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Marlec Wind turbine 24v to 48v

John2121

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Joined
Oct 23, 2022
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9
Good Morning All
Quick question, I have a wind turbine currently not being used. I believe it is set up on a 24V charge controller.
The existing solar system is now 48v
I do not know the model of the turbine but was told that it produces 120V and that all I need to do is switch the controller to a 48V one.
My question is around the 120V output, as when I go on their website the turbines all have selections for 12, 24 and 48v which then makes me wonder if the turbine itself is linked to the voltage outputs and not just the controller.
Any ideas?
Thanks
 
I do not know the model of the turbine but was told that it produces 120V and that all I need to do is switch the controller to a 48V one.
My question is around the 120V output, as when I go on their website the turbines all have selections for 12, 24 and 48v which then makes me wonder if the turbine itself is linked to the voltage outputs and not just the controller.
Any ideas?

Long answer:


Pretty much all home wind turbines will have this set-up

1666569506916.png

Some of them might not have the dump load.... but I would avoid any that don't.


The wild AC voltage spec for the windmill will be for running the system at the optimum level. However, the wild-AC is coming off the generator so the frequency, voltage, and current will vary wildly. Most of the generators are going to put out 3-phase AC, but once in a while you will see one that puts out single phase. (Single phase will have two power wires and 3 phase will have 3 power wires). The Wild AC is not suitable for running an AC appliance.

The Bridge rectifier can be stand-alone, built into the generator, or built into the controller. Consequently, you may not be able to identify an independent component called the bridge rectifier, but it is in the system someplace. (A really cheap system might have a half-bridge rectifier, a good system will have a full-bridge rectifier)

The output of the bridge rectifier is a noisy 'pulsed' DC. The pulsing will be at a frequency that is 2x the Wild AC frequency and the voltage will be close to the same voltage as the wild AC.

The controller is responsible for converting the Pulsed DC to the proper current & voltage for the battery. If the generator is creating more power than the system can take, it will either short the inputs to the controller and let the coils of the generator dissipate the energy or divert the energy to a dump load. (I much prefer systems that use a dump load. It is a much 'gentler' control and is easier on the generator)
 
Long answer:


Pretty much all home wind turbines will have this set-up

View attachment 117570

Some of them might not have the dump load.... but I would avoid any that don't.


The wild AC voltage spec for the windmill will be for running the system at the optimum level. However, the wild-AC is coming off the generator so the frequency, voltage, and current will vary wildly. Most of the generators are going to put out 3-phase AC, but once in a while you will see one that puts out single phase. (Single phase will have two power wires and 3 phase will have 3 power wires). The Wild AC is not suitable for running an AC appliance.

The Bridge rectifier can be stand-alone, built into the generator, or built into the controller. Consequently, you may not be able to identify an independent component called the bridge rectifier, but it is in the system someplace. (A really cheap system might have a half-bridge rectifier, a good system will have a full-bridge rectifier)

The output of the bridge rectifier is a noisy 'pulsed' DC. The pulsing will be at a frequency that is 2x the Wild AC frequency and the voltage will be close to the same voltage as the wild AC.

The controller is responsible for converting the Pulsed DC to the proper current & voltage for the battery. If the generator is creating more power than the system can take, it will either short the inputs to the controller and let the coils of the generator dissipate the energy or divert the energy to a dump load. (I much prefer systems that use a dump load. It is a much 'gentler' control and is easier on the generator)
Thank you for taking the time for this reply. This makes sense to me now I think. The wind turbine will generate random voltage output dependent on wind speed (but probably limited to a max). So the charge controller then does the job to stop damage to batteries. I will have to ask about the dump load as this is something I have not heard about.
So I can just change the charge controller to get the unit up and running again as long as its the right controller and everything is in order.
I assume when these companies have their drop down menu for which Voltage 12/24/48, it is the controller that is the difference and not the turbine itself
 
The wind turbine will generate random voltage output dependent on wind speed (but probably limited to a max). So the charge controller then does the job to stop damage to batteries.
Correct.....except for the 'limited to a max' part. Read on.

I will have to ask about the dump load as this is something I have not heard about.

With a wind turbine, if there is no load on the generator, there is little resistance to the spin of the blades. This means the blades can spin faster than they are designed to handle and the voltage will go way up. (This is called free-wheeling). At a minimum, this will wear out the bearings faster. At worst, the turbine can actually tear itself apart if there is high wind and no load. Furthermore, the high voltage could possibly cause damage to down stream electronics.

What this means is that there should always be a load on the system. Consequently, when the battery is full and no longer taking current the controller must send the energy into what is known as a dump load. This is often a bank of high-wattage resisters that turns the energy into heat. Some people will use heating elements in a hot water tank as the dump load so they can make use of the excess energy.

