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phil.g00

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Everything posted by phil.g00

  1. @plonkster, I look forward to the video, but aside from a blown MOV, I think you're chasing your tail.
  2. They are R10 a pop. If the leakage current graphs are to be believed you'll need around 10 millionish of them for 20mA. Rather made a Hollywood blockbuster
  3. The default "000000" password is probably unchanged as well.
  4. My system is atypical, I actually use voltages quite a bit differently than most as I have an offgrid system and a grid tie system on the same bank along with ac coupling. My Outback charging is set slightly higher than I need to charge the batteries, and my Victron will not let the voltages rise, this forces power to be exported and my MPPT's work all day long into the battery and loads. The Victron's export function keeps the voltage down at proper charging levels. I don't see high voltages, at least not because of the outbacks. Before I had the present arrangement though, (barring the faulty Outback I spoke about), they all behaved though. I see high voltages during load -shedding until the other Victron system shuts down the PV inverters, but that's not the outbacks' fault.
  5. They look alright to me, equalize is off right?
  6. I've been looking at a lot of BMS's in the past few days, if I'm not getting it confused with another product offering. Orion uses a two hall effect sensors in one package. One of them is dedicated to being accurate at small currents, which then switches to the other when the currents are higher.
  7. I scrapped one unit that was given to me, because it didn't respect the voltage settings and over-volted the battery bank. I am not talking momentarily, I am saying it charged at the wrong voltage constantly. Momentary voltage spikes on LA batteries in the order of what 6 or 7V wouldn't bother me, although I can say I've seen them, but I haven't really looked. I don't think Outbacks are suited to Lithiums really. Coincidentally, I was just discussing DC voltage spikes on another thread, and how they can be a result of inertia in the feedback loops in response to step changes in load say. The MPPT may also be paralleled with other equipment, just because it is presenting the measurement doesn't mean it's the culprit either. But by momentary that's what I mean, not multiple minutes. Perhaps, list your settings here, there maybe something that jumps out. - BTW do you have temp. compensation?
  8. You can overcome attempting to get the meter to zero by setting a marginal in feed value. The control loop is fine for an accumulation of small and gradual changes, it's that sudden step change that throws it a wobble, when that margin is not sufficient. And obviously its not prudent to set that margin sufficiently to cater for step changes or we'd be constantly drawing power from the grid unnecessarily. Yes, I appreciate the dilemma.
  9. I'd have to read the documentation, but I think the sampling rate is in the kHz, least-ways that's where I'd expect it to be for PWM.
  10. No, I was drawing the analogy of losing the grid ( a step change in AC feed-in conditions) to a sudden change in load ( another step-change in AC feed-in conditions) and the inertia inherent in the feedback loop. Maybe you are right about this, but I don't think its cut and dried, increasing voltage on one side of a transformer is mirrored on the other-side. Really need a scope trace to say for sure.
  11. AFAIK you have to send the units back to Outback. There is an Outback forum on the web, probably the best place to ask. I have Outback's myself (FM 60's and 80's), but they do what I need them to do so I haven't touched them.
  12. To this I say "maybe, maybe not". Although again the Victron documentation (ala the 1:1 rule) the batteries also experience a voltage spike and I would expect it. I believe, (though like I say, I am not prepared to prove it), that clipping that DC voltage rise instantaneously will have the same affect as doing it on the AC side as we are dealing with a bi-directional device. I agree that messing about on the AC side a fools errand, but the DC side that's a battery voltage usually somewhere between stable limits and of course no phase differences to contend with. So its far easier to deal with. I did caveat my proposal, but it MAY work, and it is an off the shelf solution, that is designed to dump DC energy very quickly. Essentially, what it does is instantly present a DC load absorbing that DC voltage spike, giving that feedback loop time to respond.
  13. @plonkster, I am aware of the of circumstances under which this occurs, but it stills boils down to a sudden change in potential difference ( voltage) between the grid and the load side. By definition power cannot flow without a potential difference across the connecting impedance, with AC this can be a phase difference or a magnitude difference or both. Power flow is not a cause it is a response. The connecting impedance is a constant, the current flow has changed, therefore the voltage must have changed - Ohm's law. It happens too fast that the feedback loop cant keep up, I know. Which I why I proposed what I think is the fastest clipping mechanism.,( and does change the impedance). (If I recall this voltage spike is also in Victron documentation and is the basis of the 1:1 rule).
