Jump to content

Richard Mackay

Members
  • Content Count

    681
  • Joined

  • Last visited

  • Days Won

    2

Reputation Activity

  1. Thanks
    Richard Mackay reacted to Kalahari Meerkat in BATTERY BACKUP TIMES   
    This link as already provided in my 1st post above...
  2. Thanks
    Richard Mackay reacted to Luminous in Conversion of circuit breaker mounting   
    I feel they could have spend a bit more time on those adopters or make a better one. Those are flimsy and after the second time you try to fit it nicely it is worn out.
  3. Like
    Richard Mackay got a reaction from Pumba in Conversion of circuit breaker mounting   
    Rather build another DB with DIN equipment. Mixing the two is never going to be satisfactory.
  4. Like
    Richard Mackay got a reaction from Erastus in COCT Generation of set Insentive makes batteries to expensive !!! Well done COCT   
    IMHO stands for "in my humble opinion"
  5. Thanks
    Richard Mackay reacted to Kalahari Meerkat in Home UPS Questions   
    Powering from DC I'd recommend the following:150+66
    Avoid lead acid, else you will have to come up with a "BMS" for these to ensure you only draw a certain %age out of the battery, lets say 20% and have a decent charging circuit that won't get the battery into gassing territory on re-charge to enable a reasonable life out of these
    I recommend a LiFePO4 pack per application with BMS and charging circuit for the the battery pack, again limited discharge and ideally also charge, if you can calculate your need per consumer item/battery pack and keep the charge to 90% max and on the bottom end above 20%, you can likely expect 10+ years out of the battery pack assuming, of course your current draw is less than 1C, which is most likely to be, I'd imagine more like .2C or so, which again is a recipe for a longer life for these
    Now since you're running 12V devices, maybe best would be to gather them all together (proximity to each other to keep cabling doable?) and run one LARGER 12V LiFePO4 battery with BMS and charger that can talk to BMS and keep things within certain limits >20% <80% and for the 19/20V laptop, you can probably run a DC to DC boost converter that takes the 12V and gives you 20V, I do this for an old Dell Laptop, where the original charger let out the magic smoke a few years ago and the battery pack, by now, is toast as well.
    You'd need to calculate, for the DC devices, what running time/period you'd expect and do the sums to come up with the capacity batter(y/ies) required.
    As an example: 100+42+12+12+150+66 as thumbsuck figures you've provided = 382W if my mental arithmetic doesn't fail me. So, let's call it 400W per hour and this is 60% of battery capacity to ensure a long life, so if you're catering for 3 hours, that would be 1k2W which is 60% of 2kW's worth of battery capacity, or around 180Ah capacity.
    Now, this is overkill, since the laptop doesn't consume the 150W app. you specified, my Apple 15" retina MacBook Pro, sits here at less than 30W mostly, unless I'm compiling something etc. it isn't consuming the power that its 95W DC power supply would indicate, it has a 256GB SSD, 8GB RAM and a 3d gen i7 mobile CPU, but also I'm using an external display and not the built in display. The external display probably consumes, maybe 40W, I'm not sure.
    Basically you should probably do some power measurements over a few days or so on every DC item you would look at putting on DC backup power to get a more realistic idea of what they consume, a WiFi AP may have a 1A 12V rated PSU, but probably consumes somewhat less than this specified power, let's see WiFi RF is limited to 500mW max, let's say dual band, that's 1W RF for 2W DC in, CPU etc. maybe 5W for the AP, I'd think, but better to measure, the point though, if you use the specs of the PSUs, then you will be catering for more consumption than you actually need and if lack of funds is a criteria, then more homework is needed.
    * any and all typos and speeling mistakes are mine, tough, don't have the time to proofread and fix right now ūüôā
  6. Like
    Richard Mackay reacted to PeterP in COCT Generation of set Insentive makes batteries to expensive !!! Well done COCT   
    You are currently making good return and your system will have a very high IRR, but it seems you are exporting more than what the CoCT SSEG system allows for (ie you are not currently a net consumer). Net consumer is calculated on annual consumption and production so you might still be ok once winter is taken into consideration, but seeing your impressive tracker results, I'm not sure
    You are missing my point about having the option to add batteries, of course it will be more expensive and thus IRR will be potentially reduced but batteries are all about having power when Eskom can't supply - for most people (not you), eliminating loadshedding, is as important as the ROI. On a small residential system the Hybrid inverter may add R10K up-front, but then you are at least able to add batteries at a later point if the feed-in tariff is reduced (or eliminated) - or loadshedding ramps up even more.
    One of the main problems with CoCT SSEG feed-in system is that you are effectively entering into a 1 year contract with the City on your 20-25 year solar investment. The monthly SSEG connection fee, tariff and feed-in tariff are changed annually which means your system IRR is very vulnerable, especially if it is dependent on the feed-in, to achieve savings (eg. City may only offer R0.33/kWh feed-in next year or R0.10/kWh or none at all.....). The R0.25/kWh incentive is for first year only and may not even apply to systems added in future years. If CoCT would offer a feed-in deal fixed for 5 years then we'd be able to do our sums and make much more informed decisions.
    With a self-consumption battery system you will fix your R/kWh rate for life of system (currently R1 - R1.50/kWh) so it's a bit easier to work out the IRR as the Eskom kWh tariff historically has only ever gone up. Feed-in tariffs world-wide have mostly been coming down.
    Currently, hybrid battery system in Cape Town expected pay-back is 5-8 years, grid-tie SSEG can be as low as 3-4 years (but no grid - no worky).
  7. Thanks
    Richard Mackay reacted to OceanWanderer in Home UPS Questions   
    Resposting

