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  1. So I did that... last time I saw that image I ignored it, assuming you had the overcurrent aspect covered. I looked up the spec sheet for the KRC3... it's has no overcurrent protection. You better fix it... ABB makes some nice RCBOs (that do both).
  2. Hang on, not so fast... You must have both 1) overcurrent protection, and 2) residual current (aka earth leakage) protection. You do get combination overcurrent/rcd devices, but they are quite costly, so in most cases your house will be fitted with individual breakers, a 60A main breaker for overcurrent protection, followed by a 30mA RCD. It is unlikely that you have overcurrent protection on that RCD (due to cost factor), so it is NOT as simple as just removing one of them.
  3. The danger is that you could end up pushing the voltage up, then down, then up, then down... etc. This might not matter too much when you're not feeding your excess DC into the grid, but when you're feeding DC into the grid (more common overseas), then this causes the Multi to go into a charge/discharge loop. So sometimes you need to dampen/low-pass/exponential filter it a bit. Exponential filter usually works well.
  4. To be fair, I've not actually tried it. It is a theoretical concept. The idea is to have two modes, so to speak. 1. In normal mode, all your cells are balanced. You charge until the charge voltage is 56V, and because the cells are balanced, all of them end up around 3.5V, give or take. 2. In "balancing mode", your cells are not perfectly balanced. One of them is beyond 3.6V. You then lower the charge voltage so that this cell does not rise even higher. If you set the charge voltage to the sum of the present cell voltages, then in theory no further charging happens. If there are calibration differences, then maybe you end up pushing a little bit above 3.6V per cell, but that should be fine. You can go up to 3.8V without any danger. To use an example from real battery I had. This battery reported its lowest cell as 3.35V, and the highest would go over 3.8V. Using some simple math, I figured that 3.35*15+3.8 = 54.05V, and this was precisely what we observed: The battery would raise alarms when we went over 54V. Using my method, you'd aim for 56V, and then the moment you see a high cell (as you near 54V) the BMS would drop the charge voltage to 54V. This prevents the high cell from going over-voltage. The BMS can now take its sweet time shovelling charge towards the other cells. As the other cells rise, the charge voltage will slowly creep up, until the balance is restored. Then you can go back to "normal mode". The things that will cause some issues: delays in measurement. If the voltage measurements are several seconds old by the time you get them, you may not be able to react fast enough. LFP cells above 3.55V spike up really quickly. Therefore, running a control loop based on the highest cell, where that cell sits between 3.6V and 3.8V, may be a fools errand unless your measurement delays are low enough.
  5. If you get this right... well... you should send your CV to some battery makers. Cause few of them get it right...
  6. They use a VFD/VSD (variable speed/frequency drive). They can drive the pump slowly when you don't have too much sun (by changing the frequency), or at full speed when there is more sun. They are a kind of inverter that work directly from sunlight, which they can because they can adapt the speed of the pump to the available sunlight. This kind of setup should be way more efficient than putting down batteries and inverters. Talk to @anotherbrownbear, or contact All-Electrical in Port Elizabeth. They specialise in this stuff. With that concern out of the way, you can probably get away with the usual Voltronic money-savery...
  7. That's a shame. Cause you can go a long way if you have those dry contacts, and it is usually significantly cheaper than full CAN-bus comms.
  8. Does this BMS perhaps have dry contacts to indicate stop-charge and stop-discharge conditions?
  9. can1 351 [6] 14 02 50 02 C8 05 can1 355 [4] 5F 00 63 00 can1 356 [6] 77 13 A9 FE 0B 01 can1 359 [7] 00 00 00 00 04 50 4E can1 35C [2] C0 00 can1 35E [8] 50 59 4C 4F 4E 20 20 20 That's a list of all the unique stuff a Pylontech battery sends. I filtered out the duplicates so you can see just the important bits. 359 ends in 0x50 0x4E, which is the ASCII codes for PN. That's how you identify a Pylontech (this is in their official documentation, I'm not disclosing anything secret here ). There may be some issues around legality if you send PN without being a Pylontech battery... I mean in commercial endeavours at least. The 04 before the PN is the number of modules in the battery. The 4 bytes before that are the alarms and the warnings (the battery I took the dump from is showing no issues, all is zero). This is just about the only way in which Pylontech differs from some of the others. They use 359. The others use 35A. Also note that 35E spells PYLON followed by three spaces.
  10. If you had this paired with a 3kVA Multi, it would have been a perfect combo
  11. Yeah. This is a bit different to lead acid. With lead acid there is a recommended charge rate, and coming in too low is a problem. With LiFePO4, there is a limit which you should preferably not exceed (1C), but charging slowly is much less of a problem. So in this case you can just throw the full 70A from the inverter/charger into the battery and not worry about it (it is under 1C). But as Louis said, discharge is another matter. If the BMS wants you to stay under 80A, you risk a battery disconnection with sustained power levels above around 3.6kW (if we leave room for a bit of losses).
  12. If you turn it off, it defaults to 100% (ie, stop when the battery is full). In practice, it never stops at all, it is essentiall the same as keep charged for as long as the time window lasts. That is also why the "stop at" box stops at 95%. Otherwise there'd be two ways to get 100%... I'd expect that the mere bit of fluctuation caused by ESS should already be enough to make the battery think it is not idle.
  13. The gentlemen means firmware, but it is certainly a very amusing mistake
  14. Is it a Multiplus? Usually the main reason, for first time users, is that the Multi is in passthru mode (it shows it on the screen) because there is no grid meter. The default config of the GX device is to expect a grid meter (Carlo Gavazzi). If you don't have one, you must disable that option in the ESS menu. After that, setting the ESS mode to "Keep Batteries Charged" should be enough to get it charging.
