Piggot's design wind generator 4'

[amiklic1]

Ok now. It's up in the air, and I have some data that I have measured till now.

Sorry for no pics, I'll put them on soon.

First of all, I made some changes to piuggot's original design. It was not made to improve something on design, but for easier building more units later.

Where I come from, it's pretty hard to find Opel wheel hubs. There is not much Opel Vectras with rear disc brakes. So I decide to build my own hub, and I made it with the help of my friend who has professional lathe workshop, and also all other tools necessary. I use SKF 25x55x13 2RS bearings. They are of closed type, so long life is expected.

I have to mention that all metal parts, excluding rotor disc, are made of high grade stainless steel ( marine type). So, no rust can happen.

I mount is on a 7 meters high steel pole ( 2" pipe ), with the base of two 2"x2" quad pipe. It's very easy to lift it or to put it down when neded.

I put 8 guy wires, 4 from the 80 cm below the top, and 4 from about 3m high.

And now, what I've measured:

My battery was as low as 6.5 volts. It is one old battery that I use no more for any serious job. I put it just to find out what I can except. With the help of winds of 15-30 km/h, it was filled to 11.5 volts for about an hour.

At open load, I got 30 volts at 29 km/h.

I took some other data, but I am still collecting it to form some kind of table and the graph, to present it here.

Today my regulator failed to switch the genny off to dump load, so it rotates very fast, and the pole and the guy wires were so noisy and vibrating that I thought that everything would blow apart. But, fortunately, that was not the case. I improvised one relay and switch to just use as kill-switch. It's working now, and probably would untill I change relay on regulator.

That's all for now, folks!

[Flux]

It would be much safer to connect your dump load in parallel with the battery rather than change over. Then if your relay failed you would still have the battery to hold things down.

To do it your way and be sure of holding it in a high wind you will need a dump load so low in resistance that it will act as a brake in normal winds.

Have you adapted a solar controller without changing it to shunt mode.

Flux

[amiklic1]

I made charge controller that can be used for both wind and solar ( at least that's stated at the schematics )of 16 Amps max ( with 555 circuit), and the relay on it was tuned to turn on the charging when battery voltage drops to 11.9 Volts, and to turn the charging off when it's 13.8 Volts. It was not supposed to work as dump load controller.

But, the relay has two-sided contacts, so , when the charging is turned on, it's on one side, and when not, it's on another side ( usual relay working basic). I used that other contact, that's connected when not charging batteries, and put a dump load on it.

I worked quite good for some time, but something failed, not the relay, but the potentiometers I use to tune the switching voltages.

What do you mean when say "Have you adapted a solar controller without changing it to shunt mode". I thought that I can do it this way. But it's obviously that's not the case.

[Flux]

Normal practice with wind is to use your relay to switch a dump resistor across the battery when it is fully charged, not to use a change over relay.

It is difficult to run a windmill on a dump load alone. A resistor low enough to dump all the power in a high wind will cause it to stall and stop in lower winds. If you choose a value that loads it fairly well in medium winds it will run away in high winds.

The constant starting and stopping is not good and you have the additional problem that a failure in the relay or dump resistor leaves your alternator running open circuit.

You just need to re-connect your relay so that you just switch the dump load on and off and leave the alternator constantly connected to the battery.

Choose a resistor for the dump load that will just keep the battery at float voltage in high winds when it is furling then it will not cycle on and off too often. With a simple on off control with one relay you will need a reasonable difference between on and off voltage so that your relay has a reasonable life.

Flux

[Jerry]

HI Flux.

I've expirienced what your talking about. Last winter we had a very windy day. when I got home from work my 48 volt battery bank was at 66 volts.

I real quik conected a 1500 watt heater element accross the batteries that brought the voltage down enuogh that the invertor would start up. After that the invertor kept the voltage in check.

I may ask your help to make that an atomated system this winter.

                             JK TAS Jerry

[amiklic1]

Here is my system as configured now. It's not very good schematic, but I hope you'll understand it.

Two wires that are directly connecting battery and the regulator are "sensor wires", which "tells" the regulator what's the batt voltage. If the battery voltage drops below some point ( e.g. 11,5 V), regulator switches on battery charging option, and switchess of dump load. If that voltage rise above some voltage ( e.g. 13,8 V), the dump load connection is switched on, and battery charging connection switches off.

If I understand you, I can connect one more wire to charge the battery even when dump load is connected to wind gen. Only, I have to put one large power diode in that line, so that dump load don't drain the battery.

I tried to figure that on other pic.

Is that good? If I missed something again, please point me to some schematic or so.

Thanks!

[Flux]

I assume your relay is connected like this.

If so change to this.

Flux

[amiklic1]

OK, thanks. that's wery simple, but you helped a lot.

I got one more question. If my battery voltage is currently 12 volts. Cut-out voltage is 13,8 volts.

