Beginning in 2007, I have been building and testing custom-made wind turbines in my spare time. This site was written to share my experiences and methods with others interested in doing similar projects.
Giving the site a long-overdue face lift. Sorry for any inconvenience.
Davis Vantage Pro 2
Here are some sites where I have found useful information:
Sincere thanks to the many people who have helped and encouraged along the way. For years I have pursued my interest in building and using wind turbines for electrical power on my acreage home. I have encountered many helpful people and resources along the way. Without them, I might still have nothing off the ground.
Here is where I can “give back”, by putting notes and lessons together into one place, where others can read and learn for themselves. I hope they find it helpful. I especially hope that people new to the hobby can be inspired.
I am always open to feedback, too, so write me an e-mail any time.
Somewhat sad news, I have lowered the Spirit of Zubbly-II for an extended break.
Nothing wrong with the turbine!
No, it is in fact the infrastructure around the turbine that is no longer up to the task. There are many problems that have literally been growing around it:
- A wall of poplar trees to the west
- A wall of pine trees to the south
- Excessive twisting that I can’t get out of the drop-cable
- Failing battery cell
These small problems have combined to major problem that I can only fix properly by relocating the tower and replacing the battery. For that I have to completely dismantle the system.
I will have to live without this living, breathing machine in my yard this summer.
The deciduous trees to the west side have grown from a meagre 30 feet when I moved here to a staggering 60 feet tall – much taller than any poplar trees in the county. They are a minor obstacle in the winter when they shed their leaves, but for the summer months they block 1/2 of the prevalent winds.
The pine trees south of the turbine are more of a safety issue. Planning to cut them down when they were small many years ago, they have proven to be a good snow barrier in the winter and we no loner want to remove them. They now entangle the tower’s guy wires as I raise and lower it, making a dicey operation even more difficult.
The twisted cable in the tower should be simple to solve but some shortcuts I took when I first built it now prevent the pendant cable inside the tower from twisting freely. The winds here turn almost exclusively clockwise, at least once a week, so many twists build up, and it’s becoming a maintenance headache to lower the tower, dismantle it partly, just to get the cable untwisted.
There’s almost nothing I can do to stop the weakest cell in the battery pack from failing. It is nearly 20 years old, now. They are already living in grace but this was inevitable. The bad cell is now several percent weaker than the rest and falling quickly. If it remains connected it will draw down the rest, which is suicide for battery packs.
6-Month Maintenance Update
Blades look none the worse for wear so far. Of course, it hasn’t been exposed to hail yet.
Items on the agenda:
- New bearings in the generator
- Re-mount the magnet rotor on the shaft.
- Remove speed sensors in the generator, since my current tachometer works better
- Re-wire tower for only 3 power wires (no more need for star/delta/jerry switching)
- Re-wire generator for permanent parallel-star operation only
- Re-varnish blades
- Apply extra erosion protective tape
- Re-grease tail
- Thorough cleaning and inspection of absolutely everything else.
For those who like to keep track, 6 months of operation averaging 200 RPM is about 50 million revolutions.
Several important changes going from the 8-ft blades to 10-ft blades:
Obviously, much more torque. The shorted-phases does not maintain a stop in strong winds like it used to.
Previously I had a star-jerry switch which would break the star-point and rectify phases separately. There is no longer any point in doing this, and it runs continuously with the phases connected in Star.
I have processed the datalogger output many times now, and the power curve is superb at low wind speeds. I have never seen a commercially-available WT with any output at 4 mph wind but Zubbly-II does. So it spins every day and it’s only stopped when it’s dead quiet around. It does not have spectacular peaks of power but I do not need them.
Furling keeps it behaving very calmly. Mostly below 400 RPM, but I’ve measured some peaks above 500 for less than a second. In a certain frame of mind, one would want to ease off the furling and let the power peak up a bit more. But after looking at typical wind speeds in my area it turns out there’s not much point. Raising the peak from 400 to 500 Watts would not matter very often.
I’ve done some speculative predictions of annual energy output, which comes out around 1000 kWHr per year.
So all in all, doing very well.
Finally ready to raise with new 10-foot (3 meter) diameter blades.
Now it’s up.
The trees you see are becoming a problem!
The tower tilts down between them and it’s difficult to prevent the cables from being entangled.
Just before final assembly. Here is the last step finishing the blade – adding balancing weights in the tips.
You can barely see it… if you look carefully you might be able to see that there is a clear protective tape on the leading edge of the blades.
It resists erosion and sticks very well.
