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  1. Thanks
    ___ got a reaction from Marius De Kock in Youda's off-grid LAB   
    Yup. CAN-bus is a BUS. It's two wires running from the one end to the other, with 120Ω terminators at the ends, and many modules can connect to the CAN-H and CAN-L of this bus. There is a whole arbitration and collision avoidance protocol, and everything essentially waits for a gap and then they send their data.
    It's a bit like those old 10base2 Co-ax network cable setups (anyone remember those, or is it just me who is getting old?). Or perhaps another analogy, it's like your television RF cable... you can throw a splitter on it and add another tv at te end.
    The only thing you have to ensure is that the bus is terminated at both ends. Often there is already a terminator built into the ends (sometimes there is a DIP switch to enable/disable it), and on a short run one missing terminator usually doesn't break the bus... but it's a good idea to ensure you don't break the termination.
  2. Like
    ___ got a reaction from Marius De Kock in Youda's off-grid LAB   
    Preach it brother! Absolutely agreed.
    Yup, and unlike some of the other more commonly demanded hardware, these are not always cheap. Your options are:
    1. Rpi with a MCP2515+MCP2551 hat, probably your best bet.
    2. Same chip-combo, but with SPI header that you just wire to the relevant pins on the Rpi/Arduino.
    3. Arduino with the same chips on a shield.
    4. Same arduino setup, but run the slcand code so it shows up as a serial-can device on linux, ie the arduino becomes a usb interface to can-bus.
    5. A USB-can chip, such as the CANable or Kvaser (very costly).
    The canable would be my choice, except that it's still 30USD, so cost-wise the the hat/shield options will probably win. Aliexpress shows a few 15USD options, but there is no telling if they are any good.
    Cheap "canable" interfaces... that's what we need.
  3. Like
    ___ got a reaction from Tim003 in Fuse and Quick disconnect between Pylontech battery and Inverter   
    Why would you take the chance? But okay, you're right, I'm arguing the sensibility and you're arguing the legality... so here goes...

    That's from a draft copy of SANS-10142-1 that has the new DC bits added to it. It says you MUST have an overcurrent device in place. Does not have to be a fuse, can be a breaker, but it must be able to interrupt the full short circuit current of the the battery (which would be a very hefty breaker).
    The insurance company will smack you on the letter of the regulations. Put the damn fuse in 🙂
    What is also interesting here is how ground-faults are avoided. The cable between the battery and the protection device (fuse) must be kept as short as possible, and the positive and negative cabling up to the fuse must be kept separate. They are clearly trying to avoid fault conditions on the wrong side of the fuse. When you do this, you need a battery fuse only in the positive line, since ground faults are now unlikely (it would have to happen in the very short cable to the fuse on the positive side).
    Edit: Also note "NOTE 3", which already refers to the battery protective device, aka the BMS.
     
  4. Like
    ___ got a reaction from melvin phuti in ECU CBI Interesting device and how would one connect   
    It's essentially an internal load-shedding solution to keep your own peak consumption down, by ensuring that two high-consumption appliances are not on at the same time. Eg Stove and Geyser. These days, a function like this could be integrated into something like a geyserwise.
  5. Thanks
    ___ got a reaction from CCC Energy in Connecting a Carlo Gavazzi ET112 to Victron CCGX   
    This part often causes confusion and people wonder why that fuse is there. Let me see if I can explain.
    That neutral wire, which would normally be black in colour, carries only the current required for the electronics of the meter itself. The red wires between terminals 1 and 2, they carry the big stuff. Since that black wire only carries a few milliamps, it does not have to be a very thick wire. It can be as thin as 1.5mm^2. And under normal conditions, that would be all that is ever needed. But you have to cater for what happens under not-normal conditions, aka fault conditions.
    Under a fault condition inside the meter, that meter might be dead-shorted from either terminals 1 or 2 to neutral. It is unlikely, but you have to cater for that. In that case, you must have overcurrent protection for that thin black wire, so that the wire itself does not turn into a small heating element that burns down the house. That's what the fuse is for.
    The fuse just needs to be sized for (or smaller than) the wire. In this case something like a 5A fuse will be more than sufficient. It is less than the wire can carry, so it protects the wire, but way more than the meter will ever need to operate.
    But... you can also just leave the fuse out. But then you must size that black wire for the full current of whatever the upstream breaker is. Since this meter is usually installed right after the big 60A breaker that feeds the house, that black wire must be sized for 60A then, that is to say, it would have to be a 10mm^2. This is what I see most installers do, they just use a thick enough black wire.
