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pilotfish

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Everything posted by pilotfish

  1. Nope, the battery is a commercial unit with bms, inside a steel box with cells firmly secured, with a circuit breaker that is turned off so that the terminals on the front are dead - off course if you dragged it from JHB to Durbs behind your vehicle then there might be some problems.
  2. ...and apologies for the spelling mistake in the title
  3. Hi all Durbanites, I have a client in JHB who is moving to Durban in the new year. I recently (before lockdown) installed an Axpert VP5 and Narada 48v 100Ah LiFePO4 battery as grid backup (no PV), last week I stripped the equipment out as he will be taking it with him down to Durb's. He has asked me if I can recommend anyone in Durban to re-install, which I cant so I am asking you! Anyone that has had a happy experience with a grid backup installation - preferably involving Axpert inverter - please send me a PM with the installer details that I can pass on to my client. Thanks for taking the time.
  4. I think it is time for you to do that again and let us know!
  5. MPPT#1 will be a WRND 48v/30amp and MPPT#2 will be a WRND 12v/40amp. I have used a couple of WRND units in the field for charge only applications (no inverter requirements) and have had no comeback issues - I was able to order with conformal coating and adjust voltages to suit my lithium charge profile which swayed my decision to go with these units (and they are pretty cost effective which didnt hurt either).
  6. To simplify the above - ask your supplier what your 95% SOC voltage is (or check your battery literature), set bulk and float both to this voltage.
  7. Try lowering your bulk and float voltages on the batteries (speak to your supplier!). So what is probably happening is the following; Your float bulk/float voltage is at max, triggering the BMS to block any further charge current, You have a high inverter load being carried by the PV panels, The load then drops (eg kettle shuts off), The MPPT takes a moment to respond to the lower load requirement and would normally dump this excess power into the battery bank - but cant P=VI, so with nowhere to send the amps, the voltage must climb Your inverter senses this dangerously high voltage and so shuts down rather than blowing up Then restarts because it is set to do so. If you lower Bulk to about 52V and float to about 51.5V (speak to your supplier!!) you will find that your batteries are still reaching 100% SOC, but are still able to accept the momentary excess power referred to above. Disclaimer - The above works with the batteries I use which is NOT the same as the batteries that you are using - so speak to your supplier!!!
  8. ...not without reason tho. The 48v is for the 48v windlass and water-maker, and because it makes a great main battery, The 72v alternator is needed to be able to charge the 48v main battery, The 12v is because all critical systems nav/comm/bilge/etc run on 12v and would cost R100'sK to change, The 24v starter battery is because grunt needed to start the 120hp Perkins, The 220v is for RSA/Europe shore power and charging when available, The 110v is for USA shore power and charging when available. As for "Radio Shack", there is VHF for short range comms, HF/SSB for long range comms and weather, AIS, GPS, Epirb, Radar, Sonar, FM radio and not to forget Wifi - so fair comment I guess
  9. I like to keep my options open You left out 220v from MPPT/Inverter #1, and 110v from MPPT/Inverter #2!!!
  10. Hi All, long time since I have been active on the forum So I have a question for the more electronically enabled minds out there - I need to upgrade the power on a decades old yacht that will be cruising oceans without regular access to shore power. Referring to the attached line diagram you will see that there is 1.15kWp of solar which will charge a 48v 4.8kWh Lithium bank via MPPT (there are 2 heavy loads - a windlass to raise/lower the anchor (1.2kW) and an RO water-maker (1.2kW) - these will both be 48v in order to limit high currents otherwise required). There is also a 72v 60amp alternator which will be connected to the MPPT PV input via a C/O disconnecting PV when the motor is running. Question 1 - any concerns having a 72v automotive alternator as PV input to an MPPT charge controller? Additionally there will be a 12v 2.4kWh lithium bank that is to be charged via a 2nd MPPT with the 48v bank as input source. The 12v bank is for critical loads (navigation, communication, bilge pumps etc), so it will be quite convenient to have the 48v bank as primary source keeping the 12v bank fully topped until the 48v bank fails - the 12v bank therefore acting as a "reserve tank". I see no problem using a the 48v bank as power source for the 2nd MPPT unless anyone is able to advise otherwise. To further complicate matters there is a 24v engine-start bank which can no longer be charged by the engine alternator as this is now 72v! so I would like to charge this bank using another charge controller with the 48v bank as source (only active when ignition switch is on). Question 2 - any issues with connecting the PV input of 2 separate MPPT to a single battery bank. If yes would a PWM charge controller for the 24v bank be an option? Early draft of Line Diagram attached - thanks for looking Bella Luna Power.pdf
  11. Because you are feeding the inverter from an E/L circuit in your grid DB, and you have connected N-E on the outputs which is an earth fault. I hope the attached sketch is legible, my CAD skills are a touch lacking (I can do it but it will take the whole day!)
  12. Take a look at Annex P.4 starting on page 361 of SANS 10412-1:2017 ed2 I sadly cant share this with you because my scanner has recently croaked and I haven't got around to sorting it out, but in summary you should bond your main E terminal (from earth bar in Main DB) to your inverter N terminal (at the inverter) which will prevent your floating voltage situation. The earth conductor should be a minimum of 50% size of the Live conductors. This should be done before the inverter output Earth Leakage which I am sure you have installed. So as an example if you run a 50amp 10mm L/N from the Main DB to your Inverter L/N(in), then you should run at least 6mm from your main E-bar to the inverter body and to the N(out) terminal (looped, not 2 separate wires).
  13. I think something like the following is happening; the PV system is supplying loads and charging batteries, then a high AC load exceeds the inverter happy place causing the system to switch to grid (until the load drops again), the system then dumps the momentary excess PV capacity into the batteries, causing the battery voltage to spike while the MPPT adjusts to the lower requirement. I wouldn't be too concerned until you see smoke.
  14. Replace and carry on - fuses will often blow at lower than rated currents as a result of heat build up from other sources. Make sure your terminals are tight, wire not too thin or annealed, fuse terminal gripping tightly.
  15. That would be the best way forward if in the budget.
  16. Lots of Axpert uses have installed 3.6kWp without any issues, the main concern is not exceeding the max MPPT input voltage. If you currently have 10x300Wp panels wired 2S5P then you can increase to 12x300Wp wired 2S6P, the MPPT will not accept input above 3kW.
  17. [Joburg] In order to access the piddly feed in tariff of 42.79c/kWh you will need to jump through various hoops of diminishing diameter in order to register as SSEG, and then you will be forced to migrate to Time Of Use metering - with very high monthly fixed cost of R400-R500/m before any power consumed, and very high power costs when you need it and low power costs when you dont need it. It is just not worth it, which is by design by City Power because they dont want high earners (reliable payers) installing PV systems, they need the money for cross subsidies. COJ Tariff - TOU.pdf Embedded Generation Tariff.pdf
  18. pilotfish

