Jump to content


Popular Content

Showing content with the highest reputation since 21/05/2018 in all areas

  1. 4 points

    Backup Inverter firmware

    I have a 24 inverter (provided by inverex) model name: Axpert VM 3Kva Plus . it comes with USB port only. I tried to flash new firmware to it but it failed. so I opened it up and found that there is USB to SERIAL board inside inverter I just took it out and replace it with simple com board from another inverter and now I can flash it with out any problem. The reason that some inverters dosent flashes through USB port is the USB to SERIAL board that is restricted to 2400 baud rate so the inverter can communicate to pc monitoring software but cannot be flashed via USB port because flashing is done with 9600 baud rate. so if anyone want to flash inverter firmware and don't have com port on inverter you just have to replace the USB board the with com board from any other inverter and flash the inverter with out any problem. USB to serial board of my inverter is attached
  2. 4 points

    best practice for absence

    Buy Victron Sorry I couldn't resist, I now almost have all my components for my extremely small all Victron system, so consider me a cheerleader
  3. 3 points

    ROI for Home Wind Turbine.

    My gut is telling me I'll be better off building a treadmill, everyone should take a turn even the dogs. Living under my roof? You better make some power.
  4. 3 points
    So very true . Started with 660 KWh/month now using about 40 kWh/ month .We are pensioners and use solar as much as possible . Replaced globes with LEDs and most equipment at least A+ . For me it is not about the money , I know I can't do better than big power stations . But if you life in an area where the substation fuses have to be replaced up 3 times per week ( Can take up to 4 hours ) and you can see the oil leaking out the transformer you wonder how long it will still last . I will pay more and enjoy solar as a hobby . It is nice to know that alarms is always on and no frustration when the power is of .
  5. 3 points
    Okay then... I did the test. It is not completely representative, since my incandescent lamp is connected to the same end of a 10m extension cable (that's pretty much running at its max capacity) as the large heating element (aka kettle), but I thought it remains a good demonstration: A mere 6V, or around 5% in power terms, causes a visible flicker! Of course, when in inverter mode, the flicker is significantly more noticeable. The battery was receiving a healthy charge at the same time (to eliminate some of the voltage sag on that end), but the result was pretty similar: Drops to around 215V for about a second, and a clear dimming of the incandescent lamp. The cell-phone camera does exaggerate the effect a bit too, it isn't quite as bad as it looks, but definitely noticeable. It's not your inverter. My significantly more expensive inverter does the same. My advice would be to find an LED lamp that's less susceptible to this. Should cost less money.
  6. 3 points
    I worked at Tutuka Power Station for a short stint in the mid 80's. In the control room the station manager had two wall clocks with second hands, one driven from the 50Hz grid and the other by a separate accurate source. Part of the station managers responsibility was to co-ordinate (with other stations on the national grid) speeding and slowing of the grid so that the second hands of the two clocks remained in sync.
  7. 3 points

    LiFePo4 Cells 38120

    I've been playing with these batteries from china, Headway 38120 10Ah cells. Yes that means they are 38mm diameter and 120mm long. What drew me to them is cost per watt is less than a 18650 and they have beefy bolted connections. First did a discharge at + - 0.5 C and let the BMS cut out at 2v per cell, i recorded a full charge at + - 0.2C and then recorded another discharge again 0.5C. The idea is to test the capacity as well as the round trip efficiency, the BMS cutoff discharged at the same rate gives me a zero point, any power i put in from zero point and extract again to zero allows me to calculate the round trip efficiency. Here's my results and i have to say i'm super impressed with them, I'm curious to know what you guys think and if you can think of anything i could test further. I think these things can be stuck into just about anything, 93% at these discharge rates ill sommer make a powerwall Charge Rated capacity 10 A Average Current 2.201 A Charge Rating 0.220067883 C Max Charge rating 0.3902745 C Average Voltage 14.053 V Average Power 51.475 W Total applied power 140.713 Wh Total Charged current 10.214 A Discharge Rated capacity 10 A Average Current 5.564609317 A Discharge Rating 0.556460932 C Max Discharge rating 0.5895413 C Average Voltage 12.45113542 V Average Power 71.27238361 W Total Drawn power 130.768265 Wh Total Discharged current 10.47799797 A Round Trip Efficiency 92.93257653 %
  8. 3 points

    Electric Bicycles

    ...just so long as it is a really short program.
  9. 2 points

    Eskom strike tomorrow

    Been notified that they will endeavour to disrupt all the electricity supplies across the country. It will take weeks to resynchronise all the power stations if this happens. If you want peace prepare for war... Africa is not for sissies.
  10. 2 points
    i think very soon the cost per kWh coming out of the batteries will fall substantially below the cost from the grid. The moment this happens all solar systems will have batteries and all the tricks we use at the moment to maximize daytime solar use will be a thing of the past. The only issue will be to optimally size the individual components for the specific application. No more tinkering! It will be boring and a lot of us will have to find a new hobby .
  11. 2 points
    It is a bit like spending most of your day in the kitchen - eventually you'll learn how to use the Snackwich maker.
  12. 2 points
    Well the ROI is still 15%, but it is better than your alternative investment by a margin of 7% (if all goes according to plan) - still sounds bloody marvelous!
  13. 2 points
    Jip. That's me. Inverter being a online inverter, meaning the loads are ALWAYS on batteries, had it's charger blown to smithereens, literally. EDIT: Online saved my / Electricians bacon, for if any other type of UPS, ALL the electronics would have gone to the scrapheap. And there was a LOT of sensitive stuff on them circuits. So keep the inverter neutral FAR FAR (... Galaxy FAR) away from Eskom's neutral. Like on a changeover switch for simple lights, where the electrician did not listen (understand), you better switch live AND neutral, not just live, as they are used to do with just 1 source like say Eskom. Anyone brave enough to share that neutral between Eskom and inverter, will make me lose my no 1 position on the "Do not Do That or Set the Smoke Free!" board.
  14. 2 points

    best practice for absence

    If included in the box is product discount coupons, my dress size I guess is medium
  15. 2 points


