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Power outages


Richard Mackay

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On 2019/12/30 at 8:28 PM, Richard Mackay said:

When the lights go out what do you miss the most?

For me I guess that sudden family time, kids running into my bedroom looking at me as their hero for answers, for a while I had their full attention.😃

Now these days, Forbid. I get the blame and Eskom is in the clear should the slightest dip in power happens.😬

Looks like I will never win.

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4 minutes ago, PaulinNorthcliff said:

I have been running a single Growatt 2Kw direct inverter for two years now on an independent string of panels... feeding back into a simple plug point.

It's a great setup and has given next to no hassles.

I believe that Scott at Get Off The Grid is about to be appointed as the Growatt importer.

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Ok so you dont have a lot of moola, 

1. Buy a Cadac stove or a 2 plate stove that you hook up to a 9KG cylinder - Food Sorted.

2. Buy small 12v LED strip lights and wire them into each room with a bed lamp switch in parallel

3. Buy a 12v battery 100Ah around R1k (this is the most expensive part of your startup kit) Connect your LED lights to that- Lights sorted

4. Buy a battery charger. to charge the battery when EKSDOM is on.

5.  Save and When you have moola again Buy a 3KVA 24v pure sine wave inverter Around R7k (you can get the 48v as well but then you need more batteries)

6. Save and buy 2 x Batteries  R4k (if you have the 48v inverter buy 4 batteries R8k)

7.  Buy cables and connectors and install as loadshedding kit  remember this kit will not run your house, some rewiring must be done. budget around R2-3k

8. Buy solar pannels x2 R4k and add to the system- grow your system by buyng pannels when you have money

9. Batteries will have to be replaced save for this.

10. Buy pannels of the same characteristics to add to your system. EG if the panle is 335w at 40v then get pannels that are 335W at 40V. If you mismatch pannles it effects the amount of power you van get. 

 

 

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23 hours ago, Jaco de Jongh said:

every few months to a year, when you replace the batteries for the client, they still ask, but why does the batteries not last

Yeah, there is that. That is part of the "quality concerns" I have. One can do better with the batteries, and I don't mean LFP. There are AGMs on the market that are much better for cycling. Of course they cost more money.

10 hours ago, Krokkedil said:

6. Save and buy 2 x Batteries  R4k (if you have the 48v inverter buy 4 batteries R8k)

IMHO you should aim for 200Ah batteries. Just generally a better "neighbourhood" for batteries, because the average caravaning/leisure guy does not buy in this segement (and 4x4 megaworld/outoor warehouse don't sell 'em either). And they are around 4k each.

10 hours ago, Krokkedil said:

9. Batteries will have to be replaced save for this.

That's the main cost. Even when people buy those 8k trolleys from the hardware store (just add batteries), I remind them that batteries will most likely not last 6 months...

4k buys a large amount of petrol... 🙂

 

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8 hours ago, plonkster said:

That's the main cost. Even when people buy those 8k trolleys from the hardware store (just add batteries), I remind them that batteries will most likely not last 6 months...

 

Inverters (UPSs) hammer their batteries. Large current is drawn from the batteries when they are on. Lead acid batteries only have a limited number of cycles so it's a good idea to manage your UPS manually (I.e. don't let it fire up when you don't need the facility!)

I battle to get clients to do this (even the smart ones). Part of the problem is that a UPS is designed to fire up when the power fails... :(

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On 2020/01/02 at 11:04 PM, Energy said:

We built this for a client

That's really lekker.  Is that Growatt the SPF-3000?

I have to replace my 4x100ah Guardian UPS batteries (R8k) as they have done their five year duty, and two of them are no longer chargeable (the top two in the enclosure in series interestingly or coincidentally) after stage 6 and two 8 hour outages as a result of transformer trips / repairs last month.

I've been thinking of getting something like that to supplement my grid tied solar to cover my night time usage (between 2.5 and 3 kwh) over and above load shedding, but struggling to justify the cost.

