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Thank you for the great forum, Safe Driving over the weekend. Sincerely Jason

plonkster

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plonkster last won the day on July 15

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About plonkster

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  1. Indeed. My thinking is that if you have a linear load with a power factor of one (and let's assume the CT is clamped that way), then the current and voltage will be exactly in phase. If you then tell your inverter to push back, and assuming the inverter maintains a power factor of 1, I'd expect the current waveform to be exactly opposite to the voltage waveform. And if you are balancing the power to zero... well then some really weird stuff usually shows up and the current appears to be around pi/2 out of phase (as is seen here).
  2. I would expect the current waveform to be shifted pi radians (or 180 degrees for the rest of you plebeians) from the voltage, and to be a nice smooth sine wave. Man... that thing probably cost 30k+. Leave that sticker on for as long as you want as far as I'm concerned!
  3. Practically it would probably do the trick, but I'm pretty sure it has a huge NDZ (non-detection zone). I mean, assume the grid has failed and my inverter failed to disconnect, and I'm inadvertently feeding 50mA into my feeder line. That's enough to kill someone, but it's only 10W going in the wrong direction. Still, impressive use of commodity hardware, well built, and like the bootlaces.
  4. South Africa's grid is not erratic or unstable. On a spectrum of how bad it can get, it's just not. At least yet. Sure, if you live in a small town where the municipality is bankrupt and infrastructure is crumbling, then maybe on a local scale this could be true, but as a whole our grid is pretty stable and gives clean power. Once you get to Zimbabwe levels where you have maybe power 8 hours a week (I hear rumours of even less), then grid-tied obviously makes zero sense. And if you simply lose too much money during our own 2.5 hour outages, then the same. But overall, assuming that things don't deteriorate too much in the coming years, grid tied still makes economic sense.
  5. So allow me to go a bit OT here. Ignore if not of interest. The first time I really saw bootloader magic was with something called OS/2. Some of the old people in the room might remember that, it was once the better OS, but usually these things win or lose based on which company has the better marketing team. OS/2 had an interesting concept. When booting, the first stage loader (which has to fit into 446 bytes, cause it has to fit in the first sector of the disk along with the partition table) loads just enough capability to access the disk. At this point it is still in real mode. Then it loads a mini-IFS (installable file system). This gives it access to the file system. You can theoretically boot OS/2 off any type of file system by just swapping the mini-IFS. The mini-IFS has just enough functionality to load the kernel of the OS. Once the kernel kicks off, it kicks the CPU into protected mode and only then does it truly get off the ground. This then loads a full IFS, and there you go. This model was later copied by other OSes, the now de-facto loader for Linux (grub) uses pretty much the same model, and I believe some BSDs had it too. Even windows NT kinda finally grew a bootloader, but of course it never supported anything but FAT and NTFS. The Raspberry Pi is another interesting beast. This thing actually has a GPU and an ARM CPU. When you turn it on, the GPU is running and the CPU is off. The first stage of the loader is in charge of loading a second stage, activating the ARM core... and then continuing. Almost all modern stuff works this way now. Even the Axpert inverter has a bootloader on its chip, so does the BMV, the solar chargers, even the Multiplus. It's just how you do it... back to the 70s.
  6. I kinda assumed that all Axperties running BMVs will do so with ICC and therefore by definition have the cable already...
  7. I'm lazy when it comes to these things. Batteries aren't that sensitive to the exact voltages as long as you charge them properly (ie, exact absorb voltages are more important when you cycle daily. but not so much if you're a UPS). So pretty much, for any AGM, 14.5V to absorb and 13.5V to float. Charge rate set to 15% of the capacity (C20.... C10... not that important). So your settings seems good to me. Perhaps increase charge current to 20A.
  8. Well... this is an Axpert site Which is also why I kinda skipped over it the first time...
  9. That means it's in the bootloader. So some background. These devices all have a two-stage software design. In fact, almost all computers work like this (some, like PCs, have more than two stages). The bootloader is normally a small bit of programming that only does two things: It loads the main program and starts it, or it updates the main program. The bootloader itself is (almost) never overwritten. This makes it very difficuly to brick it, because you never overwrite the bit of code that you need to re-flash it. If the main program is corrupted or not there, the device will remain in the bootloader and allow you to flash it again. This is where you are. I've seen this behaviour before, this difficulty to update. Try using a different mobile. I've had endless problems with a Galaxy S4 mini (running Cyanogenmod), but a much older Galaxy II Note worked perfectly. So did my old Huawei P10-lite, but with LG phones I've only had problems (even on non-Victron stuff). You could also try using VictronConnect on a Windows PC with the VE.Direct cable, as Jaco suggested.
