huge dc voltage drop

Thread Starter

clark.kent156

Joined Aug 17, 2019
47
Hi. I could use a little help. I have a homemade stator, the AC runs thru rectifiers, and produces average 5.5vdc at output. The output is then connected to a boost module, to produce 12vdc at output. The stator diagram and pic of the boost module are attached. The thing is, whenever a load is connected, in this case I'm testing with an led removed from a flashlight, the reading drops dramatically, like down to 6v. I'm not sure what is causing this. How do I get a steady 12v output with a load?
 

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MrSoftware

Joined Oct 29, 2013
2,056
The load is drawing more current than the rest of the circuit can provide. Check the voltage at the output of the stator to see if it's the stator that can't keep up, or if it's the boost circuit that can't keep up. Check the current your boost circuit is rated for and compare against your load.
 

Thread Starter

clark.kent156

Joined Aug 17, 2019
47
The load is drawing more current than the rest of the circuit can provide. Check the voltage at the output of the stator to see if it's the stator that can't keep up, or if it's the boost circuit that can't keep up. Check the current your boost circuit is rated for and compare against your load.
Thanks. The stator without booster and no load, is 5v. booster added, 13v, attach load, then drops back almost to stator output. i will check out the comparison of the booster against the load.
 

AlbertHall

Joined Jun 4, 2014
12,187
Was 12V applied to this LED in the flashlight?
Is there a resistor in series with the LED? If not it will draw a vast current.
 

AlbertHall

Joined Jun 4, 2014
12,187
It depends what value resistor you use but at least measuring the voltage across the resistor and knowing the value of the resistor you can be sure how much current is being drawn.
You can slso do this connecting the reisistor only to a resistor.
 

Tonyr1084

Joined Sep 24, 2015
7,190
A mistake I used to make was thinking I could boost the voltage and still have the same power (wattage). 5 volts at 2 amps can be boosted to 10 volts at 1 amp. Why? Because 5 volts times 2 amps equals 10 watts. And 10 volts times 1 amp also equals 10 watts. Of course I'm speaking in "Ideal" components. An ideal component has absolute conductivity and does not waste any power by changing anything into parasitic heat. In the real world wires don't conduct 100%. They get warm, they get hot. Their resistance goes up. More power (remember voltage times amperage equals wattage, which is also referred to as power) - but more power is wasted as heat. Until I learned that power factor can not be changed without changing both the voltage AND the amperage I would have wondered why something that looked like it would work on paper didn't work in the real world.

If your stator can only produce 200 mA (milli-amps) at 5 volts then at 12 volts it will produce less than 83 mA. Less because of losses in efficiency. The numbers: 5V x 0.2A = 1W. 1W ÷ 12V = 0.08333•••A. If your flashlight is drawing more than 83mA then the voltage WILL be pulled down. Depending on how many amps it draws will determine how far down the voltage falls. Now - I'm just making up numbers for the sake of helping you understand how and why you can't get the amperage (or wattage) you need if the root supply (the stator) is not capable of producing that much power.
 

SamR

Joined Mar 19, 2019
4,483
Typically you do NOT want to use a 1/4W resistor for an unknown Vs. Go for 100s kΩ or even MΩs and at least 1W. You want to limit the I across it. YMMV
 

Thread Starter

clark.kent156

Joined Aug 17, 2019
47
There 18 homemade coils. Each coil has 725 turns of wire at 28awg. of course, there is an array of magnets rotating super close to the coils to induce current/volts. if this helps.
 

Tonyr1084

Joined Sep 24, 2015
7,190
Thanks @clark.kent156 but that's not enough information. Size, power and spacing of the magnets are a small part of the equation - an equation I don't know how to solve. Core type (steel and its composition are factors). Laminated steel or powdered ferrite cores change the power factor. Diameter of the coil array, speed of rotation of the armature also factor in.

What you CAN do is take a single coil output and put a 100 ohm 1 watt resistor across its terminals and measure the voltage across that resistor when the armature is spinning at a given rate. Measure the voltage with and without the resistor. Once you know the voltage produced and the voltage dropped across the resistor you can calculate the current (amperage) produced by a single coil. If you have 8 coils then multiply your findings by 8. Then you have a pretty good idea what to expect from the alternator (which is what you've built).
 

MisterBill2

Joined Jan 23, 2018
13,698
An LED is a VERY non-linear load. Above some voltage where it starts to light up rather brightly the current will rise very rapidly. So it is not the best load to check with.

And the circuit does not look like it generates a lot of power. The brutal reality is that with any circuit you will not get out more power than you put in. That is really very fundamental.
 

Thread Starter

clark.kent156

Joined Aug 17, 2019
47
An LED is a VERY non-linear load. Above some voltage where it starts to light up rather brightly the current will rise very rapidly. So it is not the best load to check with.

And the circuit does not look like it generates a lot of power. The brutal reality is that with any circuit you will not get out more power than you put in. That is really very fundamental.
i'd like to get 12v and enough current to connect to an inverter.
 

Tonyr1084

Joined Sep 24, 2015
7,190
I'm looking at your drawing of the coils. Any two coils, let's focus on the two coils at positions 12 oClock and 1 oClock. Each coil is wound in the same direction (according to your drawing). Coils #12 & #1 are wired in such a way that - to me - it appears they are bucking each other. No where in your diagram is the neutral connected to anything except all other coils. IF your coil assembly IS wired as shown, you might be generating a voltage on one coil and opposing it on the very next. I'm certainly no motor - or generator expert, but it appears you might want to use opposing coils (such as #12 and #6) instead of using adjacent coils. OR each coil should have its own rectifier.
 

MisterBill2

Joined Jan 23, 2018
13,698
That stator setup is not very efficient and it is not likely that you can get much more power than you are getting from it, so an alternative device is a better choice. What I see in that drawing is a setup where only one coil at a time is producing any energy, and that is quite limiting itself.
The use of the energy created has not been mentioned, other than lighting an LED. An explanation of what the energy would be used for will be very useful.
In addition, if the result is AC power, then it will be far more efficient to use a transformer to raise the voltage. One additional thing is that to get electrical energy out you must supply mechanical energy. So to get more energy more effort is required. You will do far better copying the designs of existing generators or alternators.
 
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