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MPPT Charge controller.


vulgrim

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55 minutes ago, plonkster said:

My little Victron does >97% with a Toroidal transformer. Of course this is a HF design, so it's not as heavy as the older LF designs :-)

Ditto ... and to add insult to injury, my inverter runs at max 10w standby, when quoting from Vipers link re. the Voltronics: " Regarding the 50W consumption ... Still not great but I don't think its that bad for a 4000w inverter charger. Sure its not the super efficient 8w of the Sp-pro ... 50W idle x 24hrs 1.2kw two extra 200w panels should cover it.  "

Really!!! Still don't think ... unacceptable. :D

And starting the AC ... well, it is at night, or on cloudy days, same as most, and, to boot, I only need 24 v 225ah bank for lean and mean is what it is all about with losses and inefficiency comes into play, then the batts are not yet at Eskom prices.

And remember, it only takes one premature replacement of a bank to wipe out all the savings. Been there, done that. ;)

Voltronics are UPS'es on steroids ... not forgetting, quoting again " Check back here in 5 years time. ". So it is just under 5 years and counting.

I believe, as I said, that Voltronics will mature, but they still have a way to go to get to Outback, Victron and the other big boys, probably in price as well. ;)

Ps. I HOPE I have not jinxed you guys ito battery life or Voltronics lasting 10 years plus.

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I love my Victron. But I have to be honest. If the Voltronic was on the market in 2013... I'd probably have one of those in the garage right now. It doesn't take a genius to realise these things are ridiculously good value for money (but, as I always say, only because they cost so little money). I'm an engineer at heart. I understand bang for buck and making compromises. But I also understand when I see something that was done properly... and so, within all that honesty, I'm still glad I went with the Victron :-)

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Just now, plonkster said:

I love my Victron. But I have to be honest. If the Voltronic was on the market in 2013... I'd probably have one of those in the garage right now. It doesn't take a genius to realise these things are ridiculously good value for money (but, as I always say, only because they cost so little money). I'm an engineer at heart. I understand bang for buck and making compromises. But I also understand when I see something that was done properly... and so, within all that honesty, I'm still glad I went with the Victron :-)

Agreed.

But now I am waiting for you to get your hands on a broken Voltronic device, and the strip it. 

Your feedback MAY make me lean over, but if you get one yourself, after taking it apart, that will convince me. :D

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8 hours ago, plonkster said:

How then do you step up voltages? Sure, you can use some other kind of inductor... but that's cheating. The basic tech is the same. As I understand it, transformerless inverters start with a high DC voltage and chops it into AC.

Transformers are one of the few components that can actually approach 99% efficiency. My little Victron does >97% with a Toroidal transformer. Of course this is a HF design, so it's not as heavy as the older LF designs :-)

http://gareth-watkins.co.nz/transformer-power-inverters-vs-transformerless-power-inverters/ ;)

https://www.civicsolar.com/resource/transformerless-inverters-solar-pv

Edited by viper_za
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7 hours ago, The Terrible Triplett said:

Ditto ... and to add insult to injury, my inverter runs at max 10w standby, when quoting from Vipers link re. the Voltronics: " Regarding the 50W consumption ... Still not great but I don't think its that bad for a 4000w inverter charger. Sure its not the super efficient 8w of the Sp-pro ... 50W idle x 24hrs 1.2kw two extra 200w panels should cover it.  "

Really!!! Still don't think ... unacceptable. :D

Im running 25w max on mine in bypassmode not even standby, standby is claimed at 2w but I have never tested that even :P

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57 minutes ago, viper_za said:

Yea, I googled into those too. Rather vague on how these things work. Friend of mine has an SMA like the one in the second link. Input voltage is a nice 380V! Question remains, how do you take 48V up to 230V witha transformerless design? I'm not saying it isn't possible, I just don't know that it is... :-) All fine and dandy for GTIs, not so much for off-grid and backup inverters.

