Well it is not good news. Seems that the Sunforce Wind Generator does not work well. We believe that they may have over complicated the generator package to make it easier to use and ended up making it almost useless. The key problem is that it refuses to charge our battery. We watch the generator spin up in a good wind while monitoring the voltage and current at our battery. The blades spin up and there is an initial supply of current then the current goes to zero while the prop slows down. Read more after the jump.
We really like this wind generator and can see that it should work great for our application but it is not functioning well for us. It could be defective or something about our installation is causing problems. We (my Dan and I) are both experienced electronics engineers, it is not likely that we have a minor electrical problem.
The basic problem is that it will not maintain charging current into a battery during a strong wind. In fact it disconnects from our battery and engages it’s own internal dummy load to protect the prop. It sits there in a nice wind spinning up then breaking, releasing, spinning up, releasing. We see the current come up a bit then turn off as the motor is breaking. It appears as if the internal control system believes it is necessary to feather the prop rather then apply current to our load.
What may be happening is that as the load current comes up, the voltage drop on the feed from the generator to the battery will also go up. The internal computer is measuring the voltage at the generator and may believe that the output is not loaded. It then switches in a dummy load to feather the prop. We did try setting the voltage adjustment as high as possible but this did not work either.
In our installation we have about 120 feet of 12AWG outdoor Romex cable. The voltage drop on this would not be large. The wiring should be sufficient for this application. For the battery we have a 12V Deep Cycle Marine Battery.
It seems that a two part system or a sense wire is needed to make this system function well. The internal control system does need to monitor the battery voltage to protect the battery. But if you have some voltage drop in the voltage will seem higher then it really is. A sense wire to measure the voltage without the current and therefore voltage drop would be one answer to this problem.
Another solution would be to feed down the raw generator output and have a separate charge controller. This may add the cost of a second enclosure but it has the added benefit of not loosing energy in the feed cable. A higher voltage can be passed from the generator to reduce the current and therefor the loss in the leads. The remote charge controller could also include status indicators which would not be usefully on the generator body, 30 feet in the air.
Maybe Sunforce expects you to mount the battery up on the tower next to the generator. This would reduce the voltage drips and might solve the problem as well. I doubt that users would be happy with that solution.
I believe the generator will deliver power but that placing the charging system in the generator is not practical. It makes the overall system easier to install and lower in cost but the voltage drop on the feed lines are a significant issue. I would like to see this product adjusted to include battery sense lines. This would remove most of the voltage drop issues. Allowing the control circuitry to correctly monitor the battery charge state.
In the previous post about this project I described our installation. If the Sunforce Wind Generator does not support this use then I needed to update everyone that it may not work as we have it installed. I believe our use is reasonable and many of you may be saved considerable headache by learning of our experience.
I hunted down a support email address and will ask for support. We will do another update once we get this all sorted out. For now, I cant recommend that anyone purchase the Sunforce Wind Generator if they plan to use it as we did, with a long power cable between it and the battery.
We are also playing with solar panels, more to come on that project.