On Saturday, December 11, 2021 at 11:30:50 AM UTC+11, David Eather wrote:> On 10/12/2021 9:50 pm, Sylvia Else wrote: > > Anyone aware of such a thing? > > > > Clearly, one can achieve that just by putting a thermistor in series > > with an ordinary resistor, but my UPS seems to contain a single > > component that behaves that way - perhaps less than 1% at 20 Celcius - > > it's in the circuit that controls the battery charging float voltage. > > > > Did they perhaps exist 20 years ago (when my UPS was made), for some > > reason? > > lead acid batteries are temperature sensitive when rechargingAll batteries - as electrochemical devices - are temperature sensitive https://en.wikipedia.org/wiki/Gibbs_free_energy If you scroll down to "In electrochemical thermodynamics" you will get to the Nernst Equation https://en.wikipedia.org/wiki/Nernst_equation which can be seen as the Gibbs Free energy equation for electrochemical systems - curiously, Nernst formulated it in 1888 some twelves years after Gibbs had published the more general formulation. Thermodynamics isn't easy to get your head around - even if you are as clever as Nernst, who eventually got a Nobel prize in 1920 for his work on the third law of thermodynamics. Once instilled, it does tend to stick - as an undergraduate in 1961 it took me a while to get my head around that particular bit of the chemistry course. -- Bil Sloman, Sydney
Low coefficient NTC resistors?
Started by ●December 10, 2021
Reply by ●December 10, 20212021-12-10
Reply by ●December 10, 20212021-12-10
On 11-Dec-21 11:30 am, David Eather wrote:> On 10/12/2021 9:50 pm, Sylvia Else wrote: >> Anyone aware of such a thing? >> >> Clearly, one can achieve that just by putting a thermistor in series >> with an ordinary resistor, but my UPS seems to contain a single >> component that behaves that way - perhaps less than 1% at 20 Celcius - >> it's in the circuit that controls the battery charging float voltage. >> >> Did they perhaps exist 20 years ago (when my UPS was made), for some >> reason? >> >> Sylvia > > lead acid batteries are temperature sensitive when rechargingYes, this is presumably the reason for the NTC resistor in the charging circuit. But if it has a typical thermistor characteristic, then in this particular implementation, the compensation will be out by a factor of ten, which is probably worse than no compensation at all. I may have to remove it from the circuit to better characterise it. Sylvia.
Reply by ●December 10, 20212021-12-10
Stupider than Anybody Else wrote: ========================== >>> >> Clearly, one can achieve that just by putting a thermistor in series > >> with an ordinary resistor, but my UPS seems to contain a single > >> component that behaves that way - perhaps less than 1% at 20 Celcius - > >> it's in the circuit that controls the battery charging float voltage. > >> > >> Did they perhaps exist 20 years ago (when my UPS was made), for some > >> reason? > >> > >> Sylvia > > > > lead acid batteries are temperature sensitive when recharging > > Yes, this is presumably the reason for the NTC resistor in the charging > circuit. But if it has a typical thermistor characteristic, then in this > particular implementation, the compensation will be out by a factor of > ten, which is probably worse than no compensation at all. > > I may have to remove it from the circuit to better characterise it. >** WTF are you on about ???? Themistors ( NTC or PTC) do not look like regular resistors. Are you claiming KNOW there is a resistor ( banded or not ) that has a very large neg tempco in your UPS? Or just making wild, idiot guesses as bloody usual. ...... Phil
Reply by ●December 10, 20212021-12-10
On Saturday, December 11, 2021 at 12:02:59 PM UTC+11, Sylvia Else wrote:> On 11-Dec-21 11:30 am, David Eather wrote: > > On 10/12/2021 9:50 pm, Sylvia Else wrote: > >> Anyone aware of such a thing? > >> > >> Clearly, one can achieve that just by putting a thermistor in series > >> with an ordinary resistor, but my UPS seems to contain a single > >> component that behaves that way - perhaps less than 1% at 20 Celcius - > >> it's in the circuit that controls the battery charging float voltage. > >> > >> Did they perhaps exist 20 years ago (when my UPS was made), for some > >> reason? > >> > >> Sylvia > > > > lead acid batteries are temperature sensitive when recharging > Yes, this is presumably the reason for the NTC resistor in the charging > circuit. But if it has a typical thermistor characteristic, then in this > particular implementation, the compensation will be out by a factor of > ten, which is probably worse than no compensation at all. > > I may have to remove it from the circuit to better characterise it.If it is a carbon composition or carbon film resistor it won't look much like a thermistor https://eepower.com/resistor-guide/resistor-materials/carbon-film-resistor/# The range from -2.5×10-4 Ω/°C to -8×10-4 Ω/°C is quite a bit lower -two orders of magnitude - than the typical NTC thermistor at - -3 to -6x10-2. It would still be a pretty horrible temperature sensor. The original designers may have been a bit optimistic about the reproducibility and stability of the part they put in. Carbon film resistors might not have looked quite as cheap and nasty twenty years ago - they did to me back then, but then there were engineers around who saw them as cheap, rather than nasty, and there may still be some who think that way. -- Bill Sloman, Sydney
