graeme jones Posted August 31, 2015 Share Posted August 31, 2015 On a recent holiday to Anglesey, I was interested to see boats moored in a marina using small wind turbines for electrical power. Now that I've started in a bit of competition work I need a way to charge flight batteries (12V 50W charger) and keep my food cool (12V 50W fridge). My car battery and leisure battery combined can only supply 100W for about 8 hours ( with a 50% safety margin to avoid deep discharge). I've looked at small wind turbines by a couple of manufacturers but prices start at £600! Has anyone out there built their own or experimented with such a device? I'm thinking along the lines of a medium size brushless motor and a five blade turbine of about 500 mm diameter, but can't figure how to match the slow speed of the turbine (1000 RPM?) with the KV of any available motor. Gears to match the speeds mechanically would be noisy and reduce efficiency. Any ideas? Graeme Edited By graeme jones on 31/08/2015 16:00:16 Quote Link to comment Share on other sites More sharing options...
Phil 9 Posted August 31, 2015 Share Posted August 31, 2015 would solar panels not be more suitable for your needs Quote Link to comment Share on other sites More sharing options...
graeme jones Posted August 31, 2015 Author Share Posted August 31, 2015 Phil - I have a couple of solar panels, of the briefcase type from Maplin. Rated at 13W each I bought them for £40 pound each when they were on a halfprice offer. Rated at 13W each they produce a maximum of 1.4 amps when used in parallel. To produce the 8 amps I need means solar panels rated at 150W, costing at least £500 and weighing more than I could carry. And the sun would need to shining. So no good at night or in typical British weather. Of course wind turbines only work when the wind is blowing, but it always is when I go flying, usually too strong and in the wrong direction! Graeme Quote Link to comment Share on other sites More sharing options...
Don Fry Posted August 31, 2015 Share Posted August 31, 2015 Be aware that any machine producing power will produce noise. On the average campsite, or even ad hoc sites like the nats or club shows, you may fall foul of the etiquette of silence at night. Then beware. A small petrol generator, used in the day may be your answer, not green but actually does the job. Of course a child on a generator bike, driven by bribe, or fear, has to be good for a 100 watts, and as they can be enclosed, you can lose the noise. Just a thought. Quote Link to comment Share on other sites More sharing options...
Foxfan Posted August 31, 2015 Share Posted August 31, 2015 A lot of boat people used 12Volt alternators, mounted in pudding/mixing bowls. Not sure what they did for propellors though, but there were many home mades around when we lived afloat. Perhaps the canal forums would divulge? Might still be cheaper to buy more spare batteries! MrTin Quote Link to comment Share on other sites More sharing options...
graeme jones Posted August 31, 2015 Author Share Posted August 31, 2015 Donald - the turbines I saw produced very little noise, but I take your point. Although with a leisure battery to run the fridge overnight the turbine could be stopped, the wind often drops at night anyway. Not sure I agree about the "etiquette of silence" though. I had to come home from the Nats early Sunday morning because I had no sleep at all Friday or Saturday nights. Dogs barking, people laughing and shouting, car doors being slammed, cars being driven about (I think by people who couldn't be bothered to walk to the toilets), quadcopters being flown - all of this until at least 2 AM, I doubt I would have been able to hear a small turbine myself. Oh, and of course there was what I assume was a disco in the trade area, which didn't even start until 11:30 PM. And farm machinery in the distance. And some caravans/motorhomes with generators left running despite the campsite rule that they be turned off by 11:00 PM. And all of this was in the QUIET part of the campsite. How much worse was the NOISY part? Yes, a small petrol genny would be an answer, but a good, reliable quiet one would be expensive. Foxfan - yes I've had a look at some of the canal forums but most seem to use large solar panel arrays or a commercial version of what I'm thinking about. Not sure whether you mean more flight batteries, which wouldn't solve the problem with the 12V fridge, or more leisure batteries, which are expensive and very heavy (I would need at least 6 80Ah batteries to give the required energy storage). Graeme Edited By graeme jones on 31/08/2015 20:31:21 Quote Link to comment Share on other sites More sharing options...
