Newbies > Newbies
Rookie learning through DIY, prototyping alternator
Mary B:
Small nicks could cause shorts, check each coil with an ohm meter to make sure they are identical.
Wired in series like that you get high voltage/low current. Wired in star(most common) you get lower voltage closer to battery voltage and higher current. Either can work if you use MPPT(Maximum Power Point Tracking) especially with the first.
Wiring diagram for the coils
This gives you 3 phase AC, you need a 3 phase rectifier to change it to DC so you can use it.
SimonMester:
--- Quote from: Mary B on June 05, 2023, 12:17:49 PM ---Small nicks could cause shorts, check each coil with an ohm meter to make sure they are identical.
Wired in series like that you get high voltage/low current. Wired in star(most common) you get lower voltage closer to battery voltage and higher current. Either can work if you use MPPT(Maximum Power Point Tracking) especially with the first.
Wiring diagram for the coils
This gives you 3 phase AC, you need a 3 phase rectifier to change it to DC so you can use it.
--- End quote ---
I have seen these diagrams, but I wasn't looking to do 3 phase, I was just looking to do single phase first, and understand what I'm doing wrong. I like to move from simple to more complex designs as I learn more. :)
I'm sorry what do you mean? I can measure resistance with my multimeter, but what would I see if the coils are okay, and what would I see if they weren't? Not sure how you mean I should check the coils.
Bruce S:
That depends on your meter.
IF it's the old reliable swing pointer type and "good" coil will show a dead short, unless you have one that can read down into the single ohms range. And broken coil will show nothing, it'll be as if the leads aren't touching anything.
Newer digital type for a "good" coil will show something real low even when you switch it to lowest ohm setting, broken one will show all zeros like the leads aren't touching anything. Give us the size of the wire mm or awg and length, we can let you know what the Ohm (resistance) should be.
Bruce S
electrondady1:
those are nice magnets, but the spacing between them is too wide .
first, they should be sitting on an iron core .
the magnets should be alternating polarity.
the width between the magnets should be the same as the width of the magnet.
the hole in the center of the coil should be about the same width as the magnet or slightly wider.
the width of the legs of your coils should be the same as the width of the magnet.
you want to have one leg of a coil crossing a negative pole and the other leg crossing a positive pole.
as the mechanism rotates the polarity changes and electricity is generated in your coil.
it is the change of polarity that makes the alternating current
SimonMester:
Thank you for that! I have gone through them on the lowest Ohm setting (which is 200 on my multimeter)
It just showed fairly random jumpy numbers from single to double digits on all of them.
As per above the current wire I am using is 0.85mm enameled copper wire.
Some news in the meantime!
I have liberated the coils from their resin backing. Was hard since I used a tough, flexible resin (which I instantly regret now :D)
I have been testing the coils with my rotor, and the numbers are really low, compared to the small ceramic magnet I have. I removed the rotor rod, which is mild steel, in case that messes with the magnets somehow, but no change.
I have considered maybe I ruined the NdFeB magnets with heat, as they are sensitive, but I tested the same NdFeB magnets (ones I have never used) and they induce the same low current. The magnets are strong, doesn't feel like there should be anything wrong with them, and yet the ceramics are seemingly better?
For context, each NdFeB is 100mm x 10mm x 10mm, and the ceramic magnet is 48 x 22 x 10 mm. Not on a rotor, just passing it above the coil, at the same speed and distance it produces about the same current.
Does this mean the limiting factor is not the magnet but the wire? Or is it do with something else?
Also, in any of these cases, it still seems to apply that the faster the magnets move the weaker current I get. Is this just me misunderstanding the readings, or some actual physical effect in the coils, like parasitic capacitance?
Thank you. ^^
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