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impedance meter to test car battery

Started by Jamie M December 29, 2019
Whoey Louie <trader4@optonline.net> wrote in
news:aaea4b2f-92b2-4172-8b91-a0c0fbb61a06@googlegroups.com: 

> On Tuesday, December 31, 2019 at 7:33:42 PM UTC-5, Rick C wrote: >> On Tuesday, December 31, 2019 at 12:23:49 PM UTC-5, Whoey Louie >> wrote: >> > On Monday, December 30, 2019 at 5:25:55 PM UTC-5, Rick C wrote: >> > > On Monday, December 30, 2019 at 3:01:02 PM UTC-5, Jasen Betts >> > > wrote: >> > > > On 2019-12-30, Rick C <gnuarm.deletethisbit@gmail.com> >> > > > wrote: >> > > > >> > >> > > > >> > How much is a supercapacitor that will have a useful >> > > > >> > capacity at that voltage? >> > > > > >> > > > > Not sure how the battery and supercap will interact. On >> > > > > discharge, >> > > > >the cap will supply current at a decreasing voltage, so >> > > > >the battery won't supply much current until the voltage >> > > > >starts to drop. As the battery voltage starts to drop the >> > > > >battery will drain down. Once the cranking stops and the >> > > > >alternator starts to charge, the cap will still >> > > > >be at a low voltage and will suck up all the current. Do >> > > > >you know if the electronics in the alternator will prevent >> > > > >damage by charging a very high current into a low voltage? >> > > > > Will the current be limited? Will the alternator not try >> > > > >to raise the voltage immediately? I don't really know how >> > > > >the electronics in the alternator is designed. >> > > > >> > > > You seem to have forgotten that altenators are current >> > > > sources, incapable of producing more than the rated >> > > > current. >> > > >> > > If it is a current source, then it can be equated to a >> > > voltage source with a high value series resistor. >> > >> > Say what? The current would then decline rapidly with any >> > applied load. That isn't a current source. >> >> Ok, if you say so Always Wrong. >> >> -- > > > And what exactly was that about? A current source most > definitely does not look anything like a voltage source with a > high value resistor is series. It's not clear exactly what the > poster who said alternators are a current source meant. If he > meant they behave similar to an ideal current source, that's wrong > too. They look more like a voltage source, with the alternator/VR > trying to maintain a constant voltage. A current source puts out a > fixed current, regardless of the voltage or load. > > > >
An alternator is typically a fixed voltage device. It is a fixed voltage POWER SOURCE. Which is to say that it IS indeed a current source, all the while refusing to generate a voltage higher than its designed setpoint. Constant voltage, current varies with load. So if it is below spec rpm, it will not behave properly and will appear to act differently than ideal doctrine.
On Wednesday, January 1, 2020 at 3:31:17 PM UTC-5, Jasen Betts wrote:
> On 2020-01-01, Whoey Louie <trader4@optonline.net> wrote: > > > And what exactly was that about? A current source most definitely does not > > look anything like a voltage source with a high value resistor is series. > > It's not clear exactly what the poster who said alternators are a > > current source meant. If he meant they behave similar to an ideal > > current source, that's wrong too. They look more like a voltage source, > > with the alternator/VR trying to maintain a constant voltage. A current > > source puts out a fixed current, regardless of the voltage or load. > > The regulator limits the output, but we were taling about recovery.
IDK what you're talking about. I was responding to the posts that claimed an auto alternator behaves like a current source. It doesn't, it behaves similar to a voltage source. A current source would be trying to maintain a fixed current. An alternator/VR maintains a fixed VOLTAGE.
> when the voltage is low it's operating at full power, in that region > it's a current source.
Nonsense. It's no more a current source when delivering 100 amps than it is when it's delivering 5.
> > Once the regulator kicks in
The VR is always operating. it starts to pretend to be a voltage source
> and the battery, which is a voltage source, does a fine job of covering > up its flaws. > > -- > Jasen.
