September 23, 2019 How to stop worrying and learn to love loadshedding

How to stop worrying and learn to love loadshedding

With the load shedding hitting Zambia hard and the threat of tariff increase on the horizon, it makes sense to look for alternative means of keeping the lights on at home.  I see questions like “how much can an inverter that can run my home electricity cost and who can install it?” on social media all the time. 

But I want you to think about it from the other end: Don’t calculate your power needs based on your existing setup and then get an inverter/battery or generator with that capacity to hook into your mains when power goes. Think about it more fundamentally and ask this question instead: “How can I optimise my home electricity infrastructure to minimise the need for costly alternative power sources?”. You might be able to do more of that than you realise without sacrificing much convenience, and you will save on setup and electricity costs as a result; read on.

These tips and pieces of advice are based on getting an inverter&battery setup, not a generator. Apart from the obvious noise and smell and pollution (which are all bad), with a gen-set you loose the enormous advantage of having a 12V powerful battery in your house.

Which is really the starting point of how to rethink your house electricity needs: Don’t think of your inverter setup as a backup electricity generator for your household el needs. Think of it as a 12V power source (the battery) with a charger (the inverter)!

12V DC For The Win!

Because really, so many of the devices and gadgets and appliances you have in your house do not in fact run on 220V AC, even if that is what you plug them into. They run on 5V or 12V DC! Internally in the device. They just have power adapters that convert 220V AC to their needed DC voltage.

Go ahead, do a round in your house and count how many adapters similar to this you have plugged in:

I don’t have a big house, but before I started converting, some of the ones I had included my internet router, kitchen downlights, security cameras, and office backup hard drive. I bet you will find some too. 

Obviously, all the devices you have in your house that run on 12V from a power adapter can be run on 12V directly from your inverter battery, which is much more power-efficient too! Without going into the calculations, looking at the input and output specs on the power adapter in the picture above, it looks like there is a power loss of approx 50% or more between input and output. No wonder it was hot to the touch.

Most of these will have standard round plugs, so simply get the 12V from the battery in a wire to the device in question and terminate that in the same round plug that the device needs.

You might think at this point, well, there is power loss in the inverter charging the battery too. Yes, but don’t loose sight of what we are doing here: We are rethinking your house electricity based on using an inverter & battery, that’s a given. The difference is that you can either use your inverter as is, and take the 220V AC output from it to power your house. Or you can follow my advice and take the 12V from the battery and use that to power a lot of stuff in your house. Do the former and you get double power loss: first convert the 12V DC from your battery to 220V AC from the inverter, then convert that AC again to 12V DC in your devices with the kind of power adapter as in the picture above. That is truly a waste of power!

5V is cool too

Now on to all the devices and gadgets you have that run on, or is charged by, 5V. Either USB or otherwise. Your phone, your reading lamp, your gizmos and do-dads. There is good news for them too:

From this…

… to this!

Pictured above to the right is a voltage converter that will take 12V input from your battery and serve it up to you as 5V in 2x USB sockets. The converter is small, fully encapsulated, waterproof, and highly power efficient. And costs less than $5 online. You can afford a few.

Tying it together

All good, but how to you get the 12V DC to the places in your house where it is needed? Well, I never said this was free. If you’re now a bit geared up about this, it’s time to tell you that I want you to rewire the el in your house. Not to replace the 220V AC wiring, leave it be for when you have ZESCO. No, I want you to stretch a network of wiring carrying 12V, fanning out from your inverter battery/batteries, to the rooms and places in your house where you need the 12V as discussed above.

And to get you to really consider this, let us talk about the lights in your house. Have a guess as to where I am going:

Yes, that’s right, you do not need to power your lights with the 220V AC from your inverter at all. Since you are already stretching wires from your battery, stretch them to new 12V DC light sockets as well, next to the old ones. Then the same net that powers your 12V and 5V gadgets can also power your lights. I am already using these bulbs and can tell you they perform very well, just as well as the normal 220V led bulbs you can buy.

And we haven’t even mentioned another big advantage of taking and using the 12V from the battery as much as possible: the AC 220V wattage output by your inverter can now be put to use where you actually need it, where there is no other alternative. Without sharing it with your lights and other devices. Which means you can get a lower watt inverter than orherwise. Which is cheaper.

I realise that not everybody has the time or inclination to tinker with this as I do. But you don’t need to. All you need is to get the stuff (see end of post) and give the right instructions to the inverter installation crew or electrician: that you want a 12V el net, which devices they should find and connect 12V plugs for, where you want the USB 5V sockets, where you want lights etc. They will take care of the wiring. And they should really tell you this, but just in case: don’t forget you need a fuse box (like one taken from a car) as well.

Other considerations

My goal for myself was really to as much as possible eliminate the “Arrrrgh” of loadshedding while at the same time optimise the cost and performance of alternative power in my house. To that end, I have a few more obervations.

