between 200W to 250W, high-end PCs like gaming desktops can use upwards of 500W, depending on the exact components used.

To determine the amount of power your computer will draw, you must add the power consumption of all the components – including the motherboard, graphics card, memory, and storage devices together.

There are various online power supply calculators available, including one from Newegg, which allows you to calculate the estimated power consumption of your particular desktop build.

Monitors will also need their own power supply, which is typically around 30W for a standard 17-inch LCD panel.

Additionally, if you want your router to stay powered, this would on average require a further 20W.

The total power needed for an entry-level computer can therefore be calculated as follows: 250W + 30W + 20W = 300W.

If you want to keep this computer powered on throughout load-shedding, the total standby capacity required would then be 600Wh for two hours, while a four-hour load-shedding period would need 1,200Wh (1.2kWh).

Limitations

It should be noted that it is not ideal to discharge power trolley batteries beyond a certain threshold.

Most batteries currently used in power trolleys are lead-acid, which means that although they are capable of deep-cycling, this is not optimal.

Repeatedly running the batteries below 50% capacity will severely impact their lifetime and may require you to replace them every few months.

For example, while a 1,200 VA Inverter with 100Ah battery will be capable of running a 300W setup for four hours, it would consume 1,200W of power during this time.

Ideally, the solution should be capable of offering double the required capacity to achieve optimal battery life.

Options compared

The table below details backup power solutions for varying levels of demand.

The red figure indicates the maximum power time, while the green figure indicates the recommended maximum use time.

Power trolleys for PCs
Power trolley Capacity Entry-level uptime (300W) Mid-level uptime (500W) High-demand uptime (750W) Price

Mecer 1200VA (720W) Inverter + 100Ah battery

1,400Wh 4 hours

2 hours

2-3 hours

1 hour 30 minutes

Under 2 hours R5,500
Ellies 1200VA (720W) UPS Power Inverter + 100Ah battery 1,400Wh 4 hours

2 hours

2-3 hours

1 hour 30 minutes

Under 2 hours R6,990
Mecer 1200VA (720W) Inverter + 2 x 100Ah batteries 2,400Wh 8 hours

4 hours

4-5 hours

2 hours

Under 2 hours R8,795
Smart Power Trolley 1KVA (600W) Pure Sine Inverter/UPS/Charger/Solar + 100Ah gel battery 1,400Wh 4 hours 2-3 hours n/a (beyond rated power output) R8,990
Mecer 2400VA (1,440W) Inverter + 2 x 100Ah batteries 2,400Wh 8 hours

4 hours

4-5 hours

2 hours

3 hours

1 hour 30 minutes

R8,995

Ellies 2400VA (1,440W) UPS Power Inverter + 2 x 100Ah batteries

2,400Wh 8 hours

4 hours

4-5 hours 

2 hours

3 hours 

1 hour 30 minutes

R10,990

Now read: Eskom confirms electricity price increases for South Africa

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The cheapest backup power setups for running your PC during load-shedding