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Gerald_D

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Everything posted by Gerald_D

  1. The most ridiculous part of the design is having 2 fans side-by-side and only running one at a time. With a 1kW load, the small fan runs continuously, the big one is idle. Testing with piece of thin paper it can be seen that most of the inlet air is coming from the idle fan, not from the top inlets. Thus the heatsinks are bypassed. On top of that, some of the warm air coming out the small fan goes back into the idle big fan. When Utility is charging the battery, only the big fan runs, sucking a lot of its air in through the idle small fan. At a 2.4kW load, both fans are running. I am happier to run the inverter at 2.4KW rather than 1kW. I am trying to think of a discreet fix to get both fans to run together, but mechanical engineering is my field, not electronics. Any suggestions?
  2. I am new to Axpert (clone), but not new to inverters and chargers in general. Yesterday I connected a Must PV1800 3kW 24V and had a chance to observe this thing in action. There are 2 fans at the bottom, big one and small one - they blow air out, downwards. The air inlets, both sides of case are near the top - 290 punched holes, each 3mm diameter. The internal heatsinks are oriented for vertical airflow. 1. Natural convection on a wall mounted system is upwards - the fans fight this and pull air downwards. Why not make the fans suck in at the bottom and blow out the top? 2. the 290 punched holes have less cross-section area than the fans - they are a restriction. Needs more or bigger holes. (small holes have edge throttling effects on their sharp corners too) 3. Both fans do not run together. Often they run independently. When only one fan runs, the easiest inflow of air is through the fan that is not running - this air bypasses the heatsinks! Once this thing is out of warranty I will force both fans to run together (and increase the intake at the top). Probably also turn the fans over and reverse the airflow to go upwards. Might get away with then reducing the fan speeds and the noise. 4. The wiring connections are high off the wall and right next to the fan - how does one do a neat trunked installation without obstructing the airflow? Okay I am just blowing off steam after a frustrating day, sorry. (another ridiculous asian thermal design is the very popular DALY BMS for lithium batteries - two fake plastic fans on top acting as a blanket on the aluminium case!)
  3. I found the problem - not finger trouble The inverter reads the battery voltage 0.3 to 0.4V higher than what all my voltmeters and the smart BMS reports. I had set float voltage to 27.0V and the battery voltage was 26.8. However the inverter was throttling the current back. For a test, I set float same as bulk at 28V and then 28 Amps was measured going to the battery. I don't know if it is worthwhile taking the inverter back because of this error - I can just offset the settings by 0.35V. The other problem of charging not starting while under load with utility supply, is my impatience. It takes about 30 seconds for the charger to come in under these conditions.
  4. Hi I am getting stumped by a Must inverter PV18-3024VPK (3kW 24V). It works fine as a UPS, but: - after a loadshed event, my load switches nicely back to utility supply and the display shows the battery being recharged. But my ammeter tells me the battery is not being charged. If I switch off the load, then the charging begins. And the charging will continue if load is switched on and off after that. Weird - the utility AC charger can be set either 20 or 30 Amp, but irrespective of the setting, my ammeter shows a very exact 10 Amp only. It is the first time that I have tried a setup on Axpert / Must / clones, so I am hoping it is only finger problems from my side. Hopefully a forum member can give some hints. Alternatively is there somebody in the Cape Town area that I can pay to do the setup? The whole system is still portable in the back of car. Thank you (The user manual is attached - all settings been put back to default for now) User-Manual-PV18-3-5KW-VHM-off-grid-MPPT.pdf
  5. In the post above I showed MajorTech's Veti modules, but I much prefer Onesto's Matrix or LeGrand's Ysalis ranges. Modules make a very neat installation. I can think of nothing worse than power trollies and extension cords!
  6. I hear you. At some plug outlets I pulled a second twin+earth through the conduit to feed dedicated UPS modules. See pic, some modules will be blue colour, on the UPS. Feeding a 1.5mm2, and making all the extra module connections in the 4x4 wall box was easier that way. Remember that the whole UPS circuit is behind a 15 Amp breaker near the Victron. (Not at home now, so I stole a pic off the net - I sometimes have the modules on the left as blue UPS) My biggest loads are the fridges, and the cabtyre supplied with them is only 1.0mm2
  7. Some more detail about installation; links for Inverter spec sheet and Watt meter Comments re Victron; When loadshedding ends, the Victron takes about 5-10 seconds to decide that Eskom is really back and only then switches Eskom power back on. It does this seamlessly and I suspect it may be syncing with Eskom before it switches. This delay is great because it is known for the Eskom network to be shaky when it returns and that some home appliances don't like this shaky period. However, when Eskom fails, there is a tiny glitch when the Victron kicks in. Supposedly 20milliseconds and it is only visible on fluorescent lights, nothing else. The Victron is the most silent brand that I have used for this application (have assembled 11 similar systems for friends and family). Hum noises of all systems were minor, but the fans were of varying design and noise level. Noisiest was Meanwell TS1500 where the fan runs even under no load when the temp is over 25C. The Cotek S1500 was rather good with low-noise fans coming on only when they really had to. WRND has very noisy fans coming on above 500W irrespective of temp. I have very seldom noticed the Victron fan running, and then only at a low level. Victron does not have a power outlet socket like most of the other brands. Actually a good thing because the other brands force you to buy Schuko or British plug connectors. Victron allows/requires cabtyre connections for input and output and that is why I have a standard plug outlet behind the Watt meter. This Victron's battery charge side is the best I have yet seen in a UPS. Dear old Eskom forces 2 requirements on us; a. quick battery recharge times when loadsheds are close together and b. months of battery storage/maintenance when there are no loadsheds. The Victron handles both these requirements very well. The charge current is very high - so high that most customers probably want it limited to a lesser value. The Multiplus 1600 can charge 70 Amp at 12V, ideal for 4off 105 A.hr batteries. My system mostly has 3 batteries and only 2 batteries when I go camping, so I have had the charge current limited to 60 Amps (30% of battery C value). Then for the storage times, it effectively has a 4 stage charger - after floating the batteries at 13.8V and detecting no load for 48 hours, the float voltage drops to 13.2V for a week (after which it does a full charge cycle again). These numbers are all adjustable with a laptop/software/special cable. From the Victron's spec sheet it can be seen that it will drain a 12V battery system down to 9.5V before it cuts out. This is considered to be too deep down for common lead acid batteries where the generally accepted number is 10.5V. Again, this number can be adjusted with a laptop/software/special cable. Be wary of buying a Victron at factory default settings and then connecting a couple simple lead acid batteries. . . . . they will be force fed at 70 Amp and drained down to 9.5 volt.
