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Showing content with the highest reputation on 07/04/2018 in all areas

  1. 1 point
    plonkster

    Multi strings

    Bwahaha. This pans out empirically in my setup almost every day. It isn't just the calibration of the controllers that is at play, an 0.2V voltage drop over a cable is also entirely possible. I have two "V" controllers, and whenever we hit absorption voltage one of them shuts down just about completely. It's charge voltage is set 0.2V too low and by definition no current can flow. See below for an example, watch how the top one just hamba la kaya... But it doesn't matter in this instance. The battery is being held at absorption level, so who cares how it's being done. That bit of a squigly in the bottom graph, that's because the battery got full (lithium's, they stop charging like a plane stops against a mountain), and we went to float a bit later which is why it dropped to zero for a short while. The point though it that the top graph shows my 150/70 charger tjaila'd for the day. And these two chargers are in fact in sync in terms of charging state, because they are part of an ESS system. The difference is that the one charger is a canbus charger which does not support shared voltage sense, while the other one does. (Shared Voltage Sense is a cool new Victron feature btw... you should check it out ).
  2. 1 point
    The Terrible Triplett

    Multi strings

    Logically it makes sense. "Couple of minutes" is that part that gives me the grills. Would I use 2 different makes of controllers on my battery? No. Stems from many many years ago when Morningstar was pushed for answers as more and more people wanted to have 2 or more controllers. First it was a resounding not advisable (and still is for different makes of controllers on same bank) to it is perfectly ok as long as the 2 controllers are identical, set to the exact same settings, each controller on a separate array. Some of the more high end controllers became enabled to be interconnected with cables for even more complicated setups. Any case, please, I am just sharing my thoughts, am not technically minded nor qualified, unless you want me to blow things up, then I am an "Axpert". (tears are flowing!)
  3. 1 point
    Chris Hobson

    Multi strings

    Pump controllers cost tens of thousands of rand hence the experimentation to try and reduce costs..
  4. 1 point
    Chris Hobson

    Multi strings

    I not sure I understand the problem. Both SCCs will be monitoring the same battery bank. Lets for example say the one SCC (SCC A) under reads by 0.2V. The second SCC (SCC V) is absolutely accurate (I wonder why I chose A & V rather than A & B must just be a quirk). We for our hypothetical case have AGM batteries which have a bulk voltage of 56.4V at 25°C and float of 54V. As the sun starts to shine through the smog of Africa's powerhouse both SCCs will be in bulk and delivering the maximum amps (20 Amps each) that the bank can be charged at. At this point in time no problem. SCC V reaches bulk and changes from C.C. to C.V. SCC A thinks the batteries are at 56.2V and continues to deliver 20A and continues to raise the voltage to 56.6V. Will SCC V stop charging? I don't think so. If SCC A raises the voltage to dangerously high levels yes I think SCC V will shutdown but not for a 0.2V difference. Both units are in C.V (absorb) and the batteries accept less and less current since the voltage is constant (incorrectly at 56.6v rather than 56.4V because we have a faulty SCC). After a period of time one of the two SCC will determine it is time to go to float (this being determined by its charging algorithm) and reduce the voltage and the batteries will accept even less current at the lower voltage. If the other SCC determines that one is still in absorb what happens the SCC that has gone to float charges at a slightly higher rate. Eventually both SCCs will be in float albeit at 0.2V higher than recommended. Will SCC A damage the batteries? Yes - not because it is working in tandem with SCC V but because it is inaccurate. This is slightly exaggerated scenario but on could conceivably have a difference of 0.05V between to SCCs. What is going to happen? The two SCC might be out of sync for a couple of minutes. SCCs are not in control of charging, they respond to cues from the batteries in terms of voltage and current and adjust accordingly. So you could have two SCCs charging the same battery bank and the one will be "unaware" of the other. ( A point made in the second video) Gustavo (in Spain) had two SCCs an Axpert and a Midnite Kid - there seemed to have no problems. Incidentally he did correct his battery cabling. https://www.youtube.com/watch?v=x6xdCfquoOc https://www.youtube.com/watch?v=Z3CFhQMZLTw So long as your combined charging is below the safe maximum of your batteries. You are fine. Once into absorb the current accepted by the battery will taper anyway. Perhaps one would set the independent SCC to charge at 80% of what its array could deliver and have the Axpert deliver the balance. Thus one could make use of the Axpert's abilty to charge and power the load . The independent SCC would provide the bulk of the charging.
  5. 1 point
    The Terrible Triplett

    Current Water Affairs.

