Page 23 - Issue 4 2023

TECHNICAL

The rise of the small, portable, outage-

defeating power pack

Continued load shedding has created a market for small reserve power systems that are
capable of keeping essentials running during load shedding. Changed conditions have
led to the development of small, reasonably priced reliable power supplies, that can meet

the basic requirements of a home office and the needs of those who cannot install large
backup power systems.

Staffwriter

he initial small business/home solution response to load shedding was a typical The industry has seen this need
centralised power engineering knee-jerk solution consisting of a large charger/ and has come up with low priced DC
Tinverter (with 1 to 2 kW output) mounted on a trolley containing large lead UPS modules that meet this demand.
acid batteries. This unit offered backup for up to two hours at full load, and was able Equipped with Li-ion batteries and
to power computers, TVs, a few lights, and small appliances for that period. Equipped an output power capacity ranging
with two standard sockets and fixed in one place, these units require extension cords from 30 to 100 W, the units feature
to be run out to various loads around the house or office. twin adjustable DC outputs and will
These “trolley inverters” were fairly high priced. Initially, load shedding took place power the usual fibre/wireless internet
in blocks of four hours at a time, which influenced the size of the system. Initially connection and WiFi router for more
they worked well, but two years down the line there are rumblings that the batteries than two hours (see Figure 1). There
supplied with these large trolley systems were losing capacity, and their suitability was are now a wide range of these units on
being questioned. Li-ion batteries last longer than lead acid cells, but are much more the market and they have proved to be
expensive. very popular.
The advent of Covid changed all this. With many people now working from home, Since some laptop batteries don’t
the need for a power system that would ride through load shedding during the day last for two hours – and some load
became much greater. This changed the basic requirement as lights and TV were not shedding intervals exceed two hours –
required during the day. A further factor was the change of load shedding from four and other small office devices such as
hour blocks to two hour blocks, a period that could be accommodated by printers require an AC feed, a demand
the standard laptop battery.
Other products became available too, such as emergency
lights that didn’t need extra cables and switched over to
emergency power automatically, and a variety of
portable battery powered LED lanterns which could
be carried to wherever needed.
With many people being unable or unwilling to
lay out the cost of a solar PV system, large UPS or
battery storage system, the basic question became
“What is the minimum amount of backup power needed
to ride through load shedding?”
The answer to this is “at least enough to power an internet
connection and a Wi-Fi system”.
The battery in a laptop computer will generally last for two hours, or more, and
mobile phones’ batteries last even longer. Therefore, a power supply that could keep
the Wi-Fi router running would keep a home worker connected through the average
load shedding period. Figure 1: DC internet/Wi-Fi UPS (Gizzu)

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