  6. Like
    ___ got a reaction from CCC Energy in Mersen battery disconnect - large cables   
    I have never quite understood how you are supposed to get a cable into them. I always cut the plastic to get the cable in. Don't like it, but until someone can tell me how it is supposed to work, that is what I do.
  7. Haha
    ___ got a reaction from hoohloc in Backup ups   
    Dude... I once saw a motorcycle advertised on gumtree. Beautiful machine, almost brand new. The seller explained that his reason for selling is that apparently "Do whatever the f... you want" doesn't mean what he thinks it does.
  8. Like
    ___ got a reaction from NoordSolar in Recommend me some batteries for solar to replace existing lead acid deep cycle   
    Yeah different BMSes have different expectations of the hardware connected to them. Some BMSes get very upset and disconnect their DC protection relay/FET easily if you don't stop charging quickly after it has ordered you to do so.
    In my experience, if you keep your battery voltage BELOW the voltage where the BMS activates its protection features, and if you have a large enough battery so that constant charge current interventions is not necessary, then you don't need communications with the BMS. If anything bad happens, the BMS shuts off the power and the entire house goes dark. Oops... let's not do that again 🙂
    There is however one very useful feature that comes from BMSes that can do comms, and that is that they track SOC. If you already have another way to track SOC (eg an inverter that has this built in, or a BMV), then you don't need to use the BMS for that. SOC is always an estimate, and even the BMS gets it wrong (I have examples of use cases where a BYD battery gets it spectacularly wrong), so using your BMV-7xx is really not a bad alternative.
    But ideally you want a BMS that allows you to regulate the voltage and not constantly mess with current limits. If you just aim for 3.45V per cell, it should run like a conventional lead acid bank...
  9. Like
    ___ got a reaction from YellowTapemeasure in Youda's off-grid LAB   
    Preach it brother! Absolutely agreed.
    Yup, and unlike some of the other more commonly demanded hardware, these are not always cheap. Your options are:
    1. Rpi with a MCP2515+MCP2551 hat, probably your best bet.
    2. Same chip-combo, but with SPI header that you just wire to the relevant pins on the Rpi/Arduino.
    3. Arduino with the same chips on a shield.
    4. Same arduino setup, but run the slcand code so it shows up as a serial-can device on linux, ie the arduino becomes a usb interface to can-bus.
    5. A USB-can chip, such as the CANable or Kvaser (very costly).
    The canable would be my choice, except that it's still 30USD, so cost-wise the the hat/shield options will probably win. Aliexpress shows a few 15USD options, but there is no telling if they are any good.
    Cheap "canable" interfaces... that's what we need.
  10. Like
    ___ got a reaction from Boerseun in Mecer 1200va not opening garage door   
    I had one of those... but it broke way back in December 2012. This is what the big worm gear mechanism looked like:

    These door openers have a normal 230VAC induction motor, and as a result it will have somewhat of a start spike, generally about 5 times its nominal rating. I suspect that's the issue, it simply overloads the inverter.
    I have since thrown the remains of it away, but a it of googling indicates it has a 0.5 horsepower motor, which is just short of 400W. That would need a good 2kw kick when it starts. While many inverters (including the voltronics) can handle a 200% spike for about a second, I suspect your's is JUST a tad outdone by that motor.
    A new low-voltage motor is around 2.5k and well worth it imho.
  11. Like
    ___ got a reaction from Boerseun in 3 Phase generator connection   
    No, that's not going to work. The inverter wants to close its transfer switch and connect the input to the output. The outputs are tied together in a single phase system, but the inputs are 120 degrees apart with 230VAC between them. In all likelihood the inverter will refuse to use the AC input, but it could also blow things up if you try this.
    You'd have to either reconfigure the inverters into a three-phase system, or get a separate three-phase charger.
  12. Haha
    ___ got a reaction from Louisvdw in Is it a good idea to buy used batteries?   
    Oh man do I have a story. Well two...
    When I was about early high-school years, my dad sent me to go fetch the Bobbejaan (for those who don't know, this Afrikaans also means Baboon). My younger sister (probably around 6 at that time) who was inside the house heard this, and came out of the house, waiting anxiously for my return from the storage place, which was around 100 meters away. She was quite upset when I didn't return with the expected Baboon by my side, but instead with a monkey wrench.