Reply by ●December 10, 20212021-12-10
On 11-Dec-21 12:10 pm, Phil Allison wrote:> Stupider than Anybody Else wrote: > ========================== > >> >>>> Clearly, one can achieve that just by putting a thermistor in series >>>> with an ordinary resistor, but my UPS seems to contain a single >>>> component that behaves that way - perhaps less than 1% at 20 Celcius - >>>> it's in the circuit that controls the battery charging float voltage. >>>> >>>> Did they perhaps exist 20 years ago (when my UPS was made), for some >>>> reason? >>>> >>>> Sylvia >>> >>> lead acid batteries are temperature sensitive when recharging >> >> Yes, this is presumably the reason for the NTC resistor in the charging >> circuit. But if it has a typical thermistor characteristic, then in this >> particular implementation, the compensation will be out by a factor of >> ten, which is probably worse than no compensation at all. >> >> I may have to remove it from the circuit to better characterise it. >> > > ** WTF are you on about ???? > > Themistors ( NTC or PTC) do not look like regular resistors. > > Are you claiming KNOW there is a resistor ( banded or not ) that has a very large neg tempco in your UPS? > > Or just making wild, idiot guesses as bloody usual. > >Where did I say it looked like an ordinary resistor? It doesn't. Amongst other things, it's labelled on the board as NTC001. It also clearly has a negative temperature coefficient, as demonstrated by the use of a multimeter and a hair dryer (yes, of course I have a heat gun, but the hair dryer seemed less likely to damage anything). It's in series with a fixed resistor and a trimmer, which together with a resistor from the output to the adjustment pin of an LM317T, define the voltage on that pin, and thus sets the charging voltage for the batteries. Is more evidence required? Sylvia.
Reply by ●December 10, 20212021-12-10
Stupider than Anybody Else wrote: ==========================> > > >>>> Clearly, one can achieve that just by putting a thermistor in series > >>>> with an ordinary resistor, but my UPS seems to contain a single > >>>> component that behaves that way - perhaps less than 1% at 20 Celcius - > >>>> it's in the circuit that controls the battery charging float voltage. > >>>> > >>>> Did they perhaps exist 20 years ago (when my UPS was made), for some > >>>> reason? > >>>> > >>>> Sylvia > >>> > >>> lead acid batteries are temperature sensitive when recharging > >> > >> Yes, this is presumably the reason for the NTC resistor in the charging > >> circuit. But if it has a typical thermistor characteristic, then in this > >> particular implementation, the compensation will be out by a factor of > >> ten, which is probably worse than no compensation at all. > >> > >> I may have to remove it from the circuit to better characterise it. > >> > > > > ** WTF are you on about ???? > > > > Themistors ( NTC or PTC) do not look like regular resistors. > > > > Are you claiming KNOW there is a resistor ( banded or not ) that has a very large neg tempco in your UPS? > > > > Or just making wild, idiot guesses as bloody usual. > > > > > Where did I say it looked like an ordinary resistor?** In the heading - fuckwit.> Amongst other things, it's labelled on the board as NTC001. >** What other crucial facts have you omitted ??> It also clearly has a negative temperature coefficient, as demonstrated > by the use of a multimeter and a hair dryer (yes, of course I have a > heat gun, but the hair dryer seemed less likely to damage anything).** OK, so that is one of them.> It's in series with a fixed resistor and a trimmer,** Why did you LIE and hide info in your first post ?> which together with > a resistor from the output to the adjustment pin of an LM317T, define > the voltage on that pin, and thus sets the charging voltage for the > batteries.** Charging and float voltages are not the same.> Is more evidence required?** None more needed to prove what a time wasting troll you are. ..... Phil
Reply by ●December 10, 20212021-12-10
On Friday, December 10, 2021 at 6:44:44 AM UTC-8, lang...@fonz.dk wrote:> fredag den 10. december 2021 kl. 12.50.41 UTC+1 skrev Sylvia Else: > > Anyone aware of such a thing? > > > > Clearly, one can achieve that just by putting a thermistor in series > > with an ordinary resistor, but ...> PT1000/PT100 is ~0.4%/COh, that's just about true for all classical metals; getting a non-PTAT (proportional to absolute temperature) resistor is a notable materials-science achievement. At 20 C, proportional to absolute temperature means about 0.0034 per kelvin; for copper, resistance goes 0.00386, for tungsten 0.0045, for aluminum 0.00429, for platinum 0.0039 ... The impure (alloyed) metals used for low tempco have very non-ideal metallic nature.
