Help identify the discrete component in this battery pack











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18
down vote

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I am rebuilding a NiMH battery pack for a RF remote control device which can be recharged by plugging the device in.



The battery pack is connected with three wires:




  • black to the negative

  • red to the positive

  • BLUE through a mysterious discrete component to the negative


battery pack



The component in line with the blue wire looks a bit like a glass-body diode but my multimeter cannot measure a diode voltage. (It measures infinity, not zero, if this helps.)



However, I can measure about 11.5 kOhm across the component in both directions.



Can anybody enlighten me, what this component is likely to be? I would like to verify that the component is still functional because it is unclear whether or not the device still charges properly.










share|improve this question




















  • 1




    remotely related: Why are there 3 pins on some batteries?
    – Nick Alexeev
    Nov 20 at 1:00















up vote
18
down vote

favorite












I am rebuilding a NiMH battery pack for a RF remote control device which can be recharged by plugging the device in.



The battery pack is connected with three wires:




  • black to the negative

  • red to the positive

  • BLUE through a mysterious discrete component to the negative


battery pack



The component in line with the blue wire looks a bit like a glass-body diode but my multimeter cannot measure a diode voltage. (It measures infinity, not zero, if this helps.)



However, I can measure about 11.5 kOhm across the component in both directions.



Can anybody enlighten me, what this component is likely to be? I would like to verify that the component is still functional because it is unclear whether or not the device still charges properly.










share|improve this question




















  • 1




    remotely related: Why are there 3 pins on some batteries?
    – Nick Alexeev
    Nov 20 at 1:00













up vote
18
down vote

favorite









up vote
18
down vote

favorite











I am rebuilding a NiMH battery pack for a RF remote control device which can be recharged by plugging the device in.



The battery pack is connected with three wires:




  • black to the negative

  • red to the positive

  • BLUE through a mysterious discrete component to the negative


battery pack



The component in line with the blue wire looks a bit like a glass-body diode but my multimeter cannot measure a diode voltage. (It measures infinity, not zero, if this helps.)



However, I can measure about 11.5 kOhm across the component in both directions.



Can anybody enlighten me, what this component is likely to be? I would like to verify that the component is still functional because it is unclear whether or not the device still charges properly.










share|improve this question















I am rebuilding a NiMH battery pack for a RF remote control device which can be recharged by plugging the device in.



The battery pack is connected with three wires:




  • black to the negative

  • red to the positive

  • BLUE through a mysterious discrete component to the negative


battery pack



The component in line with the blue wire looks a bit like a glass-body diode but my multimeter cannot measure a diode voltage. (It measures infinity, not zero, if this helps.)



However, I can measure about 11.5 kOhm across the component in both directions.



Can anybody enlighten me, what this component is likely to be? I would like to verify that the component is still functional because it is unclear whether or not the device still charges properly.







batteries identification






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 19 at 10:22

























asked Nov 19 at 10:01









ARF

2,77033155




2,77033155








  • 1




    remotely related: Why are there 3 pins on some batteries?
    – Nick Alexeev
    Nov 20 at 1:00














  • 1




    remotely related: Why are there 3 pins on some batteries?
    – Nick Alexeev
    Nov 20 at 1:00








1




1




remotely related: Why are there 3 pins on some batteries?
– Nick Alexeev
Nov 20 at 1:00




remotely related: Why are there 3 pins on some batteries?
– Nick Alexeev
Nov 20 at 1:00










2 Answers
2






active

oldest

votes

















up vote
35
down vote



accepted










Its a thermistor like this (photo from internet, not spam related):



Photo from internet



This kind of resistor depends on the temperature of both batteries.



EDIT: In this photo, is a Negative Temperature Coefficient. There are also Positive Temperature Coefficient resistors. The main difference between them is how the resistor decreases or increases when the temperature grows, respectively.



That's a cheap component and a cheaper way to determine when both batteries are charged up.



When a NiMH is almost charged, its temperature starts to grow. If you measure the temperature based on a voltage divider into a DAC, you can measure the temperature and, therefore, activate the charge or deactivate it.



EDIT: The thermistor must be very close to the batteries to read a correct value, so that's why this discrete component is located close to the batteries.



The temperature based graph to read when stop charging the battery is like this:



Photo from internet



Related: Voltage input for charging NiMH Batteries



If you can measure the temperature, you can check when it's charged up.






share|improve this answer



















  • 3




    +1 your answer is much better than mine.
    – dim
    Nov 19 at 10:12


















up vote
10
down vote













It is a thermistor. This senses the battery temperature, so the charger can know when something goes wrong.



Measuring it likely won't tell you if the battery pack is still working correctly, though.






share|improve this answer

















  • 1




    Of course, that makes perfect sense. I should have thought of that. Easy to verify and not very likely to break. - Many thanks!
    – ARF
    Nov 19 at 10:11











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2 Answers
2






active

oldest

votes








2 Answers
2






active

oldest

votes









active

oldest

votes






active

oldest

votes








up vote
35
down vote



accepted










Its a thermistor like this (photo from internet, not spam related):



Photo from internet



This kind of resistor depends on the temperature of both batteries.



EDIT: In this photo, is a Negative Temperature Coefficient. There are also Positive Temperature Coefficient resistors. The main difference between them is how the resistor decreases or increases when the temperature grows, respectively.



That's a cheap component and a cheaper way to determine when both batteries are charged up.



When a NiMH is almost charged, its temperature starts to grow. If you measure the temperature based on a voltage divider into a DAC, you can measure the temperature and, therefore, activate the charge or deactivate it.



