Modina

I can understand why you want to run an "alternator" from mechanical input power such as a diesel or petrol engine, a water wheel, or something similar, but why run from a 230VAC motor? Why not use the 230VAC as is? Is this only a test setup to later replace the AC motor with an ICE-engine? The only potential problem I see is that single phase rectification would produce a fair amount of ripple, even with a 15000uF cap. 3-phase alternator would produce much less ripple. A solar panel can be modelled as an ideal voltage source with a series output impedance. For instance, a particular Canadian Solar 360W panel might have Vmp=39.6V, Imp=9.10A and Voc=47.0V Thus, output impedance Zo = delta_V / delta_I = (47.0-39.6) / 9.1 = 0.81 ohms If you where to connect X panels in series, you would obviously increase the Zo by a factor X. Modelling your 3-phase alternator/ bridge rectified and smoothing cap would be a bit more difficult. As a 1st order estimate you could assume that it is only the capacitor's ESR which you could look up on a datasheet of that specific capacitor you use. There are a few different MPPT algorithms used and I really don't know much about these. I would hope and presume that AC ripple on the input is too high a frequency for the MPPT to react on, otherwise the MPT could become unstable with weird side-effects. I would be a bit concerned of overloading your 550W drive motor. A MPPT is supposed to adjust to your input power source, but this depends on the correct source impedance. With a real solar panel, that is a given, but in your setup, the smoothing cap changes the source impedance. If you make the series resistor too small, you will overload the motor. If you make the resistor too big, you will loose a lot of power as heat dissipation and limit the already lowish 550W power source. @Scorp007 suggestion of starting with a 10 ohm resistor sounds about right. Best would be to use a wire-wound rheostat with a sliding contact that is adjustable. Monitor the input power to your motor and then slowly reduce the resistor until your motor runs at close to maximum power. As you only have 550W peak input power, your MPPT should be able to handle it without problems. BTW, a 15000uF 400V or higher capacitor... I think will require a wheelbarrow to cart around. Not to mention your servo motor. If you sell that heavy machinery you should get enough money to buy a 230VAC high power battery charger.. 😆

What is the setting menu number? @Coulomb said it's not a problem. Seems that the Battery DC/DC step-up converter is fully isolated. So you should be fine using a normal (un-isolated) buck regulator. LAN (ethernet) uses small isolation transformers. They are always contained in one of these small black blocks close to the RJ45 connector. Obviously they can't withstand hundreds of volts of isolation. I don't know what they are specced at, my guess is that they should withstand at least 100V. Battery voltages should not be an issue.

I agree with @Bobster. I think using the gennie is likely to be problematic. There are 4 possible solutions. All problematic in one way or the other: 1. Mechanically - Modify your generator to have a very large flywheel. Any load variation will be dampened and the AVR and governor will have enough time to keep the speed and voltage within acceptable norms. 2. Electronically - Replace the genie with a so-called inverter generator. Simplistically you can see that as a conventional generator with an AC/AC inverter. These generators are expensive. 3. Electronically - get yourself a 230VAC battery charger that is rated for 2KW or thereabouts. For example, there is a 48V 100A EG4 "Chargeverter". These are also very expensive and will cost as much as a smaller inverter. 4. Electrically - If you don't have solar panels you could possibly use the MPPT input. I am not familiar with the specifications of the Luxpower so you would first need to check the maximum MPPT input voltage. In theory, you could rectify the genie AC to DC and then fit an electrolytic smoothing capacitor to create a 320VDC voltage. However, MPPTs seem to be very temperamental regarding their input as well. SunSynk apparently recommends connecting a 1 or 2KW "resistor" in series to simulate a power source that looks more like the output of solar panels. Also, 320VDC is more dangerous than 230VAC and one would need to look carefully at the various parameters of source impedance, power, voltage, input current, etc. It would also be hugely wasteful in power. That 1 KW resistor would act like a heater. This might be the cheapest solution, but I would not recommend it.

I grew up in the Cape and then lived my working life in Pretoria. The Cape has changed drastically over the last 15 or so years, for the worse. These days the electric fences and walls are as high as in GP. And yes, Pretoria has much nicer weather. Just glad to be rid of lightening. They used to say it only rains twice a week here. First for 3 days and then for 4. Property prices & sizes are an absolute nightmare. However, service delivery is like day and night. I can renew my car licence in under 5 minutes. Municipality workers are super friendly and things normally get fixed within one or two days of reporting it. Fault reporting is done electronically.

