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_ Day 14
At last I can get back to building the charge controller, for some reason I’m looking forward to this bit so I assembled all the components loosely, without soldering, onto a DIY circuit board which I call Vero board, presumably the company name who makes it.
I followed Mikes link & rearranged the components until it resembled the correct circuit, I also marked the tracks that needed cutting for the circuit to work correctly.
After a double check that everything was going to work ok I soldered the components in place & cut the tracks where necessary.
I have a small hand held tool specifically designed for cutting these tracks, if you don’t have one you can use a knife or a small drill.
I connected all the wires, relay & terminal strips & it works fine. I don’t have an adjustable DC power supply to set the low & high voltage pots so I drained a battery to get the lower voltage & I’ll wait until the battery is charging to set the high point, not ideal but it will work. Update, I now have an adjustable DC power supply which makes this & other projects far easier.
I’ve left the wind turbine on test for about a week & have noticed a few areas that need attention. The first being that the turbine is very easy to turn on the end of the scaffold pole, I had originally thought that because I’m not using a bearing assembly such as an old wheel hub that it may not turn so smoothly. It’s actually a bit too easy & with a slight breeze it will turn but far too often which could result in the cable being twisted inside the pole. To overcome this I could either reduce the size of the wind vane or reduce the length of the horizontal vane support arm. Reducing the arm length seemed easiest so I’ve reduced that by 110mm which now butts the vane up against the end of the timber where as before it hung over the end.
The other thing I had noticed was a bit more serious, the turbine needs a very strong wind to get it turning, once it’s turning it’s ok. I suspected this is due to using home made blades made from plastic pipe but I also noticed that the turbine blades do not spin freely even when pushing them by hand. This is due to something called cogging which you can feel when turning the blades by hand, it is the magnets being attracted to the iron core (the iron core is what the copper wire is would around). When you turn the blades the magnets wants to hold the blades back until the magnets turn enough to then be attracted to the next iron core & at this stage they move a bit easier, then the process starts all over again. This can be overcome by filing down the iron core as per the pics, this will minimise the problem & really help the turbine start in low winds.
I devised a simple gauge to help me measure the amount of cogging, it’s just a piece of wood that replaces the blades & I can hang weights off of it which gives me some idea of how much cogging there is & how much better it is getting due to filing. The idea is to record the max weight before the turbine spins, I used some homemade lead fishing weights which worked well but you can use anything really. I filed the iron core as per the pics & have reduced the cogging by 50%, which equates to hanging 460g @ 250mm from the centre of the turbine, you can use any length of wood for this but just ensure the centre mounting hole in the wood is exactly in the middle of it’s length & then it will be balanced & not affect the gauge.
The turbine is back up now & I will have to wait for some wind to see if the changes have made the necessary improvements.