Homebrewed Electricity > Wind
Christmas Windmill Time
taylorp035:
This motor has been tested quite a few times with different methods. I dug up some data using a Bridgeport and a load cell + lever arm + optical tachometer from 2016. This was the lowest RPM it was tested at.
I figure I'm at about 1.6 ohms, which based on the old data means about 10.5 amps at 880 RPM (or so I think...). It lines up with the data I have from today's lathe test if you were to extrapolate it. The resistance was calculated and not measured for this chart.
Efficiency is going to probably be in the 30-50% range at such a low RPM and voltage now that I look at it. The goal of this isn't to make the most efficient windmill system, but to make the most power with a set of blades that are big enough to get the thing spinning without a hurricane force wind. I'm half tempted to give up the higher amps for something that starts up the easiest (8ft vs 6 ft). I also am thinking of making the blades extra wide and have no taper for better start up performance.
For fun, the peak efficiency of the motor was measured at about 3500 RPM pushing ~500 watts at 83% efficiency. It still was holding 80% at 1000 watts. I've seen 16+ amps at 125 volts dc (2 kw) of electrical power out of it and it probably has done more when I wasn't looking. 4000 RPM with (10) 300W light bulbs hooked up was pushing 19 amps at 91 volts (1729 watts). The poor motor was smoking after we completed a half hour of testing at 100 rpm increments in a 10hp CNC mill. It had been used to test Briggs and Stratton's for about 8 years after it being in my windmills for 2 years. It was rated at 4,000 RPM, but I know it's seen at least 5,500 when we had a really hot 68 cc engine hooked up to it at WOT.
SparWeb:
OK
Don't make 8-foot blades turn at 800 RPM with just 200W mechanically holding them back - things will fly apart!
Your generator can do much more than just charge a few 18650 batteries. It's got the guts to drive much more than that.
Unfortunately, what I see in the numbers you're writing is that it runs at speeds almost 10x faster than you'd want the wind turbine to run.
You want to see peak efficiency at 350 RPM, not 3500. :(
taylorp035:
Time for an update. I worked on the storage side for this project. I spent about 4 days tearing apart the 60v 6ah Dewalt pack, cleaned up the cells, ranked the cells by their capacities and then made a battery holder for it all. Soon I'll get 4 more 2600 mah cells from a friend. If it all works well and I want more, I can make another tray and triple my capacity for ~$60 worth of cells (~62 ah).
I CNC cut some battery holders and made some rubber backed aluminum tabs to contact all the cells at once. Then I tried it out on the lathe with the treadmill motor afterwards. The cells really hold the voltage well as I was hoping and it did 6.4 amps at 4.14 volts at ~600 rpm. Again, it will be a hair better once I don't have high resistance jumper leads in the system and a volt meter.
I ordered two cheap Chinese 10A 1S battery management units and a 40A 3S BMS once I'm ready to consume the power. I'll make my 3S 6P battery holder while I wait for them to travel on the slow boat over here. I've been recently busy fighting my 4S 12ah LiFe battery in my 1999 BMW M3 that I'm using instead of the ~60 lbs piece of lead that was in it. I've been running it for 6 months and ~10k miles with a 100ma balancer permanently hooked to it, but after flattening the battery for the 5th time, I realized that some cells were over charged and others had almost no charge... it's been quite the project to get it properly working and probably deserves a thread since it's a bit different.
Some pictures:
SparWeb:
--- Quote --- I've been recently busy fighting my 4S 12ah LiFe battery in my 1999 BMW M3 that I'm using instead of the ~60 lbs piece of lead that was in it. I've been running it for 6 months and ~10k miles with a 100ma balancer permanently hooked to it, but after flattening the battery for the 5th time, I realized that some cells were over charged and others had almost no charge... it's been quite the project to get it properly working and probably deserves a thread since it's a bit different.
--- End quote ---
Please!
Bruce S:
--- Quote from: SparWeb on January 07, 2020, 01:01:18 AM ---
--- Quote --- I've been recently busy fighting my 4S 12ah LiFe battery in my 1999 BMW M3 that I'm using instead of the ~60 lbs piece of lead that was in it. I've been running it for 6 months and ~10k miles with a 100ma balancer permanently hooked to it, but after flattening the battery for the 5th time, I realized that some cells were over charged and others had almost no charge... it's been quite the project to get it properly working and probably deserves a thread since it's a bit different.
--- End quote ---
Please!
--- End quote ---
What SparWeb said! :)
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