  14. I think this MAY work. Morningstar makes a PWM charge controller, well actually two a 60A and a 45A version. ( Not the Morningstar MPPT versions !) This unit can also be used in load diversion mode. What is that you ask? It is generally used for wind generation, where the wind turbine is connected directly to the batteries. Generally the battery voltage clamps the wind turbine voltage, but in high winds the turbine voltage wins out. That is when load diversion steps in, and it a PWM fashion at a certain threshold the excess voltage is bled off into a rated dummy load. According to morningstar they do not have a rated time for how responsive this feature is other than to say it is pretty much instantaneous. Outback MPPT's have a similar feature, but their PWM output must control an SSR onto a dump load. You are feding back into the grid because of a short term voltage rise, this MAY be able to prevent that. I do not have this issue and subsequently will probably never prove/disprove this theory. But, for someone that it's becoming a real PITA, it maybe worth experimenting.
  15. As far as I know that is a send in job.
  16. OK, I have a victron system, and I eventually want to go big with a DIY LiFePO4 bank with the full super duper BMS at that time. In the meantime, I intend to build a 16S 280Ah bank to play with and get a handle on this. To that end: Victron inverters have a low voltage load cut-off setting and is capable of dealing with charging the lithiums from the grid. My BMV is capable of SOC tracking and of a "high voltage" relay output, I can use that to cut-off charging like a two wire BMS and drive. I have Outback MPPT's, they can be set, but ultimately solenoid protection so I have to dream up something for that, but that doesn't seem too complex a job. Because I had 48 (4S16P) 12v lead acids, I have a 16 HA02's, 3.6V is one of there stated capabilities. (Probably vastly overkill balancers). I also have 48 tiny little digital voltmeters that I have across each of cell's already. No fancy bluetooth, but a glance tells you what you need to know. Temperature shut off is not an issue I'll have to deal with. I think @plonkster, I probably have the making of a rudimentary BMS re-purposing what I've already got. Thanks for breaking it down into bite-size chunks.
  17. You might consider this arrangement, with the string electrically made up like this. So that the unshaded string works much longer. It maybe more practical that vertically mounting them with special mounts.
  18. And you can work on the half East + the half West being 150% of the MPPT rating or to state the converse you could use a smaller MPPT.
  19. @RikH, You were very quick, apologies I misread your post. You'll see mine was edited within the minute. I am so used to hearing people say that all the strings need to be at the same slope. Which is not at all what you said.
  20. If the strings are standard and the panels of each string are at the same slope and direction, then you can mix and match to your hearts content.
  21. @smurfdbn, Apologies I see from your profile this is a new system and you wont have any historical data. So it was an unfair challenge. ( I was just replying and I see your reply came in). Yes, I was about to say that anecdotally I would expect to get another string on the roof and vertical panels and still not clip. I started out like everyone else perfect tilts and theoretical limits. Now I mix and match the strings of any direction and tilt so that I get the MPPT working all day, without clipping at noon. Doubling the theoretical number of panels can sometimes be achieved, certainly an extra 30-50% PV inverters for AC coupling are an interesting addition ( at least the 2 MPPT version I have is). It has a 3kW max AC output, but can accept 2kW DC input on either MPPT, I can't remember how many E/W panels I got on that, but it was a lot. I have been growing this system for a few years now down in SA for my family, I cant even remember how many panels there are any more. I generally add a pallet a year when I am on annual holiday. There is a pallet waiting for me, but COVID put the kaibosh on me travelling. There might be 2 pallets to go up by the time I'm there.
  22. I don't think your historical data will bear that out. Data trumps theory. Like I said I've done this exercise many times and you will be surprised how how extra PV you can add before you clip. How much clipping is acceptable is another debate as well.
  23. I think you're missing the point, the point is you can get more panels/MPPT regardless of the size of MPPT. What is you could get 6 or 8 panels on that 100/20 MPPT and make more kWh/day?
  24. In Ireland, most days there isn't a blue in the sky. The two days I like the most are St. Patrick's day and summer.
  25. Just as a matter of interest, and to have the resources on the same thread: https://www.researchgate.net/publication/241076784_Increasing_the_solar_photovoltaic_energy_capture_on_sunny_and_cloudy_days This study shows that a perfectly tilted panel produces twice the power of a flat panel on a sunny day. So having two panels ( flatish/wrongly angled/tilted) instead of one sort of evens that out. It also goes on to say that a flat panel produces 40% more than a perfectly tilted panel on an overcast day. So two flat panels produce 80% more power than a perfectly tilted one when is overcast. An overcast watt is worth far more than a sunny day watt.
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