How do you get to the sense mode? I don't know of such a function or setting on Axperts. I only know of Victron inverters that have a low power mode where they pulse the 50Hz at a 1/50 duty cycle and then measure the current. If the current is over a certain threshold the inverter activates normal power mode. I presume you use a 12V buck regulator connected straight to the 24V battery for your 12V DC loads? I think you should use an isolated step-down regulator if you do that. If one of your 12VDC loads inadvertently is connected to an earthed system, such as a mains powered PC, TV, HiFi, etc., the earth could find a path to the negative battery terminal. As far as I know that is not permitted and could damage the HV DC/DC or one of the other converters.

Victron can be considered the Mercedes of domestic inverters, but like a real Mercedes, there are pros and cons. Here are a few things you should know: 1. Victron uses different modules to make a system. So you need more "stuff". More wires, connectors, etc. This also needs more time to install. Other systems normally are single-box solutions. Your installation could look more like a mad scientist experiment than with other inverters. 😆 2. Victron inverters are referred to as low frequency inverters. They use 50Hz toroidal output transformers (usually 2 of them) to do the low-to-high voltage step-up. Most other inverters are "transformerless" designs. Toroidal transformers are big and HEAVY. They are also rather expensive, especially if we talk of a few KW. They give a totally galvanically isolated output which has advantages over the normal inverters that have some DC HV bus connected to the AC output. Now, toroidal transformers are very efficient but they DO have losses. I expect about 3%. This loss needs to be added to the H-bridge switching losses that all inverters, including Victron, use. So I think that a Victron might have slightly less efficiency. Oddly enough, the no power idle current on Victron inverters is normally better than other designs. Victron also has sleep/ power saving modes which other inverters don't have, but I am pretty sure that no Powerforum member would be interested in these modes anyway. 3. Victron make a lot of IP65 rated products. This has historic reasons due to their origin in the boating/yachting sector. This means they are 100% water proof. It also means they are throw-away products. They cannot be repaired. The electronics are cast in resin or rubber compound. The Multipus itself can be opened and repaired. The MPPT on your list, as far as I know, is potted in rubber. So the MPPT is not serviceable. (Go to Youtube and search for Victron MPPT repair and you find a lot of angry people with hacksaws and angle grinders trying to literally only replace a blown fuse.) 4. Victron only keeps spares for 10 years. Now, I don't have too much of a problem with that per-se, if they would repair down to component level. I know someone with an old inverter which is considered unrepairable because they cannot source the three PCBs used on that device. THIS I consider a very, very poor show. Sometimes, when things go wrong, PCB tracks can get burned and that would require a completely new PCB for a reliable repair. But mostly, individual components can be replaced. Either they can't or won't do that - so it seems. I refer to a specific case I know of in Cape Town. Perhaps they have some brighter techies up north. Who knows. 5. Victron normally has no, or very minimalistic user I/O control panels/displays and relies on doing everything via Bluetooth or WiFi. People like it. I personally don't. I think we already have too many devices in our homes that radiate EMF. But hey, I am a nut case when it comes to that. So you can scratch out this point. So if you have the money, go buy yourself some blue bricks. 😀

Yes the small converter you would need to solder. The larger one has screw down terminal blocks. Should you get the bigger module and you want to set the output current then do this: Switch your multimeter to the highest DC current measuring scale, normally 10A, and then connect the meter across the output. This will short circuit the output, but this is fine. The regulator will force a short circuit current to flow through your meter. Adjust the "CC" potentiometer to the current you want. Depending on the multimeter used, the meter scale and the required current, you might then want to select a lower Ampere range, so as to measure the current with a better resolution. This should obviously only be done on regulators that have CC (constant current) adjustment capability. To do the constant current adjustment you need a suitable power supply. You could simply use a 12V 7Ah SLA battery connected to the INPUT, to feed the circuit. Because the short circuit current is at zero volts, the current drain on your battery will likely be less than 300mA.

For charging, the cheapest hardware (R70) would be a small buck/boost regulator like this: https://www.communica.co.za/products/hkd-dc-dc-buck-boost-1-25-35v-4a?variant=44293669519660 You would need to place this into your own small enclosure and you would need a multimeter to adjust the pre-set potentiometer to give you an output of 13.85V to float charge a 7Ah SLA battery. An even better module would be this R340 buck/boost regulator: https://www.communica.co.za/products/dgm-buck-boost-solar-1-30vdc-10a?variant=19665729519689 The advantage with the more expensive regulator is that you can adjust the output current limit. With this you could charge small lithium batteries as well. Both regulators can boost the voltage, so you could even charge 6V and small 24V batteries. They are both switching regulators so you can expect about 85-90% typical efficiency, which would be much better than a PWM charger.