Spirit of Zubbly was lowered for servicing today. In the end, just grease on the tail shaft and yaw bearing were needed. A squeak had developed, which could only be heard during storms strong enough to raise the tail, so it was obvious where it was coming from. When I disassembled the tail’s pivot, I found nothing but grime was left inside. Since I never did anything to seal the grease in, I just cleaned the pivot, re-greased it, and I’ll cross my fingers for another 2 years noise-free.
Speaking of grease (remembering a previous discussion on the subject) the shaft bearings are running as smooth as ever and I haven’t heard any squeaks on deep-freeze days like I was before.
Nothing was particularly rusty or needing work, but I sprayed a bit of paint just to pretty it up again. The rubber tail bumper has some cracks but is still solid, while the rubber vibration dampers have no cracks and are still firm.
No loose bolts were found and normal play was found in the moving joints. The blades will need to be re-finished in the summer. Every time I work on this machine, I silently say “thanks” to the guy who inspired the project and showed me how to make a durable and effective machine.
I have christened my latest wind turbine the “Spirit of Zubbly”. It is named after a custom wind turbine builder whose projects are popular and passed away 5 years ago. I don’t want Zubbly’s contributions to the art of home-built wind turbines to be forgotten. By dedicating this project to his inspiring work, I hope to remind everyone about the value of being creative and inventive, and sharing knowledge with others. It’s the spirit of both science and art, and it’s what makes projects like this so satisfying for me.
I’m finally done (almost), and it’s up in the air. What a cold day for finishing this off (-12C / 10F!). This years’ project was pretty complicated. Many things are changed, although many basic parts of the turbine remained the same. It still has the 8-foot diameter rotor blades, and the generator is the same motor-conversion I did a couple of years ago.
Wood blades and a motor-conversion: at its heart it is still a Zubbly-inspired wind turbine.
Improvements to the tower and the rest of the system meant that the entire system was taken apart all summer. It was also an opportunity to re-finish the blades and do some experiments with improving the generator. Some will remember that I had difficulty removing the old bearings from the generator’s shaft, but that mess was minor compared to the piles of parts littered about as I went.
In all, this is what I changed:
- The tower is taller by 10 feet, getting above my trees (which don’t stop growing, dammit), now 50 feet tall.
- The tower also has an additional group of guy wires to support the extra height.
- Yaw-mount and chassis were re-designed to allow vibration isolators under the generator.
- Tail re-designed to have a complete 90 degree swing when furled, and a harder running position.
- Re-organized all batteries/inverter/charge controllers in a new building.
- New underground cables buried from the new building to the tower and solar panels.
Adding height to the tower put higher loads on the gin pole and winch cables, so I made the gin pole longer. Halfway through working on that, I realized that rather than extend the gin pole, it was far easier to add a pulley to the end of the gin pole instead. The pulley reduces the winch cable tension in half, which was the critical part of the equation. An unrelated project from last year had left me with a 10,000 pound load cell and a nifty program to monitor tension loads, so I used that to check that I wasn’t going to over-stress the cables, and keep a very safe margin.
Last winter, an annoying noise took hold of the turbine. I resolved to eliminate as many sources of noise by building a chassis for the generator that would include vibration isolators under the generator mounting feet.
I came up with a way to assemble a set of pads, inspired by old-fashioned aircraft engine mounts, that would be easy to assemble, and avoid buying anything expensive. All I needed were flat sheets of neoprene to cut to fit as needed.
The frame of the chassis supports the feet of the generator with four over-sized bolt holes. By over-sizing the bolt-holes, there is room to slide in tubes of rubber, fitting snugly and allowing each bolt to pass through. On either side of that are rubber disks about 1/4″ thick. Large washers put bearing pressure on the pads as the bolt is tightened up. The generator sits on top of the assembly, resulting in no metal parts of the generator being in contact with the chassis.
The arrangement is, I admit, better at absorbing high-frequency noise rather than the low-frequencies that are giving me trouble, but I don’t think it will hurt any, either.
I also managed to build in the right sized hole for a kellum grip to hang neatly at the top, supporting the drop cable inside the tower. I hope to avoid the terrible amount of twist that had developed by the time I took the tower apart (about 15 complete turns CCW).
During the summer, my wife and I moved a number of our “movable” buildings to make room for a new one, and to make it easier for trucks to turn around in our barnyard. We chose a shed that wouldn’t be needed any more to become the new home for the batteries, and electrical room for all the RE projects, so I call it the “Batt-cave”.
I haven’t insulated the compartment around the batteries yet, though they are enclosed for protection, now. Everything is accessible, wiring is sized out of the NEC, and I have more places with protection and shut-off means than I did before. Got all enclosures bonded to ground, too. I won’t be sure I have all the details sorted out right until I draw a new schematic. It works, that’s all I can say.