On Wednesday, January 1, 2020 at 3:50:55 PM UTC-5, Rick C wrote:
> On Wednesday, January 1, 2020 at 9:53:51 AM UTC-5, Whoey Louie wrote: > > On Tuesday, December 31, 2019 at 7:33:42 PM UTC-5, Rick C wrote: > > > On Tuesday, December 31, 2019 at 12:23:49 PM UTC-5, Whoey Louie wrote: > > > > On Monday, December 30, 2019 at 5:25:55 PM UTC-5, Rick C wrote: > > > > > > > > > > If it is a current source, then it can be equated to a voltage source with a high value series resistor. > > > > > > > > Say what? The current would then decline rapidly with any applied load. > > > > That isn't a current source. > > > > > > Ok, if you say so Always Wrong. > > > > And what exactly was that about? A current source most definitely does not > > look anything like a voltage source with a high value resistor is series. > > Ok, so now rather than admit you were wrong and move on from there, you are retrenching by trying to ignore what you posted. > > You are so much like the Always Wrong who you love to scorn. > > -- > > Rick C. > > --- Get 1,000 miles of free Supercharging > --- Tesla referral code - https://ts.la/richard11209
Heh genius. You claim that an auto alternator behaves like a current source with a high value resistor. I say you're full of baloney, it behaves like a VOLTAGE SOURCE. I can give you the model using a voltage source. Take an ideal voltage source of value 15V in series with a 0.025 resistor. With a load of 1 amp, the alternator puts out ~15V. With a load of 100 amps, it puts out 12.5V. Now provide us with the values for your current source and high value resistor that you claim model it.
On Wednesday, January 1, 2020 at 5:48:03 PM UTC-5, DecadentLinux...@decadence.org wrote:
> Whoey Louie <trader4@optonline.net> wrote in > news:aaea4b2f-92b2-4172-8b91-a0c0fbb61a06@googlegroups.com: > > > On Tuesday, December 31, 2019 at 7:33:42 PM UTC-5, Rick C wrote: > >> On Tuesday, December 31, 2019 at 12:23:49 PM UTC-5, Whoey Louie > >> wrote: > >> > On Monday, December 30, 2019 at 5:25:55 PM UTC-5, Rick C wrote: > >> > > On Monday, December 30, 2019 at 3:01:02 PM UTC-5, Jasen Betts > >> > > wrote: > >> > > > On 2019-12-30, Rick C <gnuarm.deletethisbit@gmail.com> > >> > > > wrote: > >> > > > >> > > >> > > > >> > How much is a supercapacitor that will have a useful > >> > > > >> > capacity at that voltage? > >> > > > > > >> > > > > Not sure how the battery and supercap will interact. On > >> > > > > discharge, > >> > > > >the cap will supply current at a decreasing voltage, so > >> > > > >the battery won't supply much current until the voltage > >> > > > >starts to drop. As the battery voltage starts to drop the > >> > > > >battery will drain down. Once the cranking stops and the > >> > > > >alternator starts to charge, the cap will still > >> > > > >be at a low voltage and will suck up all the current. Do > >> > > > >you know if the electronics in the alternator will prevent > >> > > > >damage by charging a very high current into a low voltage? > >> > > > > Will the current be limited? Will the alternator not try > >> > > > >to raise the voltage immediately? I don't really know how > >> > > > >the electronics in the alternator is designed. > >> > > > > >> > > > You seem to have forgotten that altenators are current > >> > > > sources, incapable of producing more than the rated > >> > > > current. > >> > > > >> > > If it is a current source, then it can be equated to a > >> > > voltage source with a high value series resistor. > >> > > >> > Say what? The current would then decline rapidly with any > >> > applied load. That isn't a current source. > >> > >> Ok, if you say so Always Wrong. > >> > >> -- > > > > > > And what exactly was that about? A current source most > > definitely does not look anything like a voltage source with a > > high value resistor is series. It's not clear exactly what the > > poster who said alternators are a current source meant. If he > > meant they behave similar to an ideal current source, that's wrong > > too. They look more like a voltage source, with the alternator/VR > > trying to maintain a constant voltage. A current source puts out a > > fixed current, regardless of the voltage or load. > > > > > > > > > > An alternator is typically a fixed voltage device.
Agreed. It is a fixed
> voltage POWER SOURCE. Which is to say that it IS indeed a current > source,
Well, like I already said if you want to talk about that definition of "current source", then so too is a battery, a cap, or a lightning bolt. But when someone brings up something being a current source in the context of electrical engineering they usually mean that whatever they are talking about behaves like an ideal current source, which we use in EE, which is source that maintains a constant CURRENT, regardless of what load is on it. That isn't an alternator, which behaves like a voltage source. You can model it with an ideal voltage source of about 15V and a low value resistor in series of about 0.025 ohms. all the while refusing to generate a voltage higher than its
> designed setpoint. Constant voltage, current varies with load.
Agree.