Braddock, VC Posted August 31, 2015 Share Posted August 31, 2015 Posted by graeme jones on 31/08/2015 15:59:45: On a recent holiday to Anglesey, I was interested to see boats moored in a marina using small wind turbines for electrical power. Now that I've started in a bit of competition work I need a way to charge flight batteries (12V 50W charger) and keep my food cool (12V 50W fridge). My car battery and leisure battery combined can only supply 100W for about 8 hours ( with a 50% safety margin to avoid deep discharge). I've looked at small wind turbines by a couple of manufacturers but prices start at £600! Has anyone out there built their own or experimented with such a device? I'm thinking along the lines of a medium size brushless motor and a five blade turbine of about 500 mm diameter, but can't figure how to match the slow speed of the turbine (1000 RPM?) with the KV of any available motor. Gears to match the speeds mechanically would be noisy and reduce efficiency. Any ideas? Graeme Edited By graeme jones on 31/08/2015 16:00:16 To get anywhere near the power you want you'll need a wind speed of at least 18 mph, not conducive to flying. To keep your grub cool put it in a metal biscuit box cover with a thick towel and soak with water. if you put the tin in a flat container filled with water with the end of the towel in the water it's self perpetuating until the water runs out, This will work when it's windy and when the sun shines. The evaporative potential is pdg but it will only cool not chill the tin. Battery charging done from the ciggie lighter on the car. Personally the machine mart 1 kW inverter genny pulls the stunt for me, runs my lap top, tv fridge etc and is pretty quiet too. It's around £250 and a lot less trouble than some heath robinson homebuild. The cream of the crop is the honda 1kW so quiet but it's more than three times the cost of the one I use. Don't be tempted to buy more than 1 kW they are so much heavier on arms and petrol. Quote Link to comment Share on other sites More sharing options...
KingKade Posted August 31, 2015 Share Posted August 31, 2015 Posted by Donald Fry on 31/08/2015 17:21:37: ......"Of course a child on a generator bike, driven by bribe, or fear, has to be good for a 100 watts, and as they can be enclosed, you can lose the noise. Just a thought. Thats the funniest thing I've read on this forum today!!!! Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted August 31, 2015 Share Posted August 31, 2015 Graeme Do you know how much current the boat generators produce? They are designed to be just trickle chargers as they can be left running 24/7. In conditions you are likely to be flying in they don't produce a huge amount of power. Quote Link to comment Share on other sites More sharing options...
TheFlyingCrust Posted September 1, 2015 Share Posted September 1, 2015 Have a look here. Some good articles on building your own. If you use a brushless motor its Kv would have to be pretty low, I fear. You could use a large stepper motor. There's some plans around for them. Some experimenters have used small car alternators but the problem with them is they need a shaft speed upwards of 1000 rpm before they start generating. Best of luck Ian Quote Link to comment Share on other sites More sharing options...
adrian lawrence 1 Posted September 1, 2015 Share Posted September 1, 2015 Hi, apart from some of the limitations already mentioned I dont think that a brushless motor would work too well as a generator. A friend and I tried generating power with one some years ago and very little voltage and current was produced. We put this down to the amount of magnets on the rotor not giving enough variation in the magnetic field over the stator coils, and thus the lack of efficiency. We were going to remove alternative magnets to see if that gave better results, alas something that was abandoned due to other projects taking precedence. Adrian Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted September 1, 2015 Share Posted September 1, 2015 Much better off with solar, as has been mention imho. It doesn't have to be a sunny day to get a decent charge coming in, and to really get the benefit a wind generator needs to be raised up high, which is a real faff. I use two 90w panels on my motorhome - the 220Ah battery bank is fully charged by 11am, even in the winter. Edited By Andy Meade on 01/09/2015 09:09:47 Quote Link to comment Share on other sites More sharing options...
mightypeesh Posted September 1, 2015 Share Posted September 1, 2015 Maybe I am being too simplistic here - Would it not be more cost effective to use the hundreds of pounds required to get a system to charge the packs to just buy more packs that are charged before you go and use the car/leisure batterys for keeping the beer cold? Not reliant on the wind or sun either! ......Unless of course you use loads of packs in a day - which may be the case! Cheers, Simon Quote Link to comment Share on other sites More sharing options...
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