EDIT: The thermistor must be very close to the batteries to read a correct value, so that's why this discrete component is located close to the batteries.



The temperature based graph to read when stop charging the battery is like this:



Photo from internet



Related: Voltage input for charging NiMH Batteries



If you can measure the temperature, you can check when it's charged up.






share|improve this answer



















  • 3




    +1 your answer is much better than mine.
    – dim
    Nov 19 at 10:12















up vote
35
down vote



accepted










Its a thermistor like this (photo from internet, not spam related):



Photo from internet



This kind of resistor depends on the temperature of both batteries.



EDIT: In this photo, is a Negative Temperature Coefficient. There are also Positive Temperature Coefficient resistors. The main difference between them is how the resistor decreases or increases when the temperature grows, respectively.



That's a cheap component and a cheaper way to determine when both batteries are charged up.



When a NiMH is almost charged, its temperature starts to grow. If you measure the temperature based on a voltage divider into a DAC, you can measure the temperature and, therefore, activate the charge or deactivate it.



EDIT: The thermistor must be very close to the batteries to read a correct value, so that's why this discrete component is located close to the batteries.



The temperature based graph to read when stop charging the battery is like this:



Photo from internet



Related: Voltage input for charging NiMH Batteries



If you can measure the temperature, you can check when it's charged up.






share|improve this answer



















  • 3




    +1 your answer is much better than mine.
    – dim
    Nov 19 at 10:12













up vote
35
down vote



accepted







up vote
35
down vote



accepted






Its a thermistor like this (photo from internet, not spam related):



Photo from internet



This kind of resistor depends on the temperature of both batteries.



EDIT: In this photo, is a Negative Temperature Coefficient. There are also Positive Temperature Coefficient resistors. The main difference between them is how the resistor decreases or increases when the temperature grows, respectively.



That's a cheap component and a cheaper way to determine when both batteries are charged up.



When a NiMH is almost charged, its temperature starts to grow. If you measure the temperature based on a voltage divider into a DAC, you can measure the temperature and, therefore, activate the charge or deactivate it.



EDIT: The thermistor must be very close to the batteries to read a correct value, so that's why this discrete component is located close to the batteries.



The temperature based graph to read when stop charging the battery is like this:



Photo from internet



Related: Voltage input for charging NiMH Batteries



If you can measure the temperature, you can check when it's charged up.






share|improve this answer














Its a thermistor like this (photo from internet, not spam related):



Photo from internet



This kind of resistor depends on the temperature of both batteries.



EDIT: In this photo, is a Negative Temperature Coefficient. There are also Positive Temperature Coefficient resistors. The main difference between them is how the resistor decreases or increases when the temperature grows, respectively.



That's a cheap component and a cheaper way to determine when both batteries are charged up.



When a NiMH is almost charged, its temperature starts to grow. If you measure the temperature based on a voltage divider into a DAC, you can measure the temperature and, therefore, activate the charge or deactivate it.



EDIT: The thermistor must be very close to the batteries to read a correct value, so that's why this discrete component is located close to the batteries.



The temperature based graph to read when stop charging the battery is like this:



Photo from internet



Related: Voltage input for charging NiMH Batteries



If you can measure the temperature, you can check when it's charged up.







share|improve this answer














share|improve this answer



share|improve this answer








edited Nov 19 at 13:45

























answered Nov 19 at 10:09









José Manuel Ramos

56129




56129








  • 3




    +1 your answer is much better than mine.
    – dim
    Nov 19 at 10:12














  • 3




    +1 your answer is much better than mine.
    – dim
    Nov 19 at 10:12








3




3




+1 your answer is much better than mine.
– dim
Nov 19 at 10:12




+1 your answer is much better than mine.
– dim
Nov 19 at 10:12












up vote
10
down vote













It is a thermistor. This senses the battery temperature, so the charger can know when something goes wrong.



Measuring it likely won't tell you if the battery pack is still working correctly, though.






share|improve this answer

















  • 1




    Of course, that makes perfect sense. I should have thought of that. Easy to verify and not very likely to break. - Many thanks!
    – ARF
    Nov 19 at 10:11















up vote
10
down vote













It is a thermistor. This senses the battery temperature, so the charger can know when something goes wrong.



Measuring it likely won't tell you if the battery pack is still working correctly, though.






share|improve this answer

















  • 1




    Of course, that makes perfect sense. I should have thought of that. Easy to verify and not very likely to break. - Many thanks!
    – ARF
    Nov 19 at 10:11













up vote
10
down vote










up vote
10
down vote









It is a thermistor. This senses the battery temperature, so the charger can know when something goes wrong.



Measuring it likely won't tell you if the battery pack is still working correctly, though.






share|improve this answer












It is a thermistor. This senses the battery temperature, so the charger can know when something goes wrong.



Measuring it likely won't tell you if the battery pack is still working correctly, though.







share|improve this answer












share|improve this answer



share|improve this answer










answered Nov 19 at 10:08









dim

13k22367




13k22367








  • 1




    Of course, that makes perfect sense. I should have thought of that. Easy to verify and not very likely to break. - Many thanks!
    – ARF
    Nov 19 at 10:11














  • 1




    Of course, that makes perfect sense. I should have thought of that. Easy to verify and not very likely to break. - Many thanks!
    – ARF
    Nov 19 at 10:11








1




1




Of course, that makes perfect sense. I should have thought of that. Easy to verify and not very likely to break. - Many thanks!
– ARF
Nov 19 at 10:11




Of course, that makes perfect sense. I should have thought of that. Easy to verify and not very likely to break. - Many thanks!
– ARF
Nov 19 at 10:11


















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