Reply by ●December 10, 20212021-12-10
The biggest Fuckwit on Usenet posts as whit3rd ====================================> > > PT1000/PT100 is ~0.4%/C > > Oh, that's just about true for all classical metals; getting a non-PTAT (proportional > to absolute temperature) resistor is a notable materials-science achievement. > > At 20 C, proportional to absolute temperature means about 0.0034 per kelvin; for > copper, resistance goes 0.00386, for tungsten 0.0045, for aluminum 0.00429, > for platinum 0.0039 ... > >The impure (alloyed) metals used for low tempco have very non-ideal metallic nature. >** " very non- ideal metallic nature" ??????? Could you please be bit more ambiguous ?? Cos some fuckheads here will imagine it makes sense. ...... Phil
Reply by ●December 10, 20212021-12-10
On Saturday, December 11, 2021 at 1:14:23 PM UTC+11, palli...@gmail.com wrote:> The biggest Fuckwit on Usenet posts as whit3rd > ==================================== > > > > > PT1000/PT100 is ~0.4%/C > > > > Oh, that's just about true for all classical metals; getting a non-PTAT (proportional > > to absolute temperature) resistor is a notable materials-science achievement. > > > > At 20 C, proportional to absolute temperature means about 0.0034 per kelvin; for > > copper, resistance goes 0.00386, for tungsten 0.0045, for aluminum 0.00429, > > for platinum 0.0039 ... > > > >The impure (alloyed) metals used for low tempco have very non-ideal metallic nature. > > > ** " very non- ideal metallic nature" ??????? > > Could you please be bit more ambiguous ?? > > Cos some fuckheads here will imagine it makes sense.Back when I was in paid work we got a marketing talk from Vishay on their very low temperature coefficient resistors which could get below +/-5ppm per degree Celcius, if you were willing to buy their most expensive parts (which we were, if not all that often). They not only mucked about with the composition of the materials they laid down in their thin films, but they also figured in temperature generated strain by laying down material with one cofficient of thermal expansion on a substrate with a a different one. This is a longer way of saying that they got non-ideal behaviour. I can see whit3rd might have wanted to avoid testing your attention span (which isn't all that long). -- Bill Sloman, Sydney
Reply by ●December 10, 20212021-12-10
IEEE Bill ....@ieee.org wrote: ===========================> > The biggest Fuckwit on Usenet posts as whit3rd > > ==================================== > > > > > > > PT1000/PT100 is ~0.4%/C > > > > > > Oh, that's just about true for all classical metals; getting a non-PTAT (proportional > > > to absolute temperature) resistor is a notable materials-science achievement. > > > > > > At 20 C, proportional to absolute temperature means about 0.0034 per kelvin; for > > > copper, resistance goes 0.00386, for tungsten 0.0045, for aluminum 0.00429, > > > for platinum 0.0039 ... > > > > > >The impure (alloyed) metals used for low tempco have very non-ideal metallic nature. > > > > > ** " very non- ideal metallic nature" ??????? > > > > Could you please be bit more ambiguous ?? > > > > Cos some fuckheads here will imagine it makes sense.> > They not only mucked about with the composition of the materials they laid down in their thin films, > but they also figured in temperature generated strain by laying down material with one cofficient > of thermal expansion on a substrate with a a different one. > This is a longer way of saying that they got non-ideal behaviour.** The witless moron posted about PURE METALS & low tempco metal alloys. You bullshitting, ridiculous ARSEHOLE !!! ..... Phil