    The second was a case that almost turned into labour unrest. My dad and his employees were putting up a water tank. The tank was tied down with a rope, to prevent the wind from doing any bad things. One of the workers untied the rope at one point, and my dad shouted at him (as one does), don't untie that rope you stupid! Well, no, in Afrikaans we call a stupid person a Bobbejaan, so that is what he said, and as many saffers know... that can also be construed as a racial slur. The worker replied "Ek is nie Bojaan nie!", and then proceeded to sulk for the rest of the afternoon. Count your words as they say!
  13. Like
    ___ reacted to PeterP in Cost of solar generation   
    Current SA EV prices are ludicrous - we got ours 2nd hand for R193K with 35K on clock - so then it's ok. Future EV pricing will be in line with ICE in a few years. We had to replace the other car anyway, so for us it made sense.
  14. Like
    ___ got a reaction from Chris Hobson in Housing Victron shunt? And where to put in circuit   
    I'll tell you why you'd normally want it as close to the battery as possible, and then I will tell you why in your case it probably doesn't matter.
    In many systems the BMV serves as a voltage measurement service. It is closest to the battery, so it has the best idea of the voltage. Other devices might be measuring higher or lower because of voltage drops on the cable. Now the BMV has this red fused cable going directly to the positive of the battery, and there is going to be almost no voltage drop on that cable, so on the positive side you are covered. On the negative side, however, it reads the voltage at the shunt, so you should put the shunt as close as possible to the battery. In most cases that is.
    However... putting it slightly further down does not affect its capability to do its job (managing the SOC), and you already have another even better source of the voltage (the BMS itself, if you can read it that is). For this reason it is not going to matter if you put it on the other end of the cable.
  15. Like
    ___ got a reaction from Gnome in Axpert software   
    Open source merely means the source code is available. It does not necessarily mean you are not paid to write or maintain it. Paid open-source work does exist, and because of the enormous effort involved in maintaining it, lots of people are happy to pay the original guy to continue doing it.
    The upside of open source is that I'm not locked into a single provider.
    Of course I am nitpicking, you are not wrong in pointing out that the majority of open source is written because someone scratched an itch, and then released it under some very permissive license because he honestly doesn't care (except maybe to get some recognition, or to not get sued if some idiot uses his code in a medical device).
    What I am getting at here is the usual distinction between the two meanings of Free: Free as in beer, or Free as in freedom. Most Open source projects are both, but what really makes it good is the latter.
    I'm partly in agreement there. The value of a product is not what it took to make it. The value of a product is how much someone else is willing to pay for it. In that sense, this product is selling for the right price, and given the fact that no serious competition has shown up, clearly the price does not annoy anyone enough to disrupt the market and make their own (and give it away for free, as in beer). But conversely, I get annoyed when relatively simple solutions are sold, resold, and resold again, multiplying the income beyond any reasonable original input cost.
    Of course I think the free market principle is more important than my own annoyance, so the market can simply vote with their feet as far as I am concerned 🙂
  16. Like
    ___ got a reaction from jykenmynie in What do you think of these from Takealot   
    Müller was a bit like a furniture store back in the 1900s in Cape Town. If my google-fu has not left me, the remains of that company is still around via Allen and Fisher pianos, who still have premises in Wynberg today. They imported pianos from Germany and sold them under their "house brand". That is why many of these pianos are basically either an Otto Bach or a Carl/Carol Otto under the skin. Some of them are quite good. Others (like mine) look the part but are basically workhorses underneath. After buying such a piano without doing any of the required research (and almost ending up with a dud, but we saved it), I did the work afterwards. That's when you discover how the styling changed over the years. Simply things like "stalactites" (pretty hanging wood carvings under the keyboard) died out in the early 1900s, so if you see that, you know it is very old. Until the 1930s, you usually didn't have legs under the keyboard. Fluting (you'll have to look that up I think) was common from 1900 to around 1925. Overdamper (where the damper is above the hammer) was more common in the late 1800s, but by 1910 pretty much everyone is making underdamper pianos. And so on and so forth...
    The you get to the interesting time when better materials get into it. Using an aluminium rail in the action (the action is the part with the hammers) was a significant improvement from what came before.