  8. Sad
    Richard Mackay reacted to GordonT in Conversion of circuit breaker mounting   
    Thank you ... Building a new Db board  without a major renovation is just not possible. I would like to do that but with a prepaid meter and getting council involved That becomes a hold new can of worms... Thanks Anyway GordonT
  9. Like
    Richard Mackay reacted to GordonT in Conversion of circuit breaker mounting   
    Good Morning all......  Your help required
     
    Is it possible to convert Circuit breaker mounting from standard to din
    Many  Thanks 
    GordonT
  10. Thanks
    Richard Mackay reacted to Calvin in Reducing power consumption and energy wastage   
    The physics is easy: the specific heat of water is about 4.2 kJ/kg.  This means that 4.2 kW will heat 1 kg of water by 1C in 1 second.
    More practically a 3kW element will heat a 150l geyser by 1 degree in 210 seconds, or about 17C in an hour.
    These numbers do of course exclude heat required to warm up the geyser itself, as well as heat losses occurring during the heating. but they are relatively small.
     
  11. Like
    Richard Mackay reacted to TonyH in My New project   
    I haven't installed yet. I am about to start ordering. QF5 is a rotary switch that switches both live and neutrals. The CT is directly from the Grid feed. I have modified my drawing attached

  12. Like
    Richard Mackay reacted to Brani in Oh No!   
    Methinks load shedding has nothing to do with coal supply or any other nonsense they are trying to feed us.
    NERSA negotiations are at the critical stage.
    Another worrying fact is that they are shutting down during the weekend, where the demand should be lower. I am scared to mention that 19,583MW is down (close to 50% of capacity) and think they simply don't want to run diesel generators as it costs a fortune.
    Eskom's 46665 employees average salary of R785557 per year and debt of R488 billion equates to over 10 million debt per employee. As an analogy, if you are an average employee and stood there and did nothing (not cause damage), you could do that for 13 years before this debt is accumulated.
    Of course there are many capable workers at Eskom, but the rot at the top is unbearable. The country needs to break it down as soon as possible, if we want to save the economy.
     