1. Can it be safely assumed that all inverters will have their comms port 100% galvanically isolated? 2. Is the +Vcc on the RS232 connector always +5V? I was very surprised to find my cheap 24V Axpert "shouts" at +12V/-12V RS232 logic levels. I haven't seen equipment in years sticking to the original RS232 specification. Ever since the MAX232 was launched, nobody respected the old standard. Today many use +5V/-5V logic levels. What about battery BMSs? I get the feeling that some battery manufacturers possibly galvanically isolate their comms while other rely solely on the inverter?

For solar power, one would assume that a MPPT is always a buck converter. But this is not so. The low voltage MPPT Axperts apparently use a buck converter and the high voltage MPPT Axperts use a boost converter. What SunSynk inverters use, I have no idea. For wind turbines and some other applications one would also expect a boost converter. All components, input and output, will have maximum current, voltage and SOA (safe operating area) power limits. This is true for any type of power supply. Irrespective of the topology used, if you throttle the output power you will reduce the input power and also the input current. Conversion losses within the MPPT can be factored into the control loop. I can't see why the current control loop would/could be imperfect. A MPPT should have all currents directly or indirectly under it's control and can thus self-regulate. The only parameter it cannot control is the input voltage and that is why it is so critically important to stay within the maximum input voltage. If input current is really so critical, the manufacturer should at least specify more than one value, like they do with the MPPT's input voltage range.

Steve, 1000%. I could not agree more. From a technical point of view, I simply cannot understand this current limit on the input side of an MPPT. Only the output side of an MPPT should be current specified and limited. The MPPT should perform it's own output current limiting, but the specifications should alert the end-user, or at least the installer, about said limit. Otherwise people will place too large panels at the input side and never reap the benefit. MPPTs need a blocking device, normally a MOSFET, to disconnect the panels when they stop production. This is to prevent back-flow into the panels. But this is still no reason for such a specification. At the end, it is the firmware that determines the maximum output current and the back-flow control MOSFET just needs to be specified to handle the "geared" (input-translated) current. The firmware will always know input and output voltages and currents. Some MPPTs do not measure the actual output current, but can infer it from the input current and voltage data. At the end of the day, I see the MPPT as a fancy, self-regulating impedance transformer with intelligent over current protection. To me, the way they spec MPPTs just doesn't make sense. Perhaps these inverters make use of a different topology to what I have seen in stand-alone MPPT designs. Or I am simply too stupid to understand it.

You can connect it whichever way you want and it will work. I even said that the right way might be more problematic than the left diagram, depending on less-than-ideal cable lengths. I also realise that theory is one thing and practise might be a very, very different thing. Meaning, it is not always practical, and sometimes not even possible, to make the setup as dictated by science. I really think that a few millivolt difference between batteries are nothing to worry about. It is good to understand the basic science of it and try to implement it as close to ideal as is practically and in a way that also doesn't break the bank. These cables are not exactly cheap. If I have a less-ideal system and someone told me to change it and spend R1000 for a few mV, I would tell him to take a hike. BTW, I know very little about parallel inverter operation. "Nothing" would perhaps be the more accurate word. I think that connecting PV to multiple inverters' MPPTs in parallel would be a terrible idea. Two separate MPPTs would likely fight with each other. However, paralleled systems "know" of each other so it would be feasible to sort it out in firmware and thus keep the peace. So the question is, can parallel inverters also have their MPPTs paralleled? I am asking this because if the answer is yes, would it not then perhaps be better to give each inverter it's own battery? I realise this would have a drawback on redundancy and maintenance.

Look at the left diagram. The red battery cable from Fuse to Master is shorter than the red cable from Fuse to Slave. That is a problem. They should be equal length. Now I know this is only a diagram, your real world setup could use equal lengths or it could be worse than what is shown in the diagram. Ditto for the black battery cables. Also, the cables from the Master Inverter to the Fuse is longer than those from the Slave inverter to the Fuse. Here it is not quite as important but still sub-optimal. You want both the master and the slave to read the same battery voltage. With different length cables, the longer cables will produce more voltage drop. In the left diagram, the Master will read a lower voltage than the slave. The better way is to connect it as in the right picture. However, even there you should watch out for cable lengths. For instance, make sure that the red and black battery link-cables are of the same length. I would stick my neck out and say that a system with perfectly matching cables in the left, will be BETTER than the right hand diagram if the right hand side is using vastly differing cable lengths. Imagine the current running from the red cable to the battery, through the battery and then back via the black cable. Every cm of length will have a fixed amount of resistance that will drop some voltage. Rule 1 is - have about the same loop-length between similar devices. Rule 2, keep the wires as short as possible. In that order. Only if you have infinite small distances, then it doesn't matter. 😂

Where is the inverter? If I look inside, I only see transformers. 😆

If you charge your battery at 20A you will draw 20A * 25V (nominal) = 500W + a little bit more for some losses. Your 15A plug can supply 15A * 230V = 3450W.

