Tuesday, 25 March 2008

Battery+inverter or generator: the Pro's and Con's

With all the blackouts aren't you thinking of getting a Generator for your power needs? Well after reading this article you might put that "Genie" on hold for a battery/inverter combination!

This article that was sent to me by the "SA Community Information Centre" cic@constantcontact.co.za - an organisation that is dedicated to preventing crime in South Africa.

Why not visit their web site here: http://www.cicfamily.co.za and support them.

I found it very informative and decided to share it (with small modifications):

To shed light or not to shed light, that is the question?
Here is an informative e-mail we received that might help us through the dark times ahead:

With all the rumours that are currently flying around regarding the onset once again of "load shedding" I thought I would send you the following, with the hope that if you can send it out on your mailing list it might prove useful to some of your family members, and keep the neighbourhood peaceful as well as safe.

After careful consideration and talking to a number of specialists on the subject, I came to the opinion that generators have a number of disadvantages.

They are expensive to buy and run and maintain, the smallest you can reasonably expect to supply you with sufficient power is a 5kVA, a good/safe one of these will cost anything from R10,000 to R20,000.
Storing petrol is dangerous and whilst most people do it for their garden lawnmower etc. the amount needed for a generator is too much to be safe and I felt that with the maid or gardener handling it, it was an accident waiting to happen.
Generators are excessively noisy and will disturb the neighbours, they cannot be safely operated in a garage or enclosed space, and they emit dangerous exhaust fumes and must be well ventilated.
Most, if not all of them create a poor power supply with a number of "spikes" that will blow your computer and damage most household appliances. You have to make sure that your water heaters and certain other circuits are turned off before starting the generator and then you have to make sure the generator is properly switched off when the power comes back on to prevent feedback which again will damage your appliances.
If you are not at home then your wife, maid or kids will have to set it up and start it.
Taking all this into account I decided to make up my own solution.

I added up the total Wattage of what I wanted to run during "load shedding" and I purchased:
  • 1 x 1,000 Watt inverter: cost R1,250 from PSS Distributors Nr ABSA Stadium
  • 2 x 100 Amp "Deep Cycle" no maintenance batteries: cost R900 each from Dixons Batteries in North Coast Road.
  • 1 x Intelligent charger: cost R850 from Dixons Batteries or Makro.
  • Total cost: R3,900
There are two ways of using this system, the first and easiest is to simply connect it up and put an extension cord and multi plug into the inverter, connecting whatever you choose to run to this.
The second is what I have chosen to do, that is to get an electrician to disconnect the circuits I want to power from the Eskom supply (Distribution Board) and re-connect them to my unit, when the power goes out they just keep on working, when it comes back on the charger kicks in and recharges the system, basically the circuits I have selected are now running permanently from the inverter.

I have connected my outdoor security lights, alarm system, lounge sockets (T.V. DSTV and a couple of standard lamps), all my bedroom sockets for bedside lights and my office telephone and computer system). It might sound complicated but it’s basically just a bigger version of the UPS systems many of us are already using to power our computers, and the inverter is something every caravanner and camper knows all about. The advantage is that it's silent, safe and convenient, you can make it as big as you want, to power as little or as much as you need.

It’s not advisable to use it for the cooker, or for your hair-dryer, vacuum cleaner nor kettle, but then neither is a generator and with a 2 hour power cut it's surely not too hard to do without those.
You could run the refrigerator but again for two hours you don’t really need it.
You don’t need two batteries unless you are going to run a lot of items, as I do. Then it is advisable to have two batteries linked in parallel
- the electrician has calculated that I can run all I have allowed for up to 4 hours without the need to recharge the batteries.

Points to be aware of:
  • You must have "Deep Cycle" batteries, preferably low maintenance [normal car batteries are not designed for this purpose and will not last very long].
  • You must have an "intelligent" charger: it’s worth spending a little more on this to make sure it does the correct job.
  • If you have more than one battery always connect them with proper heavy duty battery connectors (you can buy them at Midas) and "in parallel" [that’s + to +, and - to - otherwise you will increase the voltage from 12 to 24 volts and damage the inverter!]
  • If you decide to make this a permanent set up (as I have) then get a registered electrician to connect it up for you. (If all you are going to do is run an extension cable and sockets from this then you can easily set it up yourself.)

The advantages are obvious:
  • It’s cheaper than a generator to both purchase and run and maintain.
  • It’s silent: a generator in every house is going to drive us all to distraction.
  • It’s safe: no petrol to store and no exhaust fumes to ventilate.
  • It’s fully automatic if you’re not at home it just kicks in and does its own thing.

Here's more info:

Stay tuned for an upcoming blog on "how to choose your generator": size (KVA or Watts) and how much can I connect to it? Plus: safety tips,


  1. Based on my recent experience, every electronic appliances has it's own pros and cons. Well Your article is pretty good and I learn a lot from your blog. Thanks for sharing your views.

  2. Your blog is nice and informative for me. Thanks for sharing your views.

  3. South Africa’s electricity infrastructure increasingly demands reliable supplies of electrical power, making on-site power generation indispensable for commercial, medical, industrial and residential users. The growing rate, inconvenience and expense of unpredictable power outages provide a significant need for generator sets to ensure that businesses keep operating and homes stay comfortable.


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