Some controllers just short out the inputs. This makes the coils in the generator heat up and dissipate the energy. (The coils become the dump load) This is usually done on lower-cost set-ups and in general, I would avoid systems like this. However, people have reported good performance and reliability from this type of system. It can be a bit of a crap shoot whether any particular system that does this was designed well enough to handle it.

Even controllers that use dump loads have a wide range in how well they work. Some of them have a simple relay that switches to the dump load at a predetermined voltage. This can cycle on and off very rapidly and be very jarring on the turbine. The best controllers have a sophisticated PWM system that gradually transitions to the dump load as the voltage goes up.


I assume when these companies have their drop down menu for which Voltage 12/24/48, it is the controller that is the difference and not the turbine itself
Maybe....maybe not. Sometimes the generator coils are different. You would need to check with the manufacturer to be sure.

Before you spend any money on this make sure you have a place where you are going to regularly have a steady wind or you will be disappointed. Also, look very closely at the specs of the system. Some of the cheap hacked-together windmills available on ebay and aliexpress claim a wattage that is only possible in near gail-force winds and produce almost nothing in slower winds. If they don't provide some kind of wind-speed vs power output chart, be suspicious. If they don't tell you the wind speed needed for the rated power output, be very suspicious.

I had a quick glance at the Marlec website and they seem OK. They don't look like garage-shop turbines with repurposed generators and a blade.... However, websites can be deceiving, I did not look closely, and I have no experience with Marlec so I can not say either way.

A couple of side notes:
  • Water turbines have the same problems with free-wheeling and usually need dump loads as well (Particularly high-pressure, low-volume water turbines. Low-pressure, high-volume systems turn much slower and are less susceptible to problems for free-wheeling.
  • Solar Panels don't have this problem. When the solar charge controller turns off the current, the panels just absorb the suns energy and get hot. The panels are designed to handle it.
 
Correct.....except for the 'limited to a max' part. Read on.



With a wind turbine, if there is no load on the generator, there is little resistance to the spin of the blades. This means the blades can spin faster than they are designed to handle and the voltage will go way up. (This is called free-wheeling). At a minimum, this will wear out the bearings faster. At worst, the turbine can actually tear itself apart if there is high wind and no load. Furthermore, the high voltage could possibly cause damage to down stream electronics.

What this means is that there should always be a load on the system. Consequently, when the battery is full and no longer taking current the controller must send the energy into what is known as a dump load. This is often a bank of high-wattage resisters that turns the energy into heat. Some people will use heating elements in a hot water tank as the dump load so they can make use of the excess energy.

Some controllers just short out the inputs. This makes the coils in the generator heat up and dissipate the energy. (The coils become the dump load) This is usually done on lower-cost set-ups and in general, I would avoid systems like this. However, people have reported good performance and reliability from this type of system. It can be a bit of a crap shoot whether any particular system that does this was designed well enough to handle it.

Even controllers that use dump loads have a wide range in how well they work. Some of them have a simple relay that switches to the dump load at a predetermined voltage. This can cycle on and off very rapidly and be very jarring on the turbine. The best controllers have a sophisticated PWM system that gradually transitions to the dump load as the voltage goes up.



That is probably true.... but it is not a guarantee. You would need to check with the manufacturer to be sure.

Before you spend any money on this make sure you have a place where you are going to regularly have a steady wind or you will be disappointed. Also, look very closely at the specs of the system. Some of the cheap hacked-together windmills available on ebay and aliexpress claim a wattage that is only possible in near gail-force winds and produce almost nothing in slower winds. If they don't provide some kind of wind-speed vs power output chart, be suspicious. If they don't tell you the wind speed needed for the rated power output, be very suspicious.

I had a quick glance at the Marlec website and they seem OK. They don't look like garage-shop turbines with repurposed generators and a blade.... However, websites can be deceiving, I did not look closely, and I have no experience with Marlec so I can not say either way.

A couple of side notes:
  • Water turbines have the same problems with free-wheeling and usually need dump loads as well (Particularly high-pressure, low-volume water turbines. Low-pressure, high-volume systems turn much slower and are less susceptible to problems for free-wheeling.
  • Solar Panels don't have this problem. When the solar charge controller turns off the current, the panels just absorb the suns energy and get hot. The panels are designed to handle it.
Thank you for the very detailed response! Its actually an existing turbine so I am only considering this because the cost may be low to get it running and worth seeing if it helps support the existing solar setup I have. It is in an open area so that bit should be ok. They just seem to have positioned it a good distance from the batteries and where the controller would be (40 - 60m) so power loss on the cable may be an issue, but the cable was sized up apparently because of this.
I have also emailed Marlec about the voltage.
Just trying to get a feel to see if its worth the cost to try.
 
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