@TaliaB I first thought you meant 5.5KW 😂 I see it's 5.5K Rand. Well, the guys show the right pictures, standing in remote locations with no other houses far & wide in sight. R 5500 sounds very cheap. That price will likely only be the generating head with blades. They say with MPPT, but I doubt it. Although that MPPT is only analogue, no microprocessor in there. I saw the schematic of someone who back-engineered it. It's not 48V, only 12/24V. It even says so on the label. The mast alone, with steel anchor cables, foundation, etc. will likely cost another 5.5K, if not more.

I agree. I have moved from Pretoria to the Cape and have been here for 3.5 years... What wind? Simplistically you get a breeze, wind and a storm. Storm = damage, trees blow over Wind = walk on the beach and get sand blown into your eyes Breeze = having your hair blown deurmekaar.... 😃 I often go to Strand and the times I experienced wind, I can count on one hand. I think wind-turbines are a hobby for the tinkers and DIYers. You need quite an expensive setup to even just get an occasional 300W_ave or 1000W_peak. I don't think it is worth it for someone that has grid available. If you are truly off-grid and stay in a very windy and remote location, then it might make sense. Wind-turbines need a lot of regular inspection and mechanical maintenance or they can be very dangerous. You would not want a thing like that land on your neighbour's property. The properties in the cape are extraordinary small. Even if one had reliable wind, a wind-turbine would be a non-starter for most people. Small wind-turbines that can generate 10 or 15W for things like remote sensors, weather stations, etc. can make sense.

You are talking about lights. Only lights. LEDs are not good from a health perspective (too much blue light radiation) but they are the only lights with a decent efficiency. So LEDs it is. Well, LEDs are by definition low voltage devices, each LED having a forward voltage of typically 3V. So if you are only catering for lights, going the 230VAC inverter routed is a bad idea. There are many reasons for this: 1. An inverter costs money which you could save by staying with low voltage DC. 2. If you are extremely lucky, your inverter will waste 10% of your battery power. For tiny inverters (as in your picture), the losses might be close to 25%. By comparison, a low voltage DC system will have no losses. 3. You would need to remember to switch your inverter off to prevent battery drainage. A low voltage DC system could remain "on" 24/7 without drainage. 4. 230VAC can be dangerous. Especially on small inverters and even inverter trolleys where nobody fits earth leakage protection due to cost considerations. 5. The safety aspect here is even more important. Your system will not be integrated with the building. You will likely have loose wires across floors, etc. Wires over which people could trip, tearing wires out of their connection blocks and exposing the user to potentially dangerous high voltages. 6. Even the best pure sinewave inverters produce HF switching noise. Small modified sinewave inverters will really be noisy as the manufacturer will not use any filter components due to cost considerations. Such noise could cause interference in RF (radio frequency), audio and video systems. The main downside to low voltage DC is that the available form-factors of the LED lamps is limited and that these bulbs are not freely available in your Game, Checkers, etc. Use MR16 12V spot lights that are available in 3, 5 & 6W ratings. Although being DC, these lights will work with any polarity and at a constant brightness with any battery voltage between 11-15V. If you use LED strip lights you need to be careful. These are unregulated and thus require the correct DC polarity and an exact 12V. Voltage fluctuations will cause brightness fluctuations and over-voltage would kill them. For these, a buck/boost regulator would be the best option.

I first wanted to disagree with you, but you do raise an important point. My house still uses steel conduits. In new buildings, conduits often carry bare-copper earth wires. Those earth wires, or the steel conduit, has zero isolation. So if one where to run a 12VDC wire with an isolation of only 200V, at first thought, one would expect to be much better off than that bare earth. However, if that low voltage wire happens to touch/press against a 230VAC (bare) termination at a light switch, wall-socket or similar, then the isolation barrier would not be sufficient. This is a very likely condition that could happen in a real world scenario. So seen from that perspective, all wires should carry sufficient isolation to (single handily) withstand the highest voltage carried within the enclosure. Anyway, it is a moot point for me because I would use normal house wire for the 12VDC circuits. A requirement for ample isolation is a no-brainer, what irritates me about SANS-10142 is their insistence on AC and DC separation.