Now, if the generator is putting 12.5 volts into the battery bank, the regulator would not switch on the dump load, but what will happen if the 12 volt voltage stays for a long period of time? It's still not battery's maximum voltage. Would my batteries start to boil after some period of time, even if they don't reach voltage maximum?

[Flux]

Your batteries can float indefinitely at 13.8v. If they are down at 12.5v they are still charging and will rise slowly to your dump voltage. If they don't there is a problem with them .

Normally for wind I would dump at a bit more than 13.8, perhaps 14v is a good compromise. Batteries will not boil until you exceed about 14.4.

I think you said you were testing with an old battery, if it has a bad cell then it may start to boil below 14v if one cell has a partial short.

Flux

[Flux]

Jerry

 The problem is the same but you need to be a bit careful with your set up as I seem to remember you have 120V dc. You have to watch what relays and contactors you use, dc rated ones are difficult to find and very expensive. With care you can use ac ones with a resistance load but you may need more than one contact in series to be sure that they will break the current.

Flux

[amiklic1]

 I find that connecting the circuit this way would cause dump load to drain batteries to 11.5 volts ( regulator's switch-in voltage). My regulator is connected so that it starts charging when voltage comes down to 11.5 volts, and quits charging when the voltage comes to 13.8 volts. I place the line in the picture to show the connection between battery positive and negative.

I mount one diode close to the battery positive connection, to prevent current leakage from the battery to the any kind of electronics and the dump load. I hope this is good. I think that only way would be to increase the switch-in voltage to some higher value, as my regulator is working at the principle of high and the low voltage to keep battery between.

Let's say that I change switch-in voltage to 13.5 volts. When the voltage comes to that value, the regulator would switch-on the battery charging. At 13.8 voltage it would switch-on the dump load, and keep it switched untill the voltage lowers to 13.5 volts.

I can see that battery voltage is about 0,6 volts higher when the generator is charging the battery. I can use that information to fine-tune the regulator. So, when you mentione d 14 volts, maybe that would be the right deal.

Also, if I short-circuit the battery for a second after charging stops, the voltage goes even lower. I'll try to measure that info and use it all to make some tuning.

[amiklic1]

Sorry for the bad picture, here is what I meant to send:

[Flux]

The diode is a good idea to prevent draining your batteries if the dump load fails.

You are right that 11.5v is too low. For lead acid batteries you can run down to about 12.4 v without taking any significant charge from the batteries but cut off dump at 12.6 and cut in at 14 to 14.2 would be better.

I seem to remember that you are using NiCd batteries so you may have to change the figures a bit. You need enough difference between on and off to keep the relay from cycling too often, but you need it to be off before you discharge the batteries more than a few %.

I think Nicd's drop voltage quicker than lead acid so that off at anything above 12v may be ok. I really have no experience of NiCd under these conditions and don't know if they exhibit surface charge. I was under the impression that voltage was no indicator of state of charge and you may have to work with a close ratio of on to off.

I forgot that you were not using lead acid.

Flux

[amiklic1]

Wen I give myself some thinking, why not to use just one voltage limit for the wind generator>batt setup. The max. voltage that the batteries can accept.

If I don't connect the lower voltage, and connect the generator to charge the batteries all the time, with dump load, I can see no harm in that.

[amiklic1]

Here are some pics of my windgen. I finaly found some time to upload the files.





This is my mountain cabin. In my area, cabins are made of stone, not of wood, as trees are not so high here. But we have too much stones that we can not get rid of easy. So we build walls, walls, walls....





Another picture from another angle, where you can better see the cabin, the tower and the genny.





Here is a closer look to my instalation. The genny is installed on a six meters ( 20') 2" pipe, and the anemometer (bicycle speedometer type specifier on this web page) is about 6' below that, mounted on some aluminium square pipe taken from sun shade construction.

Lower wires are momentary taken off the tower to make some mods.





Another closer look of genny. One can see the tail vane is not totaly verticall at the moment. Now I did correct that, even if that makes no difference working.





Genny when rotating, not with much speed. I did some investigations with camera, to make better pics of movement.





The same spped, but with other camera settings. Note the stainless steel salad-pot in front of the stator. It looks better that without it, to me.





Some higher speed. You can see that genny is not much above the trees, but as I have good winds here, I am totaly satisfied with output.





The back of the genny. I give it some red colour painted parts, and it looks good when rotating. Something like an old airplane rotor.





Another back picture of the genny and the anemometer, where can be seen not perfectly vertical tail vane.





That's me digging the hole in PURE STONE, for water tank. We plan to have lot of plants in our garden here, and thus we need much water. I found small hole about 1mx0.5m and 0.5m deep, and I make it some wider. Till now we have 15000 ltrs of volume.

My genny standed 155 kmh (97 mph) wind blow, and it's still good. The only problem was produced by me, when I was digging the hole with explosive, and part of a broken stone (nt too big, about 3cm, I guess) hit into one blade. I have repaired that, and nothing bad happened. I'll watch better next time.

Regards!