Hello everyone!

I have built a new small off grid system:

 

-Wind generator 600 W 3-phase AC 12/24V. MPPT regulator 12/24V

 

-1000 W PV-cells with dedicated MPPT regulator. Working well.

 

-24 V battery bank of 9,5 kwh.

 

Problem is that I cant get any charging current from wind plant.  I have replaced both the turbin and the MPPT-regulator but it is still not working. Yesterday we had good winds here in Stockholm (peak around 15m/s) with this readings.

Peak AC voltage 18 V. Average 7 V (L1-L2/L1-L3/L2.L3)

System voltage 25, 8 V

No AC current

No DC current

MPPT regulator has LED indication that indicate charging and battery connection.

Since this is my second turbin I start to think that it might not be possible to run it on a 24 V system ? Even if its sold and labeled as such. Any input apariciated!

My best

Patrick

5 hours ago, Ulltand said:

Hello everyone!

 

I have built a new small off grid system:

 

 

 

-Wind generator 600 W 3-phase AC 12/24V. MPPT regulator 12/24V

 

 

 

-1000 W PV-cells with dedicated MPPT regulator. Working well.

 

 

 

-24 V battery bank of 9,5 kwh.

 

 

 

Problem is that I cant get any charging current from wind plant.  I have replaced both the turbin and the MPPT-regulator but it is still not working. Yesterday we had good winds here in Stockholm (peak around 15m/s) with this readings.

 

Peak AC voltage 18 V. Average 7 V (L1-L2/L1-L3/L2.L3)

 

System voltage 25, 8 V

 

No AC current

 

No DC current

 

MPPT regulator has LED indication that indicate charging and battery connection.

 

Since this is my second turbin I start to think that it might not be possible to run it on a 24 V system ? Even if its sold and labeled as such. Any input apariciated!

 

My best

 

Patrick

 

Sorry to hear the Turbine is not pulling it's weight. 

A pity you could not find a fault prior to spending money on new equipment. 

I have no experience on wind turbines but I would say you need a much higher than 7V between any 2 phases. For a 24V MPPT you need an input of at least 28-29V. Unless there is a booster to boost the rectified AC to over 28V DC I am not sure if the MPPT can produce any output even if the LEDs are lit. 

Let's get members with experience to add to your problem and learn as we go along. 

What MPPT are you using?   Is it maybe the one below?
There is not much info on this, but it seems to be quite popular for low cost systems.

1 hour ago, Scorp007 said:

Sorry to hear the Turbine is not pulling it's weight. 

A pity you could not find a fault prior to spending money on new equipment. 

I have no experience on wind turbines but I would say you need a much higher than 7V between any 2 phases. For a 24V MPPT you need an input of at least 28-29V. Unless there is a booster to boost the rectified AC to over 28V DC I am not sure if the MPPT can produce any output even if the LEDs are lit. 

Let's get members with experience to add to your problem and learn as we go along. 

Thats whats puzzels me too. Is there some kind of a booster in the MPPT?  When I look around most turbins are rated 12 OR 24 volt. This one is rated both. Is it even possible?

20 minutes ago, Modina said:

What MPPT are you using?   Is it maybe the one below?
There is not much info on this, but it seems to be quite popular for low cost systems.

Might be the same inside?

 

No, these are different.  It has a extra LED (brake LED) It might be from the same manufacturer.  A newer model.

For the one I have posted, I have a back-engineered circuit diagram.  I have downloaded it some months ago but cannot remember the source.  I think it was a Youtube video with a link to the schematic.  It is referred to as a MPPT charger but it has no microprocessor.  It only contains a quad op-amp and a dual comparator with many bipolar and four MOSFET transistors.   Because it has no processor and not even preset potentiometers, I can only conclude that it is dedicated for lead-acid batteries.

Your MPPT seems to be made for Lithium batteries.  Judging by the very similar physical appearance, I suspect that it might still based on the same circuit, but with modifications for the charge voltage and some other tweaks.

 

1 hour ago, Ulltand said:

Is there some kind of a booster in the MPPT?  When I look around most turbins are rated 12 OR 24 volt. This one is rated both. Is it even possible?

Yes.  Small wind generators do seem to normally have a boost-converter topology.  And yes, it is possible to auto-detect your battery and adjust accordingly.  After all, many PWM Solar Charge controllers are also rated for dual 12/24V operation.

I first thought that your battery(s) might be Lithium (you didn't say what chemistry) and that the slightly higher voltage might be detected as a battery "full" condition by the charger.  Seeing that your charger is for, or at least supports LifePO4 batteries, that theory doesn't hold water.