Yes I am aware of a divider inside trunking being allowed to separate AC and DC. A divider in a 2x4" wallbox is not workable. In a 4x4" maybe. I might need to use two wallboxes or otherwise switch all lights to 12V operation.

Please let us know if/how you can resolve the problem.

I have problems searching on powerforum... I now used an external search. There seem to be more than one thread as the one I found does not include the long discussion we had. I think you should definitely take this up with Luxpower. This seems to be a general complaint with these inverters.

@Scorp007 beat me to it.... We had a similar complaint here about 2 or 3 weeks ago. I don't seem to recall that there was a specific resolution. Your home theatre AV receiver/amp will likely use a conventional mains transformer. Your sub-woofer is a 50/50 chance that it too will use a 50Hz transformer. If not, it will use a switch-mode power supply (SMPS). A SMPS rectifies the AC to DC first and would be happy to work with DC inputs as well. A conventional transformer however, would immediately saturate (magnetically) when presented with a DC voltage. Such a condition would blow the fuse. It is speculated that an inverter might misbehave due to buggy software, whereby the 230VAC output momentarily goes DC at switch over. This would explain why most electronics would work quite happily, as most uses SMPSs. Older equipment, or anything that uses a conventional 50Hz transformer, will possible blow a fuse. A very small transformer such as might be used in an old clock radio might not actually be fused and could possibly get damaged by such an event. I can't remember if the other complaint was also from a Luxpower inverter. To confirm the theory, one would need to check the 230VAC with an oscilloscope and electricians don't normally have access to this equipment .I will try and search for the other thread. If that was also a Luxpower then this becomes very suspicious. If the theory is correct, it should be possible to fix the problem by upgrading the firmware.

No physical layer communication bus such as RS232, RS422, RS485 or CAN has the ability to pass so much current as to burn PCB tracks. A fault like this is just about always as result of ground voltage differences. Whatever communication interface is used, the final transceiver chip(s) should be galvanically isolated using opto-, magneto- or capacitive couplers. I would check for isolation breaches between the iso-ground and main system ground. Besides a physical issue that one might be able to pick up with a visual inspection, a likely candidate for failure is the small isolated DC/DC module which is normally employed. Cable wiring errors will cause a no-comms issue but should not damage anything. Even if there is a TX-to-TX connection, the drivers should have current limiting and not get damaged even when in this fault mode for extended periods. Transceiver chips will get damaged with common or differential mode voltages that go substantially over their 5Vcc supply. Cable wiring problems should never cause such a condition, as all lines should be within the Vcc supply rails. Measure the resistance between iso-ground and system ground. The reading should be into the megaohms. It is possible that some battery manufacturers play it safe and add communication interface isolation to their battery designs while other manufacturers rely solely on the inverter to provide the isolation.

Transformers in wallboxes? No you misunderstood me. I want to implement a 12VDC bus or distribution network that gets fed from a battery charger/battery. In addition to the existing 230VAC lights wiring, I want to add further 12V lights. I would prefer to operated all lights (AC & DC) from one common switch bezel if that is legal. I wanted to run the 12VDC cables down the same conduits as the current mains wires. However, SANS stipulates that AC and DC wires may not run in the same conduit or trunk. So I say, OK, I will provide a separate DC conduit. The question is, is it legal to run DC and AC into one wallbox. I presume it is NOT. From a legal point, the wall-box can be seen as an extension to a conduit or trunk, and will likely be subject to the same rule. A STUPID rule! Electrically speaking there is absolutely nothing wrong with running DC & AC wires in close proximity. Just about all major appliances such as washing machines, electronically controlled fridges, microwaves, etc. have AC/DC wires bundled in long harnesses. So the SANS issue has nothing to do with underlying electrical engineering issues, but rather some soft issue of what I regard as over-bearing governance to protect an idiot from poking around in wiring and possibly getting confused. I think the problem comes in with SANS not differentiating between low voltage and high voltage. (They user the same words with totally different meaning to what I regard as LV & HV). I agree that high DC voltages are potentially more lethal and that HV DC should thus be handled differently. But 12VDC is inherently safe. @Dimi I dislike centralized systems. Normally people have one inverter and all the lights are on the essential circuit. If that inverter fails the whole house is in darkness. I know one can use battery-backed up LED bulbs, etc. But I don't like it. The most critical lights are in the staircase and those lights are small. There are no battery-back-up options for that. There are some other reasons as well, but I have mentioned them in various other dialogs.