That looks around R40k of kit at retail prices before labour, shipping, commissioning etc etc. 

@plonkster would you suggest two 200ah batteries instead?  What would be the direct benefit of 4x 100ah batteries of similar quality besides saving a bit of space?

Might just start with upgrading my UPS inverter to something similar to the Growatt for now. The one I have is a 24v 2000Va/1200w SantakUPS, not dissimilar to the Ellies one I expect.  I see there are some comments above about staying away from these little inverters, but honestly this device has done exactly what it was supposed to do within the usage parameters originally specified.  But I want something 'smarter'.

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1 hour ago, IdlePhaedrus said:

would you suggest two 200ah batteries instead?  What would be the direct benefit of 4x 100ah batteries of similar quality besides saving a bit of space?

Let me clarify a bit, I mean this in the context of making a kit for someone who just wants "lights and internet", in other words, the kind of guy who doesn't really understand all the technical stuff and maths behind it. It is much better to shove a 200Ah battery into such a kit, the obvious first reason being that you can handle a bit more load (re UPSes are usually designed on the battery-hammering limit), but the other reason is that as you move above the 100Ah fray you kinda graduate into a segment of the market where the quality is a bit better. You generally have to go to a specialty place (not the local outdoor place) to even get hold of it.

So when you deal with the guy who just wants basic loads and has no idea what he really needs... I feel more comfortable steering him towards the bigger battery.

Of course he is still going to kill it eventually... and ask why... 🙂

 

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My elderly mom asked me to make her something for load shedding. She basically just want something to power the TV, Dstv, one or two led lights and something to charge her phone.

I bought a 24v Lithium battery and 3kw inverter on AliExpress. The battery came with its own charger. I fitted it all in a plastic box with a multi-plug stuck on the outside. Works like a charm.

https://www.aliexpress.com/item/32914453789.html?spm=a2g0s.9042311.0.0.27424c4dyNiuCM

https://www.aliexpress.com/item/4000123922342.html?spm=a2g0s.9042311.0.0.34934c4dfCs49F

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6 hours ago, Richard Mackay said:

so it's a good idea to manage your UPS manually

I thought this was entirely down to whether the UPS was online or off-line. 

As far as I understand it any inverter that has a "transfer time" to switch from failed utility to battery is essentially off-line and won't run the load off the battery all the time.

Apologies if I am not correct in this assumption and please correct me if I am wrong.

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1 hour ago, IdlePhaedrus said:

I thought this was entirely down to whether the UPS was online or off-line. 

As far as I understand it any inverter that has a "transfer time" to switch from failed utility to battery is essentially off-line and won't run the load off the battery all the time.

Apologies if I am not correct in this assumption and please correct me if I am wrong.

Correct! (I'm referring to UPS's here) If it's an online device then it then the mains power (when available) is rectified to a DC rail BUS and then this is used to generate the mains voltage supply by the Half-bridge DC-AC Inverter.

So the mains voltage itself never appears at the output of the unit. All that changes is where the inverter sources it's DC BUS voltage from..

image.thumb.png.571f73ad0d90502149dc3af82a8df831.png

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However for low voltage devices (which we are seeing more and more of) these AC inverters are less efficient than DC (battery) backup.

If you dispute this then do a test by powering your 12V device by an inverter producing 220V and  power adapter reducing it to 12V vs powering the device directly from a battery.

 

Edited by Richard Mackay
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On 2020/01/02 at 10:06 AM, Jaco de Jongh said:

Believe me, For a DIY project, please go ahead, but offering something like that to a client again, without a serious contract, never ever again..........

I've learned not to keep my hobby projects as hobby projects.  I remember my MythTV system 20 years ago.  Everyone would tell me I should make systems and sell them.  I was smart enough even then to know that what satisfied me would not satisfy a "it needs to just work" customer.  I hardly noticed the quirks.

I've also done VOIP for nearly as long and in that space it took some time to get the wrinkles out and to be able to deliver service that just works.  We are there now, but its always harder than you think to get tech to the "just works" stage.