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3 minutes ago, plonkster said:

Yea, I googled into those too. Rather vague on how these things work. Friend of mine has an SMA like the one in the second link. Input voltage is a nice 380V! Question remains, how do you take 48V up to 230V witha transformerless design? I'm not saying it isn't possible, I just don't know that it is... :-) All fine and dandy for GTIs, not so much for off-grid and backup inverters.

I believe it's time for you to do some research in this as Victron is basically the only one left using the traditional transformer design :P

PS share your findings maybe in a new toppic

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Here's my 2c, having worked with both Victron and Axperts, but I didn't open either of them. I'm sure you can get plenty pics on the net of both inverter's intestines. 

The Victrons are very nice to work with and have a lot of fine tuning, which I wish the Axperts had as well - like being able to set the absorption charge rate and time, something the Axpert can't do. 

The Axpert on the other hand has a nice user interface and makes it much easier to understand what's going on. The fact that the it is ^semi^ hybrid is a bonus since you have less equipment and wiring on the walls, but it could also be a negative point since if the MPPT charger packs up, you have to replace the whole unit. 

IMO, the Victron's can be misconfigured a bit easier if you don't read the manual through a couple times and don't understand how to work with the jumpers.

At the end of the day it all really boils down to the software on the machines which determine how they work and what they do. At a component level 

The Axpert's AC wiring terminals sit at an akward angle whereas the Victron's is a bit easier to work with. 

What I do miss on the Axpert inverters, are isolators. And, the axperts need a surge protector before, and after the inverter, they don't have as much built-in self-protection as the Victron's. I had to RMA one in November and now two again, for two different clients.

 

I have worked with Vicrton, Microcare, Axpert, Powerstar and Infinisolar, and have to say that each one has it's own good points and bad points. Axperts are cheap, very cheap in comparison to the others but I do think it's a good product. 

 

P.S. Microcare also still use transformers in their inverters.

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2 hours ago, viper_za said:

I believe it's time for you to do some research in this as Victron is basically the only one left using the traditional transformer design :P

Fine, I'll take your word for it. I'm not offended that my Victron is "old design"... don't care really. I'm old(er) myself. Transformers are good old solid engineering. This whole modernity thing where people feel better for no other reason than because today isn't yesterday is stupid... :-)

What I want to know is how you step up voltage without an inductor. I know it can be done without a transformer. That's after all how a boost converter works. I want to know if it can be done without an inductor though. If your inverter uses inductors to do this... that is cheating. You sacrificed galvanic isolation to gain a few points in efficiency. I understand why people do it. Lighter smaller inverter, better efficiency. What I don't understand is why that necessarily makes the inverter "better" :-)

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25 minutes ago, plonkster said:

Fine, I'll take your word for it. I'm not offended that my Victron is "old design"... don't care really. I'm old(er) myself. Transformers are good old solid engineering. This whole modernity thing where people feel better for no other reason than because today isn't yesterday is stupid... :-)

What I want to know is how you step up voltage without an inductor. I know it can be done without a transformer. That's after all how a boost converter works. I want to know if it can be done without an inductor though. If your inverter uses inductors to do this... that is cheating. You sacrificed galvanic isolation to gain a few points in efficiency. I understand why people do it. Lighter smaller inverter, better efficiency. What I don't understand is why that necessarily makes the inverter "better" :-)

lighter, cheaper and more efficient ;)

Using an inductor isn't cheating at all. it's just a different design. Copper is expensive and heavy

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7 minutes ago, SilverNodashi said:

Copper is expensive and heavy

But you see, large toroid inductors don't do much better. They are heavy and expensive, and they don't use much less copper. I understand the argument, it applies perfectly to the old LF designs with the iron cores. Iron is heavy. The "transformer" in the Victron is a Toroidal transformer. The material used for the core is the same as you use for your boost converter. The main difference between this setup and the boost converter used by others, is that the transformer has two windings on the toroid where the boost converter has only one. You gain single digit efficiency and you sacrifice galvanic isolation. I'll take the galvanic isolation, thanks :-)

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1 hour ago, plonkster said:

But you see, large toroid inductors don't do much better. They are heavy and expensive, and they don't use much less copper. I understand the argument, it applies perfectly to the old LF designs with the iron cores. Iron is heavy. The "transformer" in the Victron is a Toroidal transformer. The material used for the core is the same as you use for your boost converter. The main difference between this setup and the boost converter used by others, is that the transformer has two windings on the toroid where the boost converter has only one. You gain single digit efficiency and you sacrifice galvanic isolation. I'll take the galvanic isolation, thanks :-)

The coils in the Axpert is much smaller. someone took a pic of the PCB: http://www.4x4community.net/forum/attachment.php?attachmentid=355831&d=1437035361

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Just now, SilverNodashi said:

The coils in the Axpert is much smaller. someone took a pic of the PCB: http://www.4x4community.net/forum/attachment.php?attachmentid=355831&d=1437035361

Indeed, the coil in the lower left hand corner is about the same size as the one in my BlueSolar MPPT, and half the size of the one in my Multiplus.

Still, I remember the old LF designs... and the big chunk of iron those things had.

Attached a picture of my multiplus. 'Tis the small 1600VA, but take a look at the Toroid in the back, it has a diameter about as long as my hand. It's not the big heavy transformers of yesteryear.

1040493_10151711607125619_271056954_o.jpg

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So back onto the topic at hand, that WRND MPPT. I made a mistake in assuming the gate was shorted to the source on that MOSFET. Rookie mistake really, you can't really tell unless you take it out of the circuit. So I removed the burnt MOSFET driver, and now it measures open circuit as it should. So the MOSTFET is okay but the driver blew up. Traces on the board is destroyed, so there is no easy way to repair it. But there's 3 healthy boards I will do some more tests on.

Edit: The Plot thickens. The gate driver has a source and a sink pin, and in this case, it has a 1ohm resistor on sink, 22 ohm on source. You do this to control the rise and fall times independently. The data sheet warns that when you do this (asymmetric source/sink) , there will be a potential difference between the pins during switching, and if it exceeds 7.5V the chip will be damaged.

In addition, on the blown board, the 22 ohm resistor is open circuit. If the resistor went first, it would explain perfectly why such a potential difference developed and why the chip blew up. It is however also possible that the resistor got damaged during the short that blew the driver, though it looks perfectly fine. I'll have to rig it up and break out the oscilloscope :-)

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Okay, time to throw in the towel. Power supply is also completely shot and it wouldn't even light up when power is applied. I decided to apply power directly to the 5V side, with the current limiter on. Slowly cranked the current up and above 2 amps (!) it started booting. Then I cut the 5V line completely so that it is disconnected from the PSU and re-applied power. Now it came down to a more sane 350mA. This is JUST the controller board and the LCD with backlight, everything else is disconnected. That is pretty darn heavy. The Microcare unit needs more like 60mA... backlight included.

I think I can close this book. This thing is rubbish. Don't buy it.

Edit: So after a final bit of messing about -- mostly to attempt to figure out what frequency it drives those FETS at -- I thought it's perhaps good to revise my opinion on the current draw. The truth of the matter is that this thing is pretty broken all over. The Switch Mode PSU is shorted output to ground. I removed that, and applied a 12V supply to the 7805. It works, but everything gets very hot. I cannot imagine that it was designed this poorly. Even the microcontroller runs hot. I think the reasonable thing to assume is that even more things are broken down the line and that the current measurement cannot be trusted.

Now I'm really done with it.

broken_psu.jpgc

heavy_on_the_juice.jpg

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  • 11 months later...

Resurrecting a really old topic. This afternoon I thought... hang on, where are those bus bars from that old blown WRND controller... I wonder how much current they are rated for.

Google google... Oh, about 0.7A per square millimeter cross-section. Measure measure... so this thing is about 50mm square. The controller was rated for 120A... ostensibly...

buck_converters.thumb.jpg.1bdbc425e98468134cad5c722e1f2a02.jpg

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