You say there is no AC current.  I presume you measured in-line with one of the generator phases?  I would expect the AC to be loaded, i.e. an AC current flowing, even when no DC current is flowing into the battery.  This would likely be under the following conditions:  (1) battery voltage high (fully charged, and (2) AC voltage is over a certain threshold.  The reason that you measured zero current could be that the AC voltage was not high enough.

You will most likely not be able to read schematics, but I will attach the one for the other controller for the benefit of others on this forum.  Note that this is a back-engineered schematic and it is quite a complex analog circuit, so there could be some errors.

One would be able to connect a bench-top variable power supply to any 2 of the 3 input phases.  Then slowly increase the DC input voltage and monitor what the input/output current/voltage is doing.  For such a test I would first connect a small 12V lead-acid battery.  Then maybe repeat the test with a 24V battery.

Edited July 9, 20233 yr by Modina

Thanks a lot for your input!

I'm a mechanical engineer, so my understanding of the schematic is a bit limited, as you suggested. The batteries I'm using are lead AGM, which I forgot to mention.

I also bought a small 12V lead battery to test the setup at that voltage. However, the problem is that during this time of the year, most days are without wind.

If the generator has a pickup device for voltage, shouldn't I have had a higher reading than 18V in very good wind conditions?

I can manually spin the propeller to simulate wind speeds of about 7 m/s momentarily. Would that be enough for testing purposes? Or does the system need some time to react to charging?"

 

On 2023/07/09 at 9:39 PM, Modina said:

No, these are different.  It has a extra LED (brake LED) It might be from the same manufacturer.  A newer model.

For the one I have posted, I have a back-engineered circuit diagram.  I have downloaded it some months ago but cannot remember the source.  I think it was a Youtube video with a link to the schematic.  It is referred to as a MPPT charger but it has no microprocessor.  It only contains a quad op-amp and a dual comparator with many bipolar and four MOSFET transistors.   Because it has no processor and not even preset potentiometers, I can only conclude that it is dedicated for lead-acid batteries.

Your MPPT seems to be made for Lithium batteries.  Judging by the very similar physical appearance, I suspect that it might still based on the same circuit, but with modifications for the charge voltage and some other tweaks.

 

Yes.  Small wind generators do seem to normally have a boost-converter topology.  And yes, it is possible to auto-detect your battery and adjust accordingly.  After all, many PWM Solar Charge controllers are also rated for dual 12/24V operation.

I first thought that your battery(s) might be Lithium (you didn't say what chemistry) and that the slightly higher voltage might be detected as a battery "full" condition by the charger.  Seeing that your charger is for, or at least supports LifePO4 batteries, that theory doesn't hold water.

You say there is no AC current.  I presume you measured in-line with one of the generator phases?  I would expect the AC to be loaded, i.e. an AC current flowing, even when no DC current is flowing into the battery.  This would likely be under the following conditions:  (1) battery voltage high (fully charged, and (2) AC voltage is over a certain threshold.  The reason that you measured zero current could be that the AC voltage was not high enough.

You will most likely not be able to read schematics, but I will attach the one for the other controller for the benefit of others on this forum.  Note that this is a back-engineered schematic and it is quite a complex analog circuit, so there could be some errors.

One would be able to connect a bench-top variable power supply to any 2 of the 3 input phases.  Then slowly increase the DC input voltage and monitor what the input/output current/voltage is doing.  For such a test I would first connect a small 12V lead-acid battery.  Then maybe repeat the test with a 24V battery.

Hello

I opened the the first body and found some oxide on the tow contact, pic 1. After cleaning it (reduced impedance by at least 1,5 ohm)  i did a test with a 12 V batteri and *non* mppt regulator. When AC voltage exceed battery voltage the reguator starts charging. Problem is that this would require wind speed of about 10m/s.

For a 24 V system quite much higher. But with the MPPT reguator that will boost the voltage (on paper) i guess about 11m/s. Still this is way far from what they say in the specs " start charging in windspeed over 2,5 m/s"

Is this a comercial thing or is other manufactures that can do this?

Note that I have no practical experience with wind turbines so accept the following as common sense opinions, some of which could be inaccurate.
 

On 2023/07/10 at 10:14 AM, Ulltand said:

If the generator has a pickup device for voltage, shouldn't I have had a higher reading than 18V in very good wind conditions?

I am not sure what pickup device you are talking about.  If the 3-phase generator uses permanent magnets there should not be any sensor or controller and the output voltage will likely be a linear function based on rotational speed.

Permanent magnets cost money.  I would expect an alternator to have lower production costs.  Alternators use a field coil that needs to be excited, i.e. it needs power and that can be controlled if desired.  I am in no position to make claims as to what sort of generators / alternators are used.  I don't know the market, but I suspect that permanent magnet generators are likely.  At least this is the impression I get from some youtube channels.