  15. Depends. If you have a managed battery (ie the BMS can communicate with the CCGX using a can-bus connection), then the battery is in control of charging. Otherwise the Multi is in control (so whatever you set up in VE.Configure is also used by the solar chargers). It is however a good idea to set the MPPTs to the same values, just in case they end up running standalone at some point. With a 16s setup, there is usually not too much danger. With a 15s setup (eg Pylontech), people often forget to lower the voltage, and then the first time the solar chargers end up standalone they overvolt the battery 3.65V is very VERY highly charged. I would suggest you aim for 3.5V or max 3.55V per cell. Very little extra energy is stored above 3.45V per cell. As long as the voltage is high enough so that the balancer in the BMS can do its job, there is no reason to run at such high cell voltages. 56.8V is indeed a better voltage than 58.4... but I'd suggest 56V or even lower (but no lower than 55.2V). The BMV does better SOC tracking than the Multi. If you plug it in, the SOC of the BMV will be used in the system. My suggestion is to use it.
  16. Well of course you can install the BMV and get good data from it, but if you actually want to use the data to control an inverter, then you'll need some kind of middleware. Now some of the Growatt's are work-alikes, so it could be that ICC can indeed control their priority setting... I don't know and frankly I don't care too much either
  17. Way too slow. Even at 20ms the occasional sensitive bit of kit will drop out.
  18. In this case, the solar chargers get their charge voltage from the Multi. So whatever you've got set as the absorption voltage on the Multi (in VE.Configure) minus a little bit (0.5V or so), is the voltage you want to use as "charged voltage".
  19. The changeover is simply so that the inverter can be bypassed. It moves the loads away from the inverter and back into the grid. This allows you to work on the inverter, do maintenance, replace it even, etc... without the wife and the kids asking every 5 minutes when the power/internet will be back on... (Honestly, it is amazing how modern man cannot go 5 minutes without such luxuries... ).
  20. That's something I don't have complete clarity about. In principle, all that is required is that your changeover must be interlocking, that is to say, it must be impossible for both sides to be engaged simultaneously. A contactor (which is a heavy duty kind of relay) with two NC (normally closed) and two NO (normally open) contacts, usually would be sufficient. The physical separation makes it difficult for both sides to be engaged simultaneously, and if a contact were to weld close, it would be impossible for it to release and engage the other side. With that said however, most of the examples I've seen of building changeovers with contactors use two contactors, wired in such a way that it is electrically interlocked, but also with a physical lock-out. See here for example, this is for using contactors to reverse a three-phase motor, but the principle is still the same. If you look around a bit you will find a similar method for star/delta 3-phase motor starters. So I have a gut feeling there must be a reason for using two and not just one... But what @Richard Mackaysays is true as well. Most inverter/chargers have a changeover switch built in already. But if you lack this, then you'll either have to throw some contactors at it, or buy a dedicated unit. In all cases, make sure it has the required IEC/SANS rating.
  21. Aaah, then @Coulombis your guy. I know the basics of how these things are done -- it is done the same in Victron inverters -- but I don't know what happens if you load the wrong firmware or get it bricked.
  22. I have no idea what inverter you have, but I can tell you that generally these things are developed so that there are two parts in the software: A small "bootloader" at the beginning of memory, and the main firmware after that. The bootloader is usually never overwritten, and the part that allows flashing the main firmware is in the bootloader. During normal operation, the bootloader will simply check that there is valid firmware following at the right address, and then tell the CPU to load the first instruction and run it. If there isn't valid firmware, it will remain i the bootloader. This will usually allow you to flash it again, or perhaps flash back to an old version. It is quite normal for the unit to appear dead at this time: The main firmware is not running, so quite often none of the LEDs will turn on or anything.
  23. Aaaah, the ongoing game of defining your terms. The way I see it, is the whole thing (all series/parallel strings together) make up one large battery. The battery will consist of one or more modules (in Pylontech land, each 19" rackmount box is a module), and each module will consist of multiple cells. When you have multiple modules making up your (one) battery, there is generally some way in which the individual BMS components manage the whole. With Pylontech batteries, this allows a module to disconnect from the DC bus, but leave the rest of the battery up and running. If you had one large module, this disconnection event could cause the inverter to turn off. If you had two small ones, the other module remains online. In other words, having more than one module adds some redundancy.
  24. Those are in /System/MinCellTemperature, /System/MaxCellTemperature, /System/MinTemperatureCellId, /System/MaxTemperatureCellId, /System/NrOfModulesBlockingCharge, /System/NrOfModulesOnline, /System/NrOfModulesOffline, /System/NrOfModulesBlockingDischarge, /InstalledCapacity, and /Capacity. If your battery doesn't have them, just leave them out. They are optional paths, for diagnostic purposes. An even more interesting project would be to do clever voltage control. As soon as you have a high cell (one that is above 3.6V, set the charge voltage to the sum of the voltages of all the cells (or some maximum safe value, whichever is lower). Theoretically you've now created the perfect condition for the balancer to do its job, shoveling charge away from the high cell. Over time, as the lower cells pick up, this will cause your charge voltage to be raised as well, thereby maintaining conditions for the balancer to work well. Using this method, you should never have to adjust the maximum charge and discharge currents. You only adjust those as a last resort. Of course, normally, the BMS should work out these voltages, but in this case I think it might be interesting to implement some smarts yourself, since you have the luxury of having all the cell voltages. Edit: A figure an explanation may be needed about the capacity paths. InstalledCapacity would be how much is actually installed, while available capacity is how much is online right now. In multi-module batteries, those values might be different when one module disconnects itself for whatever reason. In your battery, they will likely just be the same value, or you may choose to show only the Available capacity since that's what the BMS gives you.
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