    As true and sound as the advice and suggestions are re. check your rates and taxes, it is a huge job as you say. Me as an individual would rather spend some of that time and stir with some political adverse post to ensure we meet @gabriel 's request for more "like blaming the da or anc or better yet the khoisan/neanderthal liberation front or whatever". Hold on Gabriel, am waiting for the next juicy political incorrect subject to come across my desk start the next post on. But @ebrsa, truth be told, as the payments increased in the last few years, our bill become less. See, as the rates go up, so I lower our consumption without making things "uncomfortable" for SWAMBO. As such, I am paying less now what I THINK I paid 3-5 years ago. And I am nowhere near some of you guys ito electricity. And water, watch this space. Been washing with rainwater the last few weeks now, with that going to toilets. Not a municipal drop of water went down the drain. On top of my lower contributions, all the Axpert users here have contributed to even more losses in income for even more municipalities, and the Gov, with 15% VAT. :-)
  6. 1 point
    Coulomb

    Axpert 73.00b funnies...

    Light years. I haven't looked at probably 80% of the firmware code, and I find it hard to understand ~30% of the 20% I have looked at (very rough figures). They have very clever code to handle the synchronised relay control, and handling paralleled machines (some with three phase). The contrast with some of the more pedestrian code is stark. It's certainly getting to be a lot of work. There is such a header for the TMS320F2809 based boards; it's a 14-pin JTAG header, and there are standard JTAG interfaces (some inexpensive, some four times the price of the inverter-charger and very sophisticated). I've used that header a few times. No fuse bits are blown, but as of a few years ago, they've started using security, which means we can't read their firmware directly any more . But if someone else writes an open source firmware, they would have little trouble flash programming it. Debugging is always a challenge when you have a high power inverter; just stopping the processor dead (at a breakpoint, say) while inverting or charging could be disasterous. And there is no desaturation protection to save the IGBTs or MOSFETs. For distribution to ordinary users, however, it would be more useful to use a similar upload scheme. Perhaps even the same protocol (with a high speed option perhaps), so that users can bootstrap to the new scheme. It would be a monumental exercise. I'm much less familiar with the HCS08 processor, as used by most of the solar charge controllers and the lower power inverters. I assume that there is a similar arrangement for them. We actually assemble some of the patches into a block of unused flash memory. So there we have the luxury of comments, meaningful variable names, and macros (if we needed them). But even ven those source code patches need a call instruction patched into the original firmware to call the patch, and sometimes a few NOPs need to be inserted (some instructions are two word, others a single word). These latter have to be done by hand. But perhaps a quarter of the patches are direct hex modifications. Usually these are only to NOP out a branch, or to change the value of an immediate operand. We actually publish the .txt file that we use to keep track of the patches, so you can see the gory detail if you really, really want. So we have to know the instruction set; being a DSP, it's not actually intended for use by humans (only by the back end of a compiler). There are remarkable gotchas and inconsistencies in the C2000 instruction set. Weber also wrote a spreadsheet to calculate the checksums for us. The tool that gets most use is Windows Notepad (I kid you not). We use TI's Code Composer Studio to assemble those patches or partial patches that have assembler source code. I suppose one day we might write part of the patches in C. And of course, every time there is a new firmware version that we get a hold of, we have to find the addresses of all the patch locations; every one of them will have moved.
  7. 1 point
    ebrsa

    Current Water Affairs.

    What you want to check is whether any tariff or rate, but particularly the water tariff increased after 1 July 2018 and 10 November 2018. Of course you rates and tariffs will change on the July account as that is the first month of the financial year. Compare that with the tariffs approved by your council as reflected in the tariff list. The tariff list and many other documents can be downloaded from your municipality's website. I compare other municipalities' budgets yearly with that of Swartland, where I live, as chairman of the Yzerfontein Residents' Association, an onerous task but if one does not take on the council about some unacceptable decisions they will run wild. I had an hour and a half meeting about our water tariffs with the mayor, municipal manager and financial director about a week ago and this matter is far from finalised. These officials out here in the rural areas still talk to taxpayers but I guess it will be an uphill struggle in a metro like Cape Town. Besides there is absolutely no assurance that they will always be right, so taxpayer beware. We have proven them wrong on more than one occasion which makes all the many hours of research worth while. Like I said in my previous post, download the ministerial exemption from Section 28(6) of the MFMA from Treasury's website and see if your municipality is mentioned. If not and their water tariffs increased above the approved tariff for the financial year, they acted in contravention with law unless they have evidence of exemption. We are having enough irregularities where the public purse is concerned to allow it where we could possibly make a difference. We taxpayers are after all the folks who fork out the money to be managed with due responsibility by those we have entrusted as custodians of our money.
  8. 1 point
    gabriel

    Current Water Affairs.

    JAWOHL!
  9. 1 point
    The Terrible Triplett

    Grid Tied Inverter

    Give that supplier a Bells!!!
  10. 1 point
    Allen Hobson

    Grid Tied Inverter

    Thank All for the Replies and Info... Supplier is going to take back the 3 axperts and supply 2 X Solis 3.6kw with limiters and wifi etc. Need to rewire the 7kw array into 2 strings in series.
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