 

On 2023/07/10 at 10:14 AM, Ulltand said:

I can manually spin the propeller to simulate wind speeds of about 7 m/s momentarily. Would that be enough for testing purposes? Or does the system need some time to react to charging?"

I would expect the system to react immediately.  You might be able to remove the blades and then drive the shaft with an electric drill for measurements and determine the output voltage curve.

 

10 hours ago, Ulltand said:

I opened the the first body and found some oxide on the tow contact, pic 1. After cleaning it (reduced impedance by at least 1,5 ohm)

A dirty slipring on a new wind turbine.  Mmm, that doesn't inspire confidence.  1.5 ohms is a substantial resistance.  If you get this setup to work, it might be a good idea to apply some special-purpose grease as those sliprings will not see any action in some sectors, so self-cleaning will be limited.
 

 

10 hours ago, Ulltand said:

When AC voltage exceed battery voltage the reguator starts charging.

No.  The regulator should contain a boost converter and it should start charging at substantially lower input voltage.  I would expect charging to commence at 6 or 7VAC.  At least for a 12V battery.  It sounds as if that MPPT doesn't work properly.  I know you said you have already replaced it....  

If I was in your position I would do some basic tests on the turbine itself, as you appear to already have done.  I would try to spin the turbine at different speeds and plot a basic transfer function of RPM versus output voltage.  With the confidence that the turbine can actually generated a decent voltage, I would hope that it can produce power (i.e. an output voltage under load) and I would first set aside the turbine.

I would then use a bench-top variable power supply - something like 0...30VDC at 1 or 2 amps should be fine, and test the MPPT charger.  I would  connect the PSU to two randomly selected input phases.  Your charger will have a 3-phase rectifier at the input, so it will be safe to connect a DC voltage with any polarity to any of the phases.  With a 12V SLA battery connected on the output of the charger, I would expect charging with an input DC voltage of no more than about 8 to 9V.  Then experiment by increasing the input voltage.  Note that depending on the voltage, battery SOC, etc. your bench-top power supply could/will run out of current and drop it's output voltage.  So a PSU that can output many amps would make for easier testing, but even with only 1 or 2 amps you should be able to confirm basic working of your charger.

If you don't have a bench-top power supply, see if you can borrow one or maybe buy a supply 2nd hand on ebay or whatever. 

Jus adding a pic of the inside and short clip running it with an electric drill

 

 

34 minutes ago, Ulltand said:

Jus adding a pic of the inside and short clip running it with an electric drill

 

 

With the maximum voltage out at 11.7V it means the MPPT must have a booster for it to work on 12/24V

1 hour ago, Scorp007 said:

With the maximum voltage out at 11.7V it means the MPPT must have a booster for it to work on 12/24V

Yes but I was a bit unclear, this test is with standard regualtor (1 st one not mppt). The MPPT i have has a boost up of 14 V on paper from what i learned. That would mean it need wind speed of around 11 m/s to start charging a 24 V system. Far away of 2,5 m/s from what they promise.  But then again there is very little enery in 2.5 m/s wind but at 7 m/s it would be great to get something out of the system.

Thinking of if more expensive generators would make a differens? Perhaps the design of coils and magnets are better?

Edited July 15, 20232 yr by Ulltand

It is really no challenge to make a boost inverter that takes 4 or 5VDC and boosts it to 26V or even 56V.  I mean, a typical taser will run from a rechargeable 3.7V and make 12KV or more.  😁     My first statement is not meant to mean that I suggest you build your own, but rather that your MPPT should have no problem boosting a voltage from say 4.5VAC to 26...27VDC required to charge a typical 24V lead-acid battery.  I think your problem is likely to be found with that MPPT.   I realise that wind generators do not have a huge selection of MPPTs available....  MidNite Solar seems to make some decent ones, but I think they are American and will likely cost a fair bit of money.

An alternative would be to buy a buck/boost converter with voltage and current limit adjustment capability and then use that as your battery charger.  You would also need to buy or make your own 3-phase full-wave rectifier but that is cheap and easy.  The only downside is that this setup would not include a turbine brake system, for times that your battery might be full and high winds might cause the turbine to over-rev.  For that you could use a over-voltage protection module which could switch a ballast resistor across the rectifier output at a certain pre-set voltage.

My view is that wind generators are only for very specific applications.  If you are really 100% off-grid in a very remote location.  If you really know how to safe every last watt and you desperately need a backup to a solar panel system.  I personally would first want to get this current system to work and get some experience with using it.  See how much power you can get during a specific season.  Upgrading can be considered at a later stage.  There seem to be a lot of unhappy wind turbine owners that sit with systems that have been completely over-sold and fall far short of power expectations.