Output Coils

[Jimboot]

If you are suggesting that you should connect a voltmeter to the unloaded discharging coil you should never do this.  The current source output from the discharging coil will generate an unknown high voltage that may fry the voltmeter and/or give the experimenter a very nasty shock.

Interesting. i've done it thousands of times and never had this problem. Lucky I guess.

[Farmhand]

It all depends on the amount of potential energy stored in the magnetic field of the coil. If the stored potential energy is not much then no problem. But if you have a large coil with low resistance and high inductance which is holding a lot of potential energy in the magnetic field then problems can arise. The amount of energy is a big factor when safety is concerned.

A bad battery with an internal fault could be caused to explode if the high voltage produced by the high resistance causes an internal spark in the battery and if there is Hydrogen and oxygen present inside it.

An exploding lead acid battery is a very bad situation even when there is no one present everything the sulfuric acid gets splashed on becomes degraded or destroyed. If one was standing looking at a battery when it exploded then heaven help them.

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Personally I don't allow much more than 24 volts at the battery terminals, with a switched coil charger (not regulated) this can be controlled by the applied voltage to the circuit or by reducing the pulse width for the charging of the coil.

Desulfation takes time to happen and it takes time to reverse.

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Micro processor control and custom charging algorithms can be fun, controlling the pulse width and limiting the voltage at the battery terminals is just a picaxe program away.

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[Farmhand]

Interesting. i've done it thousands of times and never had this problem. Lucky I guess.

If the circuit did not destroy itself then the energy was fairly low I would say. Multimeters have MOhm resistance on voltage setting.

and the higher the voltage gets the narrower the discharge spike is as well, (in the time domain).

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[nathanj99]

The answer to your question is that the output that charges the charge battery is not a voltage source, it's a current source.  A discharging coil is a current source.  The output voltage of the coil is primarily determined by the voltage of the charging battery itself.  The voltage going into the charging battery is not determined by the coil.

You should try Googling "What is a current source?" and "Voltage source vs. current source."

If you can understand the concept of a current source and how it works then you will be ahead of 98% of all Bedini motor enthusiasts.  I can't explain why, but literally there are Bedini motor enthusiasts that play with their Bedini motors for years with no understanding whatsoever that when the charging battery is being charged it's being charged by a discharging inductor that is a current source.

wow, I have been reading up about current sources. I think I kind of get it. But if one uses the output combined with a capacitor to power a light bulb rather than charge a battery, what would the voltage source be? or am I simply not understanding it?

Thanks for all the info everyone, its all very interesting .

[MileHigh]

Interesting. i've done it thousands of times and never had this problem. Lucky I guess.

Why have you been doing this test?  I am curious.  You state "Hook one up to your output before you hook it to the battery just to see what it is. I had some output coils that were pushing out 1kv on a simple pulse motor."

So is your test to verify that the coil is capable of generating high voltage?  If that's the case then you are not really measuring anything significant.

I think a typical multimeter has a high voltage scale that goes up to 2000 volts.  I don't know what voltage it takes to blow the input for a digital multimeter but let's say it's 5000 volts for the sake of argument.  For an analog multimeter you can fry the winding in the needle deflection mechanism.  Let's say for the sake of argument it would take 5000 volts in this case also.

Let's assume that both digital and analog multimeters have a one megaohm input resistance.

Let's suppose that you hook the multimeter in series with a discharging coil, and the initial discharging current from the coil is one ampere.  So that means you have a one-ampere current source that wants to pump that current into a one megaohm resistance.  That means that the theoretical maximum voltage output from the coil (for a fraction of a second) is one million volts.

MileHigh