On Wednesday, January 1, 2020 at 4:31:10 PM UTC-5, Jasen Betts wrote:
> On 2020-01-01, Whoey Louie <trader4@optonline.net> wrote: > > On Wednesday, January 1, 2020 at 3:01:09 PM UTC-5, Jasen Betts wrote: > >> On 2019-12-30, Rick C <gnuarm.deletethisbit@gmail.com> wrote: > >> > On Monday, December 30, 2019 at 3:01:02 PM UTC-5, Jasen Betts wrote: > >> >> On 2019-12-30, Rick C <gnuarm.deletethisbit@gmail.com> wrote: > >> >> >> > > >> > >> >> You seem to have forgotten that altenators are current sources, > >> >> incapable of producing more than the rated current. > >> > > >> > If it is a current source, then it can be equated to a voltage > >> > source with a high value series resistor. > >> > >> I didn't say it was a Norton current source. > > > > A Norton equivalent is not a voltage source in series with a resistor. > > It's a current source in PARALLEL with a resistor. > > Damn, I always get those two confused. I didn't say it was a Thevenin > source either. > > > And an auto alternator > > doesn't behave like a current source in any way shape or form. One clue > > is that they use VOLTAGE regulators, which make it appear like an ideal > > voltage source, that tries to keep the VOLTAGE with a small range. > > Tries and sometimes fails.
Give me a break. I assume we are talking about a working alternator operating within it's normal range. See also "load dump"
> > > A current source would seek to put out a constant current, the resulting > > voltage, be damned. > > And that's what happens in a load dump. > > > If it's a current source putting out 1A, and the > > load was 12 ohms, it would be 12V, if the load was 1200 ohms it would be > > 1200 volts. Capiche? > > You don't.
Oh yes I do. I'm waiting for Rick to give us the values for his ideal current source and the high value series resistor that model how an alternator behaves.
> > > Doesn't work well for a car. > > like I've been saying all along. > > -- > Jasen.
On Wednesday, January 1, 2020 at 5:01:13 PM UTC-5, Jasen Betts wrote:
> On 2020-01-01, Rick C <gnuarm.deletethisbit@gmail.com> wrote: > > On Wednesday, January 1, 2020 at 3:01:09 PM UTC-5, Jasen Betts wrote: > >> On 2019-12-30, Rick C <gnuarm.deletethisbit@gmail.com> wrote: > >> > On Monday, December 30, 2019 at 3:01:02 PM UTC-5, Jasen Betts wrote: > >> >> On 2019-12-30, Rick C <gnuarm.deletethisbit@gmail.com> wrote: > >> >> >> > > >> > >> >> You seem to have forgotten that altenators are current sources, > >> >> incapable of producing more than the rated current. > >> > > >> > If it is a current source, then it can be equated to a voltage > >> > source with a high value series resistor. > >> > >> I didn't say it was a Norton current source. > > > > You seem to not understand the term. What exactly do you mean by > > "current source"???? Norton equated a current source to other > > circuits. He didn't define or invent the current source. > > is it important what claims I did not make? I used the wrong term. > > >> > What would the open circuit voltage be? > >> > >> That depends on the engine speed and the strength of the field. > >> typically could be 80V. > >> > >> > What would the short circuit current be? > >> > >> That depends mostly on the magnetic field strength, which is controlled > >> by the armature current and has a hard limit when the rotor > >> saturates. > >> > >> When the stator current is high enough to cancel the magnetic field > >> that's your limit, more spin won't get you more current. > > > > So is the alternator a current source or not? > > It's more like a current source than like a voltage source, in that > when open circuit it produces harmful voltages, but when shorted nothing > bad happens. > > -- > Jasen.
Try that and see. And since when are we talking about disconnected alternators? shorted alternators? The discussion was how a working, normally operating alternator behaves in a car.
On Wednesday, January 1, 2020 at 5:44:33 PM UTC-5, Rick C wrote:
> On Wednesday, January 1, 2020 at 5:01:13 PM UTC-5, Jasen Betts wrote: > > On 2020-01-01, Rick C <gnuarm.deletethisbit@gmail.com> wrote: > > > On Wednesday, January 1, 2020 at 3:01:09 PM UTC-5, Jasen Betts wrote: > > >> On 2019-12-30, Rick C <gnuarm.deletethisbit@gmail.com> wrote: > > >> > On Monday, December 30, 2019 at 3:01:02 PM UTC-5, Jasen Betts wrote: > > >> >> On 2019-12-30, Rick C <gnuarm.deletethisbit@gmail.com> wrote: > > >> >> >> > > > >> > > >> >> You seem to have forgotten that altenators are current sources, > > >> >> incapable of producing more than the rated current. > > >> > > > >> > If it is a current source, then it can be equated to a voltage > > >> > source with a high value series resistor. > > >> > > >> I didn't say it was a Norton current source. > > > > > > You seem to not understand the term. What exactly do you mean by > > > "current source"???? Norton equated a current source to other > > > circuits. He didn't define or invent the current source. > > > > is it important what claims I did not make? I used the wrong term. > > Doesn't matter. Both Norton and Thevenin are wrong the way you want to use them. There is no such thing as a "Thevenin current source". Thevenin just said you could equate any given DC circuit to a voltage source and a resistor. Norton said you could equate any given DC circuit to a current source and a resistor. > > You seem to want to make a distinction between a current source and the Thevenin equivalent.