    DC FUSES

    Yes I think the "short burst" capacity normally refers to the AC throughput - I know that my inverters immediately switch to grid if I exceed 4kW on battery. If you want to go the 3 fuse route I would make them all 125amp - having said that I would love someone to explain the logic of fusing individual strings in co-located parallel strings. I would use the shortest possible cable of the same length from each string to a single fuse or DC Breaker. If the strings are far apart then sure, fuse each string, but rather don't locate them far apart if it can be avoided.
  19. 1. What is your max AC demand (A) on your inverter circuit. - 36 amps/2 (18 amps per inverter) 2. What is the max AC demand (A) at your grid connection. - seldom exceeds 50 amps (in Winter) 3. What is the max DC demand from the batterys - never exceeds 166amps (4kW per inverter) 4. What is the max charging current you allow from each inverter. - 40amps each (80a total) 5. What is your total amps on your PV side. - 40amps per inverter (midday spring) 6. If you feed back to grid, What is the max (A or Watts) you export. - I don't October kWh - total consumption 909 / Grid consumption 143 / PV production 882
  20. That would be an acceptable alternative to connecting to your main earth, and if someone proposed this I wouldnt be so vehemently apposed to it - but banging in a 1.2m rod from the local electrical supplier is about as effective as nailing a 2" square piece of silver paper to the wall.
  21. So the problem is that the inverter will auto-sense 50/60Hz - when you connect the gennie with no initial load the inverter senses 60Hz input, then when it starts to draw a load it sees input dropping to 50Hz which it feels is a problem and so stops accepting power, then the gennie returns to 60Hz because the load has dropped so the inverter accepts input again .... Connecting an initial load drops the gennie to 50Hz, the inverter accepts this and start accepting input power - your gennie AVR now can maintain 50Hz so it continues to accept input until the gennie CB trips. You may need to get an inverter type gennie that maintains 50Hz electronically, or a bigger gennie with a flywheel that can carry the load variations without frequency fluctuations.
  22. I think on APL setting it will accept up to 280V, but 60Hz is a real problem unless you are a Yank (in which case 253V is even worse!) You may need a better quality gennie with a good AVR which will maintain 50Hz unless the supplier can sort that out.
  23. Note that the above applies to a stand-alone earth spike - if you want to surround your home with earth spikes that are all connected back to your main earth terminal then that is all good.
  24. So here is my opinion... The short version is >> Connect all earth terminals of EVERYTHING that has an earth terminal or requires earthing to your main municipal earth, using an earth wire of at least 1/2 the size of the main conductor, or 4mm for things that you are not sure of (TV antenna, sat dish, PV panels etc). After that do nothing because it is now earthed. The long version >> You have to be very sure of what you are doing to create a high quality earth using earth spikes. If you create a lousy earth, which you are almost certain to do, then you are creating more problems than you are curing. Your municipal earth is probably 1ohm or less - it can be measured with an Earth Loop Impedance tester which is an expensive piece of kit, so either borrow one from a friendly electrician or pay your electrician to test it. It must allow double the amps of your main switch to flow in the event of a short circuit - so for a 60amp MCB it must allow more than 120amps to flow which would require an earth resistance of better than 2ohms in a 230V supply system. I tried the spike route once at Cedar Lakes Estate where about a 200m long earth wire had been damaged in numerous places. Rather than digging up the entire estate I decided to go the earth spike route at the remote DB. The first spike gave me about 50ohms, the 2nd one dropped it to about 45ohms - five interconnected earth spikes later I was at about 35ohms - I guess about 100 spikes would have done it but by then I had decided that digging up the estate was looking like quite a good idea after all. The problem with a poor earth connection is that it cant dissipate lighting currents which will cause earth voltage in the vicinity to rise massively - now you have a 300 kilovolts in the vicinity of your one lousy earth spike and 0 volts on all your correctly bonded equipment, and a lot of stuff converted to smoke in-between (I hope that you are not one of them).
  25. I think that the MUST inverter is an Axpert knockoff and not a rebrand, so the menu's and settings are not the same. See if you have an Appliance/UPS option, if you do then set it to appliance which is more tolerant of voltage fluctuations.
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