DIY Wind Turbine - Part 5 - Updates

Well i have been so busy lately i have not had a spare second to post any new blogs, but it's getting to the point now where i need to catch up a bit. The foum has taken off a bit and i have been inundated with users requesting custom groups, and a large number of moderation jobs, this has tied my hands, but today is a little more relaxed so i thought i should spend the time on some DIY Wind Turbine updates.

During testing of the Better Blades from part 4 i noticed that the output of my 180V DC motor was not as expected, the blades worked a treat, and the turbine spins well in very low wind, producing between 4-8V, in high winds this exceeds 15V but how often do we get those high winds, this is simply not suitable, the battery will never get recharged. I decided to focus my attention on boosting the output voltage of the turbine with a voltage doubler, so i purchased a 6-12V DC voltage doubler (input range 4-11V, with over 90% efficiency), this should do the trick as the average output of the turbine is 6V .

I eagerly awaited delivery of the voltage doubler, and when it came i was straight on the case, it was wired into the system in about 5 minutes... again typically when your trying to test a wind turbine, no wind, not even a nats fart. I waited for 2 days and then, a slight breeze, the turbine spinning away, and for once a green charge light on my battery charge controller, yay, the doubler output voltage was around 12.5V.

Impatiently i had used the inverter and battery to charge my mobile phone and laptop a couple of times so the battery voltage was slightly depleted, i measured the voltage from the battery terminals which was 11.36V, i left the sytem for 45 minutes and returned to measure again, i waited until the turbine had stopped spinning as this might affect the results, the new measurement was 11.52V.

Ok so it seems that the voltage doubler is working but over the next few days the voltage barely increased, and the charge light was on more or less 50% of the time, i then decided that the initial increase in voltage was due to stabilisation after i had finished charing my phone and not from the wind turbine. So what is the problem, the voltage doubler uses a circuit that halves the current in the system in order to double the voltage, and with losses in the components the output current from the system was quite low even though the voltage was high enough to turn on the charge controller. I noticed that this was the case when i tried to turn the turbine by hand, it was a lot harder to turn compared to before the voltage doubler was installed, this means that there is more load in the system introduced by the voltage doubler components.

So most of the energy produced by the turbine was being wasted in the doubler components. This situation is not suitable, and currently the system cannot produce a sustainable electricity supply, so since discovering that a voltage doubler circuit does not do what i had expected i am now looking for an alternative DC motor, a motor that will hapily develop 12V in low wind speds. This is also the reason why i had not posted about the mountings, a different motor will require a different mounting as my original motor already had a bracket that was modified to suite the purpose.

Once i get my new motor, mount the blades and test its output i will move on to the mounting.