Since you know so much, give us the values for the current source and high value resistor that you claim model an alternator...... I can give you the VOLTAGE source model, take a 15V ideal voltage source in series with a 0.025 ohm resistor. So, what value ideal current source and what high value resistor do we use with your model?
> > > > >> > What would the open circuit voltage be? > > >> > > >> That depends on the engine speed and the strength of the field. > > >> typically could be 80V. > > >> > > >> > What would the short circuit current be? > > >> > > >> That depends mostly on the magnetic field strength, which is controlled > > >> by the armature current and has a hard limit when the rotor > > >> saturates. > > >> > > >> When the stator current is high enough to cancel the magnetic field > > >> that's your limit, more spin won't get you more current. > > > > > > So is the alternator a current source or not? > > > > It's more like a current source than like a voltage source, in that > > when open circuit it produces harmful voltages, but when shorted nothing > > bad happens. > > I don't know that. I was simply saying that combining a rather large cap with the battery an alternator may produce excessive currents. If nothing else it may blow a fuse. I believe that is what happened in my truck when something shorted to ground. A wire fried burning up it's insulation but the repair shop never could explain what shorted. Meanwhile the 160 amp fuse blew. I think this could happen with the super cap as well. > > -- > > Rick C. > > -+- Get 1,000 miles of free Supercharging > -+- Tesla referral code - https://ts.la/richard11209
On Wednesday, January 1, 2020 at 7:13:42 PM UTC-5, Whoey Louie wrote:
> On Wednesday, January 1, 2020 at 3:50:55 PM UTC-5, Rick C wrote: > > On Wednesday, January 1, 2020 at 9:53:51 AM UTC-5, Whoey Louie wrote: > > > On Tuesday, December 31, 2019 at 7:33:42 PM UTC-5, Rick C wrote: > > > > On Tuesday, December 31, 2019 at 12:23:49 PM UTC-5, Whoey Louie wrote: > > > > > On Monday, December 30, 2019 at 5:25:55 PM UTC-5, Rick C wrote: > > > > > > > > > > > > If it is a current source, then it can be equated to a voltage source with a high value series resistor. > > > > > > > > > > Say what? The current would then decline rapidly with any applied load. > > > > > That isn't a current source. > > > > > > > > Ok, if you say so Always Wrong. > > > > > > And what exactly was that about? A current source most definitely does not > > > look anything like a voltage source with a high value resistor is series. > > > > Ok, so now rather than admit you were wrong and move on from there, you are retrenching by trying to ignore what you posted. > > > > You are so much like the Always Wrong who you love to scorn. > > > > -- > > > > Rick C. > > > > --- Get 1,000 miles of free Supercharging > > --- Tesla referral code - https://ts.la/richard11209 > > > Heh genius. You claim that an auto alternator behaves like a current > source with a high value resistor. I say you're full of baloney, it > behaves like a VOLTAGE SOURCE. I can give you the model using a voltage > source. Take an ideal voltage source of value 15V in series with a > 0.025 resistor. With a load of 1 amp, the alternator puts out ~15V. > With a load of 100 amps, it puts out 12.5V. > > Now provide us with the values for your current source and high value > resistor that you claim model it.
You need to read the posts you respond to as well as your own. I never made the claim you say I did. You meanwhile incorrectly said a current source is not equivalent to a voltage source in series with a high value resistance. Just read the posts quoted above. It's that simple, Always Wrong. -- Rick C. --+ Get 1,000 miles of free Supercharging --+ Tesla referral code - https://ts.la/richard11209
On Wednesday, January 1, 2020 at 7:01:47 PM UTC-5, Whoey Louie wrote:
> On Wednesday, January 1, 2020 at 3:31:17 PM UTC-5, Jasen Betts wrote: > > On 2020-01-01, Whoey Louie <trader4@optonline.net> wrote: > > > > > And what exactly was that about? A current source most definitely does not > > > look anything like a voltage source with a high value resistor is series. > > > It's not clear exactly what the poster who said alternators are a > > > current source meant. If he meant they behave similar to an ideal > > > current source, that's wrong too. They look more like a voltage source, > > > with the alternator/VR trying to maintain a constant voltage. A current > > > source puts out a fixed current, regardless of the voltage or load. > > > > The regulator limits the output, but we were taling about recovery. > > IDK what you're talking about. I was responding to the posts that > claimed an auto alternator behaves like a current source. It doesn't, > it behaves similar to a voltage source. A current source would be > trying to maintain a fixed current. An alternator/VR maintains a > fixed VOLTAGE.
