Battery size calculator

To calculate approximately how big a battery and inverter you require for your power backup needs in Amp-hours (Ah), enter the power of each appliance and the average length of loadshedding time. The first couple of lines are given as an example; just click in the boxes to replace the values with an estimate of your own power consumption.

5 things to look for in power backup system

Here are 5 things you must look for in off the shelf power backup solutions:

1. If it looks home-made, it probably is. The problem with any home-made product is that you get no guarantee, no long term support, no quality connections and no real thought about the components such as cables that work efficiently and use less electricity.

2. Many Inverters on the Market do not perform as well as the manufacturers claim. Make sure the stated Watt capability is true and correct.

Read the small print to make sure the Inverter actually delivers the correct WATTS for what you require. Mention of advanced filtering is a good sign.

3. Only a proper Deep Cycle battery should be used. It has been designed to charge and drain a load over and over. Car batteries are designed for staring (a quick load) they are not designed for been totally drained of power and then charged up again. The incorrect battery will fail, 100% guaranteed.

4. Make sure that the watts are correct for your application. Always take a little bigger than what is actually required. Buy a bigger unit e.g.if you need 1000 Watts then buy an inverter than can deliver 1200 Watts at least. An absolute must is SURGE Watts, on almost every application when you switch on there is a higher surge of power that the Inverter must cope with.

5. The Cables running from the battery to the Inverter must be of a very good quality – the thicker the better. This is very important as a lot of power is used and a lesser quality cable will get hot and can be unsafe. The connectors, joining the cable to the battery must be strong and sound. The contact must be good.

Understanding Backup Power Suppply

Do you know what is important when you’re building or buying a power backup solution for your home or your business?

Learn what the backup power supply options are, what the systems consist of, what equipment to buy when your building your own and what questions to ask when your buying an off the shelf item.

We’ve spoken with engineers and experts in all the fields required to produce a backup power supply system and hand picked products to make available directly to you.

UPS vs Inverter what is the difference

You have the option of a UPS Inverter or a standard Inverter.

UPS Inverter – this can be connected in-line, meaning that it can be connected in such a way that when the power fails the UPS Inverter automatically kicks in without any interruption.

Standard Inverter – this is an off-line system, when the power fails you need to turn the Inverter on.

Once turned on both work the same.

A UPS should not be confused with a standby generator, which does not provide protection from a momentary power interruption and may result in an interruption when it is switched into service, whether manually or automatically. Such generators are typically placed upstream of the UPS to provide cover for lengthy outages. Integrated systems that have UPS and standby-generator components are often referred to as emergency power systems.

Keep the money rolling in through powercuts

Keep your tills running trough power cuts. It is a nightmare to bring all your systems back in sync after loadshedding. A reliable backup power system can save you money by keeping all your point of sale scanner and tills running throughout a power failure.

So lets use as an example - 2 x cash tills and 2 x scanners or 4 x tills - same thing. This would mean 4 x 45 watts = 180 watts in total.

The formula is:
POWER (WATTS) DIVIDED BY (VOLTS x CURRENT).

This means W= Vx I etc etc. So we have 180 divided by 12V (battery) = 15 amps (current) - now we say how long do we need it to run for - 15 amps x 4hours = 60ah (amp hours). This means we need a 60 ah battery to run 4 tills (using 180watts) for 4 hours.

4 cash tills to run for 6 hours = 180 watts divided by 12V = 15 amps.
15 amps x 6 hours = 90ah.

So here we need a 90ah battery to run 4 tills for 6 hours.

Inverter Info

You have the option of a UPS/Standby Inverter or a standard Inverter.

Once turned on both work the same.

UPS/Standby Inverter – this can be connected in-line, meaning that it can be connected in such a way that when the power fails the UPS/Standby Inverter automatically kicks in without any interruption.
Standard Inverter – this is an off-line system, when the power fails you need to turn the Inverter on.



You need to make sure that the Inverter is of a very good quality with a very efficient output power. What this means is that the Inverter must actually handle the WATTS it says it can and must do it efficiently – 90% or more is what you need.
Surge Watts is also important – it must be able to handle a surge at start up as many appliances use much more WATTS to start up and then they settle down using less WATTS to run.
Filtering – this is vital for a smooth operation.
Switch over – a must for an uninterruptible switch over when the power fails.
Thermal Protection – Will shut down safely when over heated
Leakage Protection – Stops AC output when earth leakage is detected.
Overload Protection – Shuts down safely if overloaded.
Short circuit Protection – unit will shut down safely when it senses a short circuit on the output.

About Battery Chargers

The battery charger is the heart of the system and absolutely vital for the correct operation over time.
You can have a perfect Inverter and Battery, if the charger does not do the job correctly, the system must and will fail.
Firstly the battery charger must be of a true intelligent design and the manner in which it chargers is what counts.
There are very few chargers in the World that can perform 100% correctly for this kind of application.

What is absolutely necessary 100% of the time!

1. Must be suitable for deep cycle batteries, this is critical for assuring the battery can be charged back to it’s full capacity each and every time.
2. True “ IUoU” 4 stage charging with Temperature compensation to insure a proper charge and 100% safety.
3. Battery Interactive storage prevents discharge and thus insures your battery is always 100% charged and ready.
4. Long term connection technology, assures safety and peace of mind.
5. The charging system must allow for reversion from float charge maintenance mode to full current absorb mode, without this the battery will deteriate and eventually fail

NB: Accept only a tried and tested world-class charger that WILL do the job correctly each and every time.