    I had the similar issue at one stage and so dropped [29] from 46V to 44v which solved the issue for me, I didn't want to go down to 42V, because if I have a grid failure I don't want my batteries reaching 42V before shut down. It only ever reached 46V for a fraction of a second during inrush currents for high load startup, but was enough to cause the problem.
  16. 2 points

    Axpert 5Kw Switching On Delay

    ...and both will normally arrive at the destination.
  17. 2 points

    Flat Earthers!

    You should have seen the blowout when the burning IVF clinic thought experiment made a come-back recently and lots of people thought it was awesome and new... :-) If you've ever seen the Monty Python "argument clinic" sketch you'll understand. You don't come to the internet to have a good argument. You come here to have an argument :-)
  18. 2 points

    Flat Earthers!

    The best argument I have heard so far against flat earth is that if the earth was flat cats would have already pushed everything off
  19. 2 points

    bmv 702

    Hi George, You will get a number of different opinions here, so you may well finish reading the thread being more confused than when you started I agree with Mark that your bulk voltage (AxMenu 26) should be set to the Max which is 58.4V, however I don't agree with float voltage settings (AxMenu 27) of 54.4V, and here is why; Your batteries have the following manufacturers recommendations (at 25'): Bulk AND Absorb = 2.5x24 = 60V, Float = 2.25x24 = 54V, Equalize = 2.6x24 = 62.4V Firstly you can forget about equalizing, you will never get there. The Bulk/Absorb/Float is what we need to think about. Bulk is the period where you system will raise the bank voltage over time from wherever it landed up overnight to the Bulk setting in Menu26 (58.4V), at this time your bank voltage will continue to charge at Float setting in Menu 27 (54V). This arrangement completely skips the Absorb period recommended by your manufacturer, which is an amount of time where your bank should be held at the Bulk voltage (this is when real work is done by your charger!). Your manual gives an Absorb time calculation as follows; T=0.42 x C/I T = Absorb time C = 20hr rated capacity (or 1288) I = Charging current (recommended 10% - 20% of C20) - I suggest 200 Amps T = 0.42 x 1288 x 200 = 2.7hr (call it 3 hours at 200amps or 40amps/Ax) Given that Bulk charge will take a few hours in the morning, you can comfortably use the rest of the solar day at absorb voltage, and forget about float charging which is more important for standby batteries than cycling batteries. So to summarize - set BOTH Menu 26 and 27 to 58.4V, and then accept the result - which will be acceptable Rolls_Battery_Manual_Flooded.pdf
  20. 2 points

    charging anomaly

    People falling out the window
  21. 2 points

    Solar MD lithium-ion battery

    Yes I can vouch for them. I have installed about 50 or so of their batteries and have not considered another brand as they just work as they should.
  22. 2 points
    There we go. Can of worms successfully reopened
  23. 2 points

    charging anomaly

    Leave it alone. You're BMV is resetting because the conditions are right, and that it only does that above 97% is not a problem I'd be concerned about. Chances are that while grid charging (presumably loads are also running from the grid) conditions are different enough to cause this reset. While charging from PV while also running loads, the battery current will fluctuate up and down, positive and negative. While charging from the grid the battery current does not fluctuate and is always positive, only dropping down as SoC rises. Is it really any surprise that the BMV resets a bit easier under those conditions? :-)
  24. 2 points
  25. 2 points
    That's how batteries are. You can't get them to full voltage without a lot of current, when they need charge. They need that extra charge to make their internal ideal-battery voltage higher. It's nothing to do with Axperts; all chargers will be this way. That's the bulk charging stage; where current is limited by the available charge power, and voltage will slowly rise from a little above resting voltage to the absorb voltage. The bulk stage is also called the CC stage - Constant Current. For lead acid batteries, and to a lesser extent for other chemistries, there is an absorb stage where the battery voltage is kept relatively constant. This absorb state is also called the CV stage - Constant Voltage. Once the battery is deemed to be full, absorb stage is terminated, and float stage is started. This is another constant voltage phase, but the voltage is lower, so that lead acid batteries don't bubble off hydrogen, and lithium batteries don't do bad reactions that reduce life. In this phase, there is very little charging; it's mostly there to replace charge lost by loads. As for when to go to float, since you have setting 32 set to Aut, float should be reached when the battery charge current falls below (total charge current for all paralleled machines) divided by 5. If that figure is less than 5 A per paralleled machine, the threshold becomes 5 A per machine, i.e. 5 A per machine minimum. If you have a single machine and its maximum charge current setting is (5+1) * 5 = 30 A or more, then this should be low enough to trigger the float stage. Otherwise, your current has to fall to 4 A before it will go to float. The current has to be less than this threshold for 30 seconds (some 1,500 measurements) without exception. So if you have fleeting shade, that could ruin that set of measurements, and it has to start again. So it may take several minutes before it manages 30 seconds without one measurement of 6 A or more. Perhaps try AC charging once it's down to 5 A of PV charging (turn off your panels for this test). AC charging doesn't have intermittent shading to cloud the issue, so to speak.