It is a current LIMITED power source that is voltage regulated. The current limiting comes from the internal resistance of the Alternator's windings. Compare it to a lab grade bench power supply. You can set the output voltage, and it will go into current limiting to protect itself.
On 1.1.20 22:09, Whoey Louie wrote:
> On Wednesday, January 1, 2020 at 2:27:01 PM UTC-5, Tauno Voipio wrote: >> On 1.1.20 16:53, Whoey Louie wrote: >>> On Tuesday, December 31, 2019 at 7:33:42 PM UTC-5, Rick C wrote: >>>> On Tuesday, December 31, 2019 at 12:23:49 PM UTC-5, Whoey Louie wrote: >>>>> On Monday, December 30, 2019 at 5:25:55 PM UTC-5, Rick C wrote: >>>>>> On Monday, December 30, 2019 at 3:01:02 PM UTC-5, Jasen Betts wrote: >>>>>>> On 2019-12-30, Rick C <gnuarm.deletethisbit@gmail.com> wrote: >>>>>>>>>> >>>>>>>>>> How much is a supercapacitor that will have a useful capacity at that voltage? >>>>>>>> >>>>>>>> Not sure how the battery and supercap will interact. On discharge, >>>>>>>> the cap will supply current at a decreasing voltage, so the battery >>>>>>>> won't supply much current until the voltage starts to drop. As the >>>>>>>> battery voltage starts to drop the battery will drain down. Once the >>>>>>>> cranking stops and the alternator starts to charge, the cap will still >>>>>>>> be at a low voltage and will suck up all the current. Do you know if >>>>>>>> the electronics in the alternator will prevent damage by charging a >>>>>>>> very high current into a low voltage? Will the current be limited? >>>>>>>> Will the alternator not try to raise the voltage immediately? I don't >>>>>>>> really know how the electronics in the alternator is designed. >>>>>>> >>>>>>> You seem to have forgotten that altenators are current sources, >>>>>>> incapable of producing more than the rated current. >>>>>> >>>>>> If it is a current source, then it can be equated to a voltage source with a high value series resistor. >>>>> >>>>> Say what? The current would then decline rapidly with any applied load. >>>>> That isn't a current source. >>>> >>>> Ok, if you say so Always Wrong. >>>> >>>> -- >>> >>> >>> And what exactly was that about? A current source most definitely does not >>> look anything like a voltage source with a high value resistor is series. >>> It's not clear exactly what the poster who said alternators are a >>> current source meant. If he meant they behave similar to an ideal >>> current source, that's wrong too. They look more like a voltage source, >>> with the alternator/VR trying to maintain a constant voltage. A current >>> source puts out a fixed current, regardless of the voltage or load. >> >> >> You are mistaken. Please get an elementary textbook on basic electronic >> theory and look up de Thevenin's and Norton's theorems. >> >> -- >> >> -TV > > I'm totally familiar with Thevenin and Norton equivalents. Neither has > anything to do with some power source behaving like a *current source*. > Why would an alternator or any electric power source be considered > a "current source", when it can be modeled using either voltage sources > or current sources? Hello? An alternator is only a current source > in the same sense that a battery, a capacitor, or a static spark is > a "current source". They all deliver current, sure. But so, what? > When one starts talking about something being a "current source' in > the context of it's output characteristics, that implies that they are > saying it's behaving like an ideal current source or similar to one. > Which is one that > delivers a constant current regardless of load. That most certainly > is NOT a car alternator. Cars have VOLTAGE regulators, which is a > clue. They behave more like an ideal voltage source, seeking to > keep the VOLTAGE within a target rangd. Nor is it like a voltage > source in series with a > high value resistor, which the village idiot put forth. That is beyond > stupid. So sad that we have people here commenting on electronics, > when they don't even have a grasp of the very basics of electricity 101.
For one last time: The theorems prove that a voltage source with an output series impedance is indistinguishable from an equivalent current source with an output parallel admittance. All real voltage sources have some output impedance and all real current sources have some output admittance. A question: We have two black boxes, one containing a voltage source and the other containing a current source. The boxes cannot be opened. When measured from the output terminals, the open-circuit voltage is 1V and the short-circuit current is 1A. Which box contains which source? -- -TV