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Richard Mackay

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Everything posted by Richard Mackay

  1. In the bad old days when you could add water to these batteries when applying an equalization charge. So the battery electrolyte could be topped up. These days with most batteries being sealed or semi sealed you can't do that. (Good for battery sales I guess!)
  2. Steer clear of inverter UPS's if you can. These devices generate 220V which often isn't required. They draw a heavy battery current even when there is no load connected.
  3. Having tried this type of UPS solution myself for a few years I became disillusioned with it. This was due to the cost of the deep cycle batteries that need to be replaced every 2 to 3 years at considerable expense. You didn't have this system long enough to experience this disappointment. I think that it's strategically better to implement a solar PV inverter instead. Sure it's going to cost more but the solution is not a temporary one. If cost is an issue one can build your system progressively starting with the inverter and batteries first and then adding PV panels later. The challenge with this however is being able to have a vision of what your total system will look like before you start.
  4. How long did you use your Ellies UPS before moving on to solar?
  5. Simple and cheap? A DC solution will be a fraction of R10k!
  6. A DC solution is a lot simpler. Your alarm system will already have a battery installed (typically a 7Ah SLA battery) If this isn't providing enough backup I suggest you replace the 7Ah battery with 18Ah. The recharging will take longer after a power outage but worry about that as and when..) As far as broadband internet backup this unit will keep your system going for the whole day (8hrs) https://pupups.co.za/ Price is R850
  7. I presume this is to survive power outages? All the items besides the fridge can be powered by low voltage DC so there is no need for an inverter. (If the fridge door isn't opened often it will maintain its temperature) A DC solution is way more efficient and costs a fraction of an inverter.
  8. Inverters can have their output floating due to the electrical isolation between the input and the output. (This is often the case with DC power supplies as well) This isn't a bad thing unless the output voltage 'floats' away from earth which can cause a high voltage to ground. I'm sure that the manufacturers won't allow this to happen..
  9. Yes the neutral is connected to an earth mat at the substation. In the US they often have the earth at the mid point between live and neutral. The earth leakage should still work even if the earth isn't bonded to the live or neutral. These devices determine the current balance between the two. If there's an inbalance it means some current is flowing to an external circuit.
  10. If we can tweak the grid voltage up a bit after power is restored to get your inverter running (and then drop it back to the actual voltage) will this get you going??
  11. There is probably a fix for this. Do you need the grid to power anything or is it only to fire up your inverter??
  12. Yesterday I did get a wallop but I think it woke me up rather than the alternative..
  13. I hope my multimeter is good enough to measure voltages accurately and that I'm capable of using it so that I won't be classified as 'fooling around'.
  14. Good question! A contactor is a large relay normally with 4 contacts and is used to switch motors, heaters or any heavy current device. To mount usually clips onto a Din rail. A relay is normally smaller and is often installed directly onto a PCB. It has fewer contacts but will have NC and NO as standard..
  15. An off grid system isn't connected to the grid.. And if the grid fails the supply doesn't become a short circuit. There will be the substation transformer winding and all the other users who are connected to that supply. Yes, the voltage drops to zero but it's not a short circuit!
  16. Hairdryers are as hectic a load as electric kettles. Murder for any battery backed up system!
  17. I'm not convinced! There has been ZERO encouragement to encourage the use of solar PV from the utilities. (In fact they look like they are actively discouraging it!) Check out this article on what some other countries have done: https://www.economist.com/technology-quarterly/2021/01/07/how-governments-spurred-the-rise-of-solar-power
  18. Grid tie inverters have been superseded by hybrids. These are more flexible with storage capacity. The idea of grid tie was that the grid served as your battery. This was a great idea but the utilities had a problem with this (which I still haven't fully fully understood) So now they have all sorts of criteria if yo want to export to the grid, so much so that it just isn't worth it!
  19. And the most significant aspect of grid tie inverters is they do not have batteries.
  20. This relay is fine. The only issue one has with connecting to existing circuits is where you install these devices. To make a neat job it would be great to keep the switchgear in the main DB and control these from another board. But looking at this relay it doesn't fit in a DB with the rail type mounting that they use.
  21. Cape Town is a bit difficult but besides AC-DC try Electromchanica: https://goo.gl/maps/tvdMiyrkmJBZBB9v7 They are the agents for Findler relays which are excellent. (My experience is they are making an effort too!)
  22. You can't go wrong by bidding the scrap value. If you can measure the terminal voltages and the voltages are ok then that's a good sign!
  23. Great topic! Being obsessed with this subject (like a few others on the forum) one does run the numbers over and over in your head.. However what I do reckon is a 'no brainer' is when you get the opportunity to get the 'solar' appliance then do so. So when the geyser bursts and the geyser, ceiling and carpets are replaced care of the insurance, don't let them install another old school geyser: get the one you were wanting to buy one day. Of course this begs the question of what system are you planning for your house. This is a tough call because we are all on a learning curve (and there will be school fees built into this for sure) As an example of my journey I started thinking that a dedicated solar PV hot water system was ideal. Then I went off that system in favour of hot water heating done by the main PV array on a scheduled basis. Now I've gone full circle back to my first choice (and have bought it as well!)
  24. We need an unbiased, honest adjudicator.. (definitely no politicians!)
  25. Maybe we should have a 'shoot out' to see if these contenders can deliver on their promises.. To make it more exciting It needs to have at least one other (reputable) contender at the same price. Agreed??
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