Loadshedding solutions

[ChrisF]

The question keeps popping up: "What will it take to run my IDT during loadshedding?"

Going off grid may well be the ultimate solution.  Be it for money or rental property or any other reason, going off grid is not possible for most people.

 

This does not mean we are doomed to candles during loadshedding.

 

Every second store now sells a "battery box with an inverter" .... but what do "you" need ?  Now if ever there was an open ended question !!

 

When looking at "battery boxes" (or even the much larger systems), you need a basic understanding of some of the terms that should appear on the technical specifications.  Some of these are :

 

1. Sine wave inverter

2. VA and/or Watt rating of the inverter

3. A.h of the batteries

4. Battery type

5. Recharge rate of the system

 

1. Sine wave - when we are lucky enough to get power from eskom it is in the form of a "pure sine wave".  This is important for your appliances that use motors, i.e fridges, washing machines, etc.  Inverters use "switching" to emulate the sine wave form.  Cheaper units have a very crude wave !!  Some even include fine print that it is not suitable for use with Apple devices, due to the poor wave quality.  A friend has one of these, and has a buzzing sound on his radio, and as the load varies, so the buzz changes.  So try to get at least a "modified sine wave", ideally a "pure sine wave" inverter.

 

2. The energy use of devices is rated in "Watts".  For the purpose of this it may be considered that Watt = Volts x Amps.  That is not strictly true, as motorised devices have a "power factor" which complicates this beyond the scope of this post.  Suffice to say: "Use the WATT rating if available".  As most battery box units are used for the tv, wifi, etc the VA and Watt ratings are close enough.

 

The important bits to note with the VA or Watt ratings:

- The inverter may trip out if your total loads exceed its rating.

- A typical 12V battery uses about 8A for every 100W.  As a rule of thumb, the basic deep cycle battery which is found in most entry level battery boxes, should not exceed a 20A draw constantly during a loadshed.  (this is more about good practice and protecting the battery, and yes, many do exceed this)

PS - the correct approach is to look at the "C" value of the battery, as this dictates the correct maximum continuous current for that battery

- If your expected constant loads are going to exceed 200W, best to go for a 24V battery box unit.

 

3. The Ah rating of the battery is typically in the order of 100A.h, per battery.  On its own, this sadly means very little ....

 

4. Battery type:

- Lead acid / deep cycle : campers have use these for years with good results.  And it can do the job for a battery box ... with TWO limitations -

a) using more than 50% of the battery capacity, i.e. 50A, shortens the life span of the battery significantly.  So you need to plan, and size your system to use 35 to 45% during a 3 hour loadshed, to get the best life out of the battery.

b) charge current - typically these batteries should not be charged at more than 10A, thus a very long recharge time.  And THIS is its main downfall, as the system cant recharge between multiple loadsheds, and next cycle the battery goes below 50% ....

 

- GEL batteries : In theory is tolerates discharges down to 70%.  More importantly, it can safely handle a 15A charge current.  Thus these batteries are back to 95% before the next loadshed.  In practice .... repeated deep discharges still damage these batteries.  I use one of these, but I dont take it below 50%, and after almost 4 years it is still working very well.

 

- Lithium batteries : By all accounts this is the future.  It can handle much deeper discharges, it can charge faster, it can deliver higher currents .... and it is damned expensive ....  You will find this in the top range products.

 

5. Recharge time - as noted above, this is a function of the battery type.  In a home office a very fast recharge is an absolute must !!  For the teacher that needs back-up power for one loadshed at night, the system has all of tomorrow to recharge.  So just take note of what you need, and pay the premium if a fast charge is crucial for you.

 

 

Okay, enough basics to get the conversation started .....

[ChrisF]

The question remains: "What do you need to run your IDT during a loadshed?"

 

I have the following IDT setup:

- KickrCore

- NUC PC, running Zwift

- 32" screen

- desk top fan

 

 

Test ONE :

- KickrCore

- NUC PC, running Zwift

- 32" screen

 

I was surprised that this system only draws 70W  (excluding the wifi).  That is barely 5,4A, at 13V.

 

Thats less than 15A from the possible 50A during a loadshed.

 

 

Test TWO :

Now I added the desk top fan .... 121W total draw.

 

 

This is getting close to 10A draw, or 25A during a 2,5 hour loadshed - if you can survive on Zwift that long.  Still perfectly fine on a basic 12V single battery inverter trolley.

Edited July 14, 2022 by ChrisF

[ChrisF]

And mommy sees the battery box ... and the question is asked if it can run the tv .....

 

Test THREE :

- TV (Samsung smart tv, about 50'')

- wifi

- dstv

- media box

 

7A draw, or 90W.  Perfect for a 30 to 40% draw on a single battery during a normal loadshed.

 

The only issue being the recharge time .... for which the GEL battery works perfectly.

 

 

Welcome to the slippery slope .....