     
  13. Thanks
    Richard Mackay got a reaction from Tsa in Relays, Contactors and more   
    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!)
  14. Like
    Richard Mackay got a reaction from Speedster in 3 Year Old New-in-Box Agisson TCB-400A 2V 400Ah Batteries   
    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!
  15. Like
    Richard Mackay reacted to Kilowatt Power in 3 Year Old New-in-Box Agisson TCB-400A 2V 400Ah Batteries   
    They are up for auction - "as is, where is" basis. Shall not bid above current scrap battery prices i.e. US$ 0.50/kg
  16. Like
    Richard Mackay got a reaction from Energy-Jason in Financing Solar With House Bond   
    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!)
  17. Like
    Richard Mackay reacted to introverter in Financing Solar With House Bond   
    manners first, all well thanks.¬†¬†you and yours?¬†ūüôā
    Fact: all the major South African banks seem to offer some sort of "alternative energy" finance option. There are also numerous smaller/independedent finance options specifically aimed at solar (I am not posting links to these or the banks ...they can generate their own traffic). You should be able to access your bond to finance shiny things on the roof (suspect solar is the new Gucci for some people..if you understand Afrikaans there is an Anton Goosen song that deals with things on a roof...and Gucci) -  especially if you are a bit ahead on the bond (been paying extra every month...) or have reduced the outstanding amount a bit.
    Opinion: Unless you MUST, don't do it for the reasons as already posted by the much more qualified members. How to test?....see how eager the bank is to finance/refinance etc. what you want.... the more eager they are the more likely you know you are to get screwed from a financial benefit perspective. It is different if you are a business/commercial enterprise that NEEDS electricity to produce income... or work from home with potential VAT and tax benefits ... but then you would likely have asked the question to the people doing all those nice income statements and depreciation calculations  etc. for the friendly people at SARS ( not the one that used to operate trains). If you need to power grandma's iron lung, maybe also worth it.....
    Advice: If you need to keep up with isidingo...or want to avoid the barefoot dance of joy, with all known and newly coined expletives as backing tune, after stepping on a lego in the dark (that also gets you called into school because the source of the stray legos repeated your gansta rap to absolutely no amusement of his grade 2 teacher)... rather buy a torch and a chess board.
  18. Like
    Richard Mackay got a reaction from YellowTapemeasure in Basic load shedding solution   
    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?? 
  19. Like
    Richard Mackay got a reaction from YellowTapemeasure in Basic load shedding solution   
    R850
    This is a locally made product.. 
  20. Like
    Richard Mackay got a reaction from YellowTapemeasure in Basic load shedding solution   
    Thanks for the info. I couldn't get onto the site...
    So 8800 mAh will be 4 cells in parallel. The nominal voltage is 3.7 V so the capacity is 33 Wh (assuming no losses with the DC-DC boost converter..)
    Have a look at this: https://pupups.co.za/  The battery is a 7Ah SLA which has a capacity of 84 Wh (and no DC-DC converter for 12V loads)
     
  21. Sad
    Richard Mackay reacted to GreenMan in Inverter not charging a UPS   
    I think the fact that it does not mention true-sine wave means that your unit is a modified sine-wave design.
    A sure way to check is to get one of your tech savvy friends with an oscilloscope to check the waveform on the output of the UPS (using a suitable step down transformer). Picture from https://www.nytimes.com/wirecutter/reviews/the-best-gear-for-your-road-trip/

  22. Confused
    Richard Mackay got a reaction from YellowTapemeasure in Helukable 6mm2   
    Only the imported cables have the info printed on them.
    Any regular locally made cable available from electrical wholesalers doesn't.
  23. Like
    Richard Mackay got a reaction from YellowTapemeasure in Helukable 6mm2   
    Identifying cable sizes can be confusing, especially when the info isn't printed on the cable!
    What I have found useful to check on cable sizes is to use bootlace ferrules to check this.
    https://online-electrical.co.za/collections/bootlace-ferrules
  24. Thanks
    Richard Mackay reacted to Achmat in Beginner Noob questions   
    Double of you are running from AGM as you don't want to run them below 50% SOC. Which takes me to 200Ah.
  25. Thanks
    Richard Mackay reacted to Solarphile in What do you miss the most during power outages?   
    While I am practically off grid now, I wasn’t always in this position. 

    Years ago I started with one 180w solar panel, a cheapie 20A pwm controller and a 105Ah deep cycle battery. All the rooms in my house were fitted with 12V 5W LED down lights that ran straight off that battery. I also had two 12V 10W LED floodlights into the back and front yards. 
     
    The¬†idea of having lights on¬†everywhere changed the whole family‚Äôs¬†mood and made the load shedding more tolerable. ūüėä
    We would have missed lights the most during load shedding. 
√ó
√ó
  • Create New...