 

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19 hours ago, Richard Mackay said:

If you dispute this then do a test by powering your 12V device by an inverter producing 220V and  power adapter reducing it to 12V vs powering the device directly from a battery.

I don't dispute this at all.  Any 110/220 AC source that needs to be stepped down by inverter to DC (regardless of specific voltage) will not be as efficient as feeding the device from a DC battery directly.  But an online UPS is only generally required where the device is absolutely critical, like medical devices for example, and are usually more expensive than offline UPS's.  But this is all pushing this thread off track and not overly relevant I don't think.

Feel free to poke me in the ribs by DM 🙂, but I would like to see more about what others are doing or going to do given that load-shedding is back, and is likely to be be around for a bit given that Eskom were short of 16gw of capacity on Saturday morning.

I really liked @Energy 's solution, but the cost is beyond my pocket.  If similar could be achieved for two thirds the cost then we are talking cool bananas, especially in relation to existing grid tied situations.

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4 minutes ago, IdlePhaedrus said:

I don't dispute this at all.  Any 110/220 AC source that needs to be stepped down by inverter to DC (regardless of specific voltage) will not be as efficient as feeding the device from a DC battery directly.  But an online UPS is only generally required where the device is absolutely critical, like medical devices for example, and are usually more expensive than offline UPS's.  But this is all pushing this thread off track and not overly relevant I don't think.

Feel free to poke me in the ribs by DM 🙂, but I would like to see more about what others are doing or going to do given that load-shedding is back, and is likely to be be around for a bit given that Eskom were short of 16gw of capacity on Saturday morning.

I really liked @Energy 's solution, but the cost is beyond my pocket.  If similar could be achieved for two thirds the cost then we are talking cool bananas, especially in relation to existing grid tied situations.

Hehe thank you. What cost are you wishing for?

Jay

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4 hours ago, IdlePhaedrus said:

I don't dispute this at all.  Any 110/220 AC source that needs to be stepped down by inverter to DC (regardless of specific voltage) will not be as efficient as feeding the device from a DC battery directly.  But an online UPS is only generally required where the device is absolutely critical, like medical devices for example, and are usually more expensive than offline UPS's.  But this is all pushing this thread off track and not overly relevant I don't think.

Indeed!

A new device has appeared on the market called a Mini UPS. This is essentially a DC power supply with battery backup and a charger that will provide a DC supply during power outages. They tend to be cheap with little capacity (designed similar to a power bank) using Li-Ion cells in parallel and then cranking the voltage up to 12V etc.                                 

The up side is that they are efficient and if you are trying to keep low voltage devices (routers, LED lamps etc.) running then they have a place as a permanent fixture.

 

Edited by Richard Mackay
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Another nice thing is the LED spotlights you get with its own solar panel. I bought a couple of them before my inverter installation and these just compliment my backup system. During load-shedding at night time I notice them first.

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14 hours ago, Richard Mackay said:

Mini UPS

That sounds a little like the "Solar Generators" I looked into a little while back (bit of a misnomer):

https://www.takealot.com/lithium444-power-pack-by-flexopower/PLID53187537

https://www.loot.co.za/product/goal-zero-yeti-1250-portable-generator-with-cart-220v/rcbw-5596-g510

https://www.sustainable.co.za/goal-zero-sherpa-100-solar-power-kit.html

https://solagize.co.za/product/goal-zero-yeti-3000-lithium-portable-power-station/

@Energy I did a bit of calculating yesterday and I think a more complete battery solution to compliment my grid tied setup is still too expensive per watt hour to my frugal mind.

I went to chat with Cooper Power this morning who I got my UPS from in 2014 and it kinda confirmed my suspicions regarding cost. 

So I am likely just going to replace the batteries in that for now so I can work during load shedding, and tackle a more comprehensive solution down the line when the watt hour for batteries gets a little closer to the price from the utility.

 

 

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