 

Next you will want to watch something on tv while on the IDT ..... PLEASE DONT take that battery below its rated charge level (for the type of battery that you bought) !!!  This is guaranteed expensive school fees !!!!!!

 

 

Set your goals .... add the Watts, divide by 12,5 to find your average Amps .... multiply by 2,5 or 3 .... check your battery capacity ..... 

 

 

and KNOW once the system works, more stuff will be connected to it ....

Edited July 14, 2022 by ChrisF

[W Smith]

Too complicated. 

 

[ChrisF]

1 hour ago, W Smith said:

Too complicated. 

 

 

more peechas, less words ...

[milky4130]

I'm with Will Smith, too complicated, can you please add some costing into the setup. My fibre & wifi is already on a cheap R800 ups from takealot. I need power for my IDT, Tv & Apple TV box, cost & which day suits you to come do the installation 😛

[Mountain Bru]

Anyone tried one of these:

https://www.takealot.com/ecoflow-river-pro-720wh-portable-power-station-black/PLID73199269

Seems like a pretty good solution for an IDT and fan during load shedding (although I haven't checked the capacities), and has the advantage of being able to be taken camping and run your fridge and lights and stuff, and can charge directly from a solar panel or car charger. 

(If it seems pricey, consider the costs of a car dual battery system - battery, inverter, solenoid/DC-DC converter, solar charge controller, battery charger,  all the little bits and pieces like a housing, usb ports, volt displays etc. And then you have a system thats wired to your car and you can't carry around)

[Mountain Bru]

Also, those rechargeable LED light bulbs are absolute game changers. (https://www.takealot.com/eurolux-battery-globe-light-es/PLID46854849)

Between having a few of those, a gas stove, UPS for the modem, and a laptop with like 8 hours battery life, I barely notice when the powers off for 2 hours. 

[cadenceblur]

1 hour ago, milky4130 said:

I'm with Will Smith, too complicated, can you please add some costing into the setup. My fibre & wifi is already on a cheap R800 ups from takealot. I need power for my IDT, Tv & Apple TV box, cost & which day suits you to come do the installation 😛

This would be my requirement as well + a fan

[Mtree]

6 minutes ago, cadenceblur said:

This would be my requirement as well + a fan

If you are slightly electrically inclined and have done some basic wiring, an inverter isn't really too much more difficult.
Only thing is the extra(pass through) earthing point etc...
Just saying it is possible to do...

**DISCLAIMER, DON'T TRY THIS AT HOME, RATHER GET AN ELECTRICIAN**

Edited July 14, 2022 by Mtree
change

[PhilipV]

11 hours ago, ChrisF said:

and KNOW once the system works, more stuff will be connected to it ....

And there's the rub. 

So suddenly what started out as shopping for a 2.4KvA ish system became a 5KvA inverter with 5KWlithium batteries and a rewire of the DB board so that life can mostly go on without noticing loadshedding. 

 

Scope creep is 'n bliksem. 

[Mongoose!]

9 hours ago, W Smith said:

Too complicated. 

 

Skeinat standaard graad?😜

[tinmug]

Edit:

It's going to get a LOT wore before it gets better (if it does get better). Plan for the mid-to-long term and start chipping away at being at least somewhat independent from Eskom.

Something like a powerwall (container with reasonable size inverter and decent battery/ies, preferably wired to solar panels) can be a practical option for those who rent.

Edited July 15, 2022 by tinmug

[PhilipV]

7 hours ago, Mountain Bru said:

Anyone tried one of these:

https://www.takealot.com/ecoflow-river-pro-720wh-portable-power-station-black/PLID73199269

 

(If it seems pricey, consider the costs of a car dual battery system - battery, inverter, solenoid/DC-DC converter, solar charge controller, battery charger,  all the little bits and pieces like a housing, usb ports, volt displays etc. And then you have a system thats wired to your car and you can't carry around)

A car dual battery system can probably be built cheaper by yourself. And building it into a portable battery box is easy. I've done it before.

But it won't be as slick and we'll presented as this solution. 

[PhilipV]

10 hours ago, W Smith said:

Too complicated. 

 

That's how I feel about taxes. 

So ask someone who understand it to build/spec a system for you.

Fortunately I married an Accountant. I handle the watts and amps and cars and stuff, she crunches the numbers. 

 

[117]

8 hours ago, Mountain Bru said:

Anyone tried one of these:

https://www.takealot.com/ecoflow-river-pro-720wh-portable-power-station-black/PLID73199269
 

I have a simillar unit, called a Jackery. It's a great little unit but they have their limitations. I'd be keen to see if it can run an IDT though (I don't have an IDT but I'll get a pal to test it on his) 

The jackery can run the telly/router and a lamp for just under 3 hours as an example, and back to full recharge via eksdom or car in under 6 hours

Also busy installing a 5kva Mercer inverter, that'll drive the whole place for a day