  10. Right, this is where things get a little shocking. So if I assume that the battery arrangement in there is 24V (I have probably about an 85% chance of being right), here is how this will pan out. Generally speaking any panel above 150W will be a 60-cell or a 72-cell module. You can roughly multiply the number of cells by 0.6 to get the open circuit voltage, so the panels you mention will make around 36V to 44V if you just measure them on their own. If you look at the spec sheet of that charger, that's within limits: The solar charger can handle up to 50V. Now comes the interesting part. A solar cell makes its peak power at around 0.5V per cell, so if I assume you have 60-cell modules, that's around 30V, so you can divide 255 into 30 and get the peak charge current, which is likely around 8.5A (but you can look on the back of the panel, it's will show an Imax value). Your batteries are however at a nominal voltage of 24V, and this is where the cheaper PWM controller loses out: The power you're going to get out will be 24 * 8.5 ~= 200W. So you're losing around 20% on the cheaper controller. But that does not matter as long as you get the batteries fully charged. A 100Ah battery does not really want to be charged at more than 15A (around 15% of its capacity), so if you throw those two panels on in parallel, you should be below the 20A rating of the PWM charger and also within the 15A-20A recommended charge current for the batteries. So you definitely don't need more PV (again, assuming I guess right as to the battery capacity). Now the remaining question: Will it charge fully in a day? That's difficult to answer, because lead acid batteries slow down towards the end, which essentially means you want them to be almost full by around noon already so you have the whole afternoon to float them. So you have maybe 4 hours to get 90% of the work done, but you only really have 5 hours of equivalent peak sunshine in Southern Africa, so I would probably not take them lower than 50% DoD because if you do you might not get them all the way back up again. (I'm thumb-sucking most of this... your job to check my math ). That means you have around half of your 2.4kwh available, or 1.2kwh (again, I assume 100Ah batteries in there). If the kids sleep 9PM to 7AM, that's 10 hours, so you can afford to run 120W of stuff. Very crudely calculated. Also, you have to lug around 100kg of lead batteries on your trip.
  11. Aaah I think I know how I will answer this next time (if ever). I'll say that my greatest weakness is that I lie when I am asked what my greatest weakness is.
  12. Aaaah! The old "Please tell me by how much I can screw you" That's almost as stupid as a job interview where you are asked what your greatest weakness is. "Oh, I'm too much of a perfectionist sometimes..."
  13. Since you've already bought the unit, one way to go about it is to simply test it. Indeed, I've also found that simply turning on a fan does wonders for getting rid of mosquitos. A ceiling fan works absolutely brilliant for this. The inverter on that unit might be a modified sine-wave inverter (which is a fancy way of saying it makes a square wave with the equivalent power value), but I'm sure it will be fine for your intended use. Small electrical motors (like those in the fans you want to use) usually don't like this kind of power, and they buzz a little, but other than running a bit warmer there is usually no detrimental effect and it does not seem to cause premature failure, so a week away on holiday is going to be fine. How to connect the solar panels? You'll have to open the box at the bottom. I don't know for sure, but as I recall it has 2 x 12V 100Ah batteries in there, wired into a 24V bank. You will then connect the battery terminals from your solar charger directly to the battery (I would advise that you put a 25A fuse in this line), and connect the PV modules to the other side of the solar charger. To make it easier, go to your local 4x4 place, or Outdoor Warehouse, and get some Brad Harrison connectors to make it easier. Make sure the charge controller you bought can handle 24V. Count the "dots" in your solar panels. If it has 36 cells, it's an 12V panel (actually more like 18V) and you need two of them in series for a 24V bank. If it has 60 or 72 cells, it makes 30V and up and can be used on their own. Of course you need to make sure the charge controller can handle that voltage too. I assume you bought a cheap PWM solar charger, but without knowing more, it is difficult to say.
  14. I pretty much stopped using Facebook "buy and sell" groups. I'm sick of getting "Is this still available?" messages with absolutely zero interest past that. Even adding the text at the top "if this is still here it is available" does not completely cut down on such traffic. There's pretty much a minimum monetary value that has to be exceeded to "pay" for the pain of advertising on some platforms, and I've decided that value is somewhere between R500 and R1000. Below R500... screw it, I'll just keep the thing around and toss it in the bin some day if I don't find a use for it.
  15. Not at all! If anything it ends up rejecting everything including itself (Note, I am talking about materialism as in the philosophical view that matter and energy is all that exists, not about the way of life where you make money the be-all and end-all). To quote something from one of my favourite writers (I really should go back and see what Joseph McCabe was on about to get the whole context, but here it is):
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