    Of course things also went the other way. Good pianos have a Sound board made of spruce. Cheap ones... use a cheaper wood, but then they laminate it with spruce to make it look good... 🙂
    So... yeah there was this story about a guy who went to a fight and then a hockey game broke out... well, we started with batteries, and then I went completely OT. I hope everyone had a good read 🙂
     
  17. Haha
    ___ got a reaction from Louisvdw in What do you think of these from Takealot   
    I mentioned that there are over 1000 different "brands" of pianos, the analogy is that it is the same for batteries 🙂
  18. Thanks
    ___ got a reaction from Deon in ZA in What do you think of these from Takealot   
    Müller was a bit like a furniture store back in the 1900s in Cape Town. If my google-fu has not left me, the remains of that company is still around via Allen and Fisher pianos, who still have premises in Wynberg today. They imported pianos from Germany and sold them under their "house brand". That is why many of these pianos are basically either an Otto Bach or a Carl/Carol Otto under the skin. Some of them are quite good. Others (like mine) look the part but are basically workhorses underneath. After buying such a piano without doing any of the required research (and almost ending up with a dud, but we saved it), I did the work afterwards. That's when you discover how the styling changed over the years. Simply things like "stalactites" (pretty hanging wood carvings under the keyboard) died out in the early 1900s, so if you see that, you know it is very old. Until the 1930s, you usually didn't have legs under the keyboard. Fluting (you'll have to look that up I think) was common from 1900 to around 1925. Overdamper (where the damper is above the hammer) was more common in the late 1800s, but by 1910 pretty much everyone is making underdamper pianos. And so on and so forth...
    The you get to the interesting time when better materials get into it. Using an aluminium rail in the action (the action is the part with the hammers) was a significant improvement from what came before.
    Of course things also went the other way. Good pianos have a Sound board made of spruce. Cheap ones... use a cheaper wood, but then they laminate it with spruce to make it look good... 🙂
    So... yeah there was this story about a guy who went to a fight and then a hockey game broke out... well, we started with batteries, and then I went completely OT. I hope everyone had a good read 🙂
     
  19. Haha
    ___ reacted to introverter in What do you think of these from Takealot   
    Road trip!

     
    Best I can do to almost head back on topic...
  20. Like
    ___ got a reaction from Rclegg in What do you think of these from Takealot   
    Osaka batteries are from Pakistan. But that is if you assume this is actually an official Osaka battery. It is quite common for Chinese companies to slap a name on a product to make it sound cool. Many many German sounding pianos (another passion of mine) are made in China. They will spend money to buy the brand name, so some companies actually make money by allowing Chinese companies to use their brand. Telefunken? China. Philips? China.
    So I think we can safely assume we don't know where that battery is from. You can probably expect around 700 cycles to 50%.
  21. Haha
    ___ reacted to introverter in What do you think of these from Takealot   
    the difference between the german sounding pianos and the wannabes being that anything played in the key of G having a slightly guttural quality to it... 😉
  22. Like
    ___ got a reaction from introverter in VE.Bus Smart dongle Temperature?   
    OK, this was another bug fixed in Venus 2.60. I patched it in place. Try it now.
  23. Like
    ___ reacted to phil.g00 in Are Vertical Axis Wind Generator worth it?   
    You cannot exceed the voltage rating of the MPPT, this is a hard limit. In your case I believe 4 panels in series will be the maximum length of string. 
    Exceeding this voltage will damage the MPPT.
    The number of strings is  a different story, this is the current output limit superimposed on you by the MPPT.
    It is not a strictly a power limit but depends on your battery voltage. It might be known as a 48V system, but the charging voltage may be 10V higher. It is a current limit, in your case it is 100A.
    If you added another North-facing string that peaked simultaneously with you existing panels you would experience "clipping". In other words you'd hit your ceiling output and the peak would be a flat line. Exceeding this limit shouldn't damage anything.
    Indeed it may be worthwhile having a number of strings so that most of the year you don't clip, and only clip on great days.
    I am a proponent of not having North-facing panels, and rather having E/W panels. This way I can get a lot more panels for the same noon peak. More panels are better when it is overcast.
  24. Like
    ___ reacted to DeepBass9 in Are Vertical Axis Wind Generator worth it?   
    Just check if you have enough wind. There is no power to be harvested in a breeze, you need strong wind. Also in strong winds, wind generators can be noisy and your neighbours might not like it.
  25. Like
    ___ reacted to phil.g00 in Are Vertical Axis Wind Generator worth it?   
    Some reviews here: https://ie.trustpilot.com/review/tesup.co.uk
    Hugh Piggott of Scoraigwind literally wrote the book on small wind. I would not discount his views out of hand.
    He thinks VAWT are toys. 
    However, even with a great turbine you need wind, if you don't live in a really windy place you don't have it.
    If you add vertical E-W panels, you can produce watts earlier and later in the day using the same charge controller. They wont produce energy at night, but it is still at a time when your present set up isn't generating.
    Maybe not a lot more watts, but I'd wager many times more than that VAWT in a year.
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