  8. By January 2008 we realised that we are in for serious loadshedding in the long term. I then knocked together a little UPS with a 1500Watt pure sine wave inverter, charger and two 105A.hr batteries. That was before LED lights and batteries in garage door openers and gates. It served us very well until 2012 when we built a new house and wired it for having a UPS. Essentially we have 2meters of cabtyre coming out of the wall in the garage with a blue standard 3pin plug top (like the plug end of an extension cord). This is connected to all the consumers needing UPS during loadshedding. The plug can go into a generator, an inverter or into a nearby standard outlet point. But we typically have an inverter/charger system between the blue plug and the wall outlet. If in the rare case that the inverter may smoke, the blue plug goes straight into the wall. Because we are talking of loads well under 3000 watt, the blue plug and wiring through the house is 1.5mm2. Today we have a Victron MultiPlus 1600VA installed as the inverter. 12V with 3off 105 Amp.hr batteries. (Why only 12V? Because sometimes a battery is taken out for camping and the home system keeps going on 2 batteries.) The biggest consumers are 2 Bosch fridges, 9 fluorescent lights that really should have been changed to LED by now, and 3 ceiling fans connected into the light circuits. A desktop computer, inkjet printer, 2x modern flat TVs, router/modem, 2x MiBoxes, soundbar, all lights in house (LED), burglar alarm, outdoor beams (another reason for 12V), gate and garage door motors, sewing machine, cell phone chargers, bedside clock/alarm, outdoor braai rotisserie motor and lights, mosquito repel devices. This is a long list of consumers, but only a small amount of them run at the same time. The obvious stuff that's not on the UPS circuit are microwave, oven (we have a gas hob, no plug outlets above counters in kitchen and scullery, pumps, air con, towel rail or ceiling heater in bathroom, plug outlets where heaters, vacuum cleaner, hair dryers may get plugged in. Have never had the Victron trip or even give an alarm. Using an energy meter, our consumption at the blue plug is 210 Watts for most of the day, rising to 700 Watts in the evening. The peak hold function of the watt meter shows 1200 Watt over a week, but the sampling rate of the Watt meter is unknown. If the fridges are taken off the UPS circuit, the peak during a week is 800 Watt. I can thus highly recommend the Victron MultiPlus 1600VA for this application. It really is a simple DIY job - the most work being the wiring of the consumers back to the UPS. However, a word of caution; the Victron must be set up (via special cable, software and laptop) to work correctly with your battery choice - check that the seller is happy to do this for you.
  9. Here are the Watt ratings as opposed to the VA ratings of those Mecer inverters: https://mecer.co.za/ivr-1200lbks-12v-power-inverter/ 1200VA model is 720W and the 2400VAmodel is 1440W
  10. A few seconds is optimistic - my Meanwell TS 1500 inverter says it can handle twice the continuous power for 30 cycles (0.6sec) and that is one of the better brands. See: https://www.meanwell.com/Upload/PDF/TS-1500/TS-1500-SPEC.PDF
  11. Your Mecer's VA ratings (1200 and 2400) may be the so-called "peak" power ratings. Their continuous power output ratings could be only half of that. I used to run those Coromasters off a Cotek S1500 (1500VA continuous, 3000VA peak) pure sine wave inverter. I suspect the Mecer 2400VA will do the job, with a bit more noise than usual. Those Mecers are not the best things for running motors.
  12. Have started noticing that Victron drops the float voltage down to 13.2Volt if the batteries have not been used for 48 hours and then applies a full charging cycle every week. I am thinking to emulate this by turning my 13.7V float charger off for most of the time. Floating above 13.5V for long periods makes my batteries weep and it obviously dries them out.
  13. All the new Victron chargers float at 13.2 Volt but then have a full 3 stage recharge once a week. Some people cannot afford Victron . . . . . We can get 20Amp 3-stage chargers at about the R500 mark. But they float at 13.8 Volt which is too high for my liking. I see sealed batteries weeping after a few months of no loadshedding. Taking a cue from Victron, can I put those cheap chargers on a geyser timer so that they only get about 3 hours of mains power once a week? The connected charger has a parasitic draw of 70 milliamp; about 11 Amp.hr. The battery size is between 100 and 200 Amp.hr. Of course, when we have loadshed season, the timer will be bypassed and the charger will do its normal thing. I am thinking of this for the many months we often have without loadshedding . . . . just to maintain the batteries with a weekly charge. Thanks for considering
  14. Since I started putting together systems in 2008 to beat the loadshedding problem, I made the assumption that Eskom would be available more often than sunshine. Charging batteries with Eskom makes more sense to me than using solar. Loadshedding would have to get a heck of a lot worse before Eskom is unreliable for charging batteries. My new house's roof is designed for solar, but I don't think that I would be using it in my lifetime.
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