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Coulomb

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Coulomb last won the day on February 3

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About Coulomb

  • Birthday 05/11/1958

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    Male
  • Location
    Brisbane, Australia
  • Interests
    Solar energy systems with storage; firmware for inverters and chargers

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  1. That's a "communications (from battery) lost" warning (not error). I believe it's normal for the first minute or so, but should not happen after that. Do you have the appropriate magic cable (not a straight-through ethernet cable)? Correct ports at both ends? Correct DIP switch settings?
  2. Just use the one earth terminal for both AC-in and AC-out. The earth wires are often not as high in cross sectional area, so jamming two wires into the same terminal is doable. To me, this is cost cutting gone too far. If they do that, what other short cuts are there inside where it's far less visible?
  3. I note that this isn't a real Axpert, it's a clone. So the wiring for the RS-232 port depends on how accurately they copied the 2014 Axpert (I run two genuine 2015 Axperts (PIP-4048MS) with similar specifications except that the 2015 models have the USB as well as the RS-232 serial ports). It's 99% likely that they use the same pinouts as a genuine Axpert. Hopefully it came with an RJ-45 to serial cable, like the Axperts it was copied from. You should then be able to use a standard USB to serial adapter to talk to it.
  4. Please be more specific. 4 kVA or 4 kW? PF0.8 or 1.0? Scc 145 V or 450 V max? So these arrays have slightly different panel specs? How many in series? Interesting. The act of disconnecting might be causing it to do a long ramp, and with the typical Axpert overshoot, it may overload the SCC for just long enough to "get it over the hump" to pull the array voltage below the ramp down voltage. But without additional information, that's just a guess. "like this" as in the two arrays in parallel? What were the specs of this RCT inverter-charger?
  5. I'd say most of it is because of your excessive Voc: 45.85 x 3 = 137.6 V. That's over 130 V, where the SCC starts ramping down maximum power (assuming that 24 V SCCs behave the same as 48 V SCCs; it could be lower than 130 V). That means it has less than full power to pull the panel voltage below 130 V, so that it can then operate at full power. The SCC might be reporting as "not OK". You also have a lot of PV for your model, 128% of rated maximum. This makes the SCC a bit touchy (a small change in PWM results in a larger than expected change in charge current). I don't know if that would lead to lower PV use. You can probably get away with this. So you should rewire your panels for 2S3P instead of 3S2P.
  6. I don't believe that there is a fuse there. The display is a modular thing; IF you can get a replacement part (start with the people that supplied your inverter), it should be easy to replace. Likely it will be the whole display / buttons / LED that you replace. Or maybe, with decent monitoring software, you can live without the display altogether.
  7. Fully charged is getting to around 56 V for long enough for the charge current to drop to about 6 A. Then when the charge stops, the battery voltage should retreat to about 54 V, with nearly no charge current (roughly ≤ 2 A) required to hold it there. That's not fully charged. When the inverter thinks it's fully charged, the middle green LED should be on solid (this indicates it's at the float stage, and is aiming to keep the battery voltage at the voltage in setting 27).
  8. I'm starting to think that a lot of the "dips" problem are exactly this. People are using crazy high absorb/bulk voltages, and Axperts are prone to overshoot their voltage targets, so the BMSs may be disconnecting. When they do, the battery voltage seen by the inverter would plummet. By the time the BMS has reconnected, it may be that the inverter has detected quite a large battery voltage drop. This is a trigger to go from float stage to bulk stage. Axperts are a little unusual in that to do this, they first go to "no charge" state for some 15 seconds, then take a few seconds to check that the PV input is present and stable, then stay at something like 1 A (battery-side) charge for 15 seconds, then slooowly ramp up the charge current over perhaps another 15-30 seconds. The result is that there can be a minute or so of no or very low PV charge current. This can overshoot the target battery voltage on that initial ramp, even though it's so slow, so the whole process could repeat. I believe that this happens with utility charging as well as with PV charging. Sometimes, installations use 3S of solar panels where 2S would be better, and this can cause additional delay because with little to no charge current, the panel voltage goes up; once it gets close to 145 V, there is little power that the solar charge controller will take, so it takes a while for the panel voltage to decrease below 130 V where full power is allowed. That's for SCCs with the 145 V max PV limit; I suspect that something similar may happen with a long string of panels approaching the 450 V or 500 V limit of other models.
  9. That's weird. I note that the charger source priority, as well as the maximum utility and total charge current settings (settings 16, 11, and 02 respectively) are settings that don't automatically transfer from one machine to another. So it may be that the slaves have disabled utility charging, or set it to only 2 A. I would have thought that the master would still charge from utility when directed, even if the slaves don't.
  10. Are you saying that even after doing the above, the warning 69 did not go away?
  11. I assume you mean that you can count on at least 3.3 kW of solar power for the 4 hours centred around noon. That doesn't leave much spare for the rest of the house, so the battery may have to work hard. That's too small for a 5 kW inverter working hard. You need at least 2 2.4 kWh modules, preferably more. Even if you watch the power levels pretty closely, you can be surprised by a sudden cloud cover, and I have no idea how fast you can just turn down the power requirement of your rig. I assume that just switching off the power isn't going to be an option. LED lights do seem to be sensitive to instantaneous RMS voltage, so this is probably normal, if you're talking about switching from line to bypass modes. In normal line mode, it's smoothly blending AC-in, PV, and battery power, right? Absolutely.
  12. I suppose if you switched from one source at 30° past peak, and switched really quickly to the other source at 30° before peak, you might get a small RMS surge. But switching takes of the order of 10 ms, which is half a cycle, so the above scenario isn't realistic. I'm hazy how the whole synchronisation and relay switching thing happens. I've not been able to make much sense of reading the firmware in this area either.
  13. I did forget about bypass mode, and the desirability of switching between two sources (inverter output and AC-in) that are in sync and roughly similar in voltage. I don't agree with the "incredibly dangerous" part, I'd say more "highly desirable". Given this need for synchronisation, probably the same generator quality restrictions apply. I think you still want the PFC feature, otherwise the peak currents can get insane. But maybe turning off setting "bypass function" to "forbidden" (setting 23 to ByF) signals to the DSP that you don't care about synchronising to AC-in. Perhaps you could try this for a while, and see if the input and output frequencies differ. This setting has different options and terminology than the equivalent setting on other models (still setting 23, but called "overload bypass" on non-King models).
  14. No. That's certainly possible. There are clues in the firmware that suggest that the AC to DC converter is a "PFC stage" (Power Factor Correcting). That possibly means that a fairly simple chip has to follow the voltage envelope that attempt to make the instantaneous current follow that envelope, while still averaging (with rectification of course) a target current. Such a simple chip might not even have the ability to tell the DSP "help, I can't cope with this messy waveform, make it stop!". The key thing is that nothing has to synchronise with the AC input. If the PFC can't follow the voltage well, the power factor is lower than desirable, but no big deal. If a system has to synchronise with the AC-in and fails, quite serious erroneous power flow can result. So my guess is: yes, I agree, it may be able to cope with cheap generators much better than other Axperts. On a quick search, I don't see any particular generator requirements for Kings, although the MPPSolar site has the same generator requirement PDF as other models (that may be a cope and paste error on the web pages, though).
  15. Yes. My understanding is that it can bypass ("pass through") 40 A like the other 5 kVA models, so that's some 9 kVA, over 7 kW with a typical power factor. It can do this continuously.
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