The Inverter Trap

With load shedding set to continue for the foreseeable future, many people are looking at inverters and other power backup system to keep Wifi, Streaming boxes and TV’s running while ESKOM treats us like mushrooms.

But, there are some very important facts about inverters you need to know before you buy one and most sales people or online sites DON’T give this information to potential clients.

The inverters I’m referring to are the portable plug n’play products you can buy from Builders/Makro and online. These use power the grid to charge the battery and then you connect your various devices to it when the power goes out.

What Batteries Do Inverters Use

Most of these units use lead-acid batteries, like lead-calcium or gel batteries and while these are cheaper than lithium-ion batteries, you do need to know how they run to avoid your batteries losing power and performance.

  1. You need to know that you should avoid running your battery below 50% discharge as this will slowly start decrease it’s performance over time.
  2. Lithium-ion batteries can discharge to 80% or more without losing performance on their cycles, but lead-acid batteries will start to underperform fairly quickly when they are run down to lower than 50%.

This means that if you have a four hour outage, you should avoid discharging your battery on the inverter below half .

Most inverters display the battery level like your mobile phone does, so keep an eye on it and make sure it doesn’t get below two bars (if you have four bars).

If you see that the battery level is dropping fast, then unplug your larger devices like TV’s and laptop chargers.

A laptop charger can use around 45W , while TV’s ( even the modern ones) can use around 100W to 200W per hour.

How Can I Tell How Long I Can Run My Inverter For

To make this easy, lets make the inverter a 1000W unit.

This means that the inverter can deliver 1000W of power , so to calculate how long this battery would last, you need to know what the wattage of each connnected device is and then divide that by the 1000W to get the number of hours you can use your devices for.

For this example, we’ll take a laptop charger at 50W, a TV at 150W , a WIFI modem at 20W, TV box at 20W and ad 2 X LED lamp at 5W each.

To find the wattage on any device, simply look at the device label and this will give you the wattage in W.

For the example above, we can see that the total power is 250W.

If we take that and divide it by 1000W, you get 4 hours. So , your 1000W inverter can run all of those devices for four hours.

But remember, that depleting the battery under 50% will cause it to lose performance quickly and mean you will have replace it sooner than you’d like.

So, for the example above, try and aim to use the devices for half the time – or disconnect the higher wattage devices like the TV to preserve your battery life.

If we look at the wattages without the TV, it drops down to just 100W and this means 10 hours of power from your inverter or 5 hours if you only use 50% of the capacity.

Read more below.

Lead-acid batteries can only be discharged up to 50% before irreversible damage occurs.

By having a little discipline and making sure all devices are fully charged before load shedding hits, you can keep your inverter battery in good shape and it will give you good service for a few years before you need to replace it- and hopefully by that time, we will have graphene batteries and lithium-ion will be much cheaper!

And that’s The Joburg Truth!

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