I am sure not all of your devices and appliances fall in to the 5 or 12V categories. For instance, I have a mirror light in the bathroom that I discovered has a semi-internal power converter from 220V AC to 36V DC. There are solutions for this too of course, and I plan to hook it up to the 12V net using this:

In other cases, you might want to consider getting alternatives for your appliances that run on 12V instead of 220V. There is an existing big market for “stuff for use in cars”, for example, like cooler boxes that run on 12V, or, for a coffee junkie like me, a kettle, so I can get my morning coffee fix, loadshedding or not.

Combination car “cigarette lighter” 12V socket and double USB port converter….

… allows me to get my damn coffee, whatever ZESCO thinks. I concede that the kettle can boil water for tea as well

I want my MTV

I know I haven’t addressed some of the big power-hogs in your house with this: TV, Fridge, AC etc. But that’s ok. This is no magic bullet after all, it’s just a starting point for a way to think about your house el to make load shedding easier to cope with, without breaking the bank and at the same time lowering your el use and cost, and mantaining a level of comfort.

If I were to hook one more thing up to the AC output of my inverter, it would certainly be the fridge. But I have a very, very modest setup, a 300W inverter (A Fortuner UPS bought from Radian to be precise, approx K1200) connected to one 75Ah battery (approx K1000, also from Radian), and I doubt it would be able to run my fridge for very long, or at all. Apart from that, with the optimisations I have done, I am amazed about how well it is performing. The battery is now over 1 1/2 years old, and it powers living room, kitchen and office lights, router, my media/backup Mac Mini server, x number of security cameras and other security sensors ++, and it has no problems doing that for 10 hours of loadshedding straight.

Do I now love loadshedding? No, but it must mean I have done some stuff right.

Resources

12V light bulbs: https://www.ebay.com/itm/E27-Energy-Saving-LED-Bulbs-Lamp-Home-Camp-Solar-Hunting-Emergency-Light-DC-12V/231553734419

The bulbs I got were of the 7W variant. They are ever so slightly less bright than the normal 220V bulbs, so I would order the 9W variant if i were to get some more.

12V to 5V double USB sockets converter: https://www.ebay.com/itm/12V-to-5V-Dual-USB-Power-Adapter-Converter-Cable-Connector-Car-Charger-For-Phone/172597233099

12V “cigarette lighter” socket with double USB sockets: https://www.ebay.com/itm/Auxiliary-Dual-USB-Power-Outlet-12V-Car-DC-Cigarette-Lighter-Socket-Plug-Adapter/122770805590

12V kettle: https://www.ebay.com/itm/12V-24V-1L-Electric-Car-Travel-Boiling-Kettle-Stainless-Coffee-Tea-Water-Heater/123895970840

This kettle is 150W. Your normal kettle is probably 1600-2200W, so don’t expect your water to boil in a couple of minutes – patience required.

How to estimate your power needs, rough and quick (leave this to the electrician if you like, just specify exactly what you want to hook up to the battery):

Watt (W) is in this context ampere (A) times voltage (V). So the bulb shown in this article, which is 7W running on 12V, draws 7/12 ampere, approx o.6A. And the 12 to 5 voltage converters shown, you can see that they are rated 5V 3A output, meaning they output 5×3 = 15W. Which means, with neglible power loss (really), that they use 15W too. Since the input is 12V, that means they draw approx 15/12 = 1.25A.
My battery is 75AH, ampere hours. Which means that it can, in theory, when new, deliver 75A for 1 hour, half of that, 37.5A for double the time, 2 hours, and so on, 1A for 75 hours etc. Think of the AH rating of your battery as the power storage capacity. So we have one bulb that draws 0.6A and one 12 to 5V converter that draws a max of 1.25A, lets say 2A total to make it easier. So in theory, if I only hook those two things up to the battery, it can power those with constant maximum load for 75AH/2A = 37.5 hours. If your total max load is 10A, you can have battery power for 75/10 = 7.5 hours, and so on. Real world times will be lower/shorter, depending on the load you put on the 220V AC side of the inverter and the age of the battery etc.

Why I (probably) can’t run my fridge on my inverter: My inverter has an output rating of 300W. Which means, since it outputs 220V, that its max output current is 300/220 = 1.36A. My fridge has some confusing watt specifications, but it is rated as 1.5A input current. Which should mean that max watt it uses is 220V x 1.5A = 330W. Which is just above what my inverter is rated for. And I already use the AC output of the inverter to power my media center. So in this case it is not the battery that is too small, it is the inverter. An inverter rated 500W would probably have managed. Of course, if I draw 300W from the battery, that is 300W/12V = 25A which means that my 75AH battery will be empty in 3 hours (less in real world).

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