Lithium ion cell voltage not going up after 3.8V

[tmhobadcap]

I got a chromebook with battery problem. It was charging when plugged in. But the indicator just showed that the battery was below 10% no matter how long it was plugged in. I took the battery pack out. There are two cells in series. Each cell had a voltage of about 3.7V. I charged one of them with a lithium cell charger. I can see current going into the cell at about 500mA. After several hours, the voltage was just about 3.8V. I charged it again manually by connecting 4.2V to it from a power supply and set the maximum current to 500mA. I can see about 100mA going into the cell. But the voltage was still 3.8V after several hours. I have never come across such situation. Can somebody tell me what is wrong with the cell?

[sam_sam_sam]

This is a common problem with pouch battery I personally do not like them because most if not all are made in China done with my ranting about Chinese made batteries

With that said if you had a pouch battery has been on the charger for more than 3 hours and the voltage has not gone with 500 milliamperes or or become swollen or is battery warm to the touch if so STOP charging it and do not keep charging or using it has internal issues also if the pouch battery is swollen also stop using it ( let the battery sit for several days and see if the voltage is go lower as time goes on )

If you are going to charge pouch battery or 18650 li-ion battery type cells you do not know the health of you really need to consider buying a SkyRc b6 version 2 with temperature sensor accessories one note if you are wanting to do more than one battery cell and are you are not going to use the balancing function you will need to do a firmware update but I caution you about doing a firmware update on this device it is NOT straight forward and when first start installing the update you will think it not doing anything be very cautious about turning it off and turning it back on you will brick it and you will not be able to use it again ( SkyRc b6 version 2 )
and use the temperature sensor on the battery that you are testing set the temperature sensor setting to no higher than 35*C
The SkyRc MC3000 is easier to use but I would highly recommend that you either hook it up to a computer or a tablet it is a lot easier to set the parameters you can use the buttons on the device but it is time consuming one feature that it has primitive graphical charts but if want more detail then you have to go to something like a EBC-A10H it is a bit more expensive but you have a lot more control over the parameters and a much better graphical chart for changing and discharging curves

I have a SkyRc MC3000 and a SkyRc b6 version 2 and a more advanced battery testing machine that does not have a temperature sensor capably and when I get battery cells that are questionable and the website seller that I buy from are very up front about questionable battery I will first put one of the battery tester that has a temperature sensor and use it

There are two known issues with li-ion battery cells one is called self discharge syndrome and the other one is heater cell syndrome both of them you need to be aware of and test for them

The self discharge syndrome can be tested as follows charge the battery fully if you can then let it sit untouched for 30 days make sure that you note the voltage and the voltage after 30 days that if there is any change more than 0.500 volts you have a self ( there is quicker test but I have not done enough testing or research on how accurate the results are but you have to have the more advanced battery testing machine and what you do is if the lowest recommended voltage is is 2.8 or 2.5 volts take it down to 2.00 volts and see how high the voltage goes beyond or come very close 3.00 volts if the voltage stays closer to 2.5 to 2.8 volts or if you keep seeing the voltage drop over several days one note you have to use the monitor mode to do this test ) then there might be an issue with discharge syndrome is it dangerous to keep using no but I caution you that as the battery cell degradation will get worse and you could end up with heater cell syndrome and this is the reason to stop using them when it gets to this point

I hope this helps you answer the questions that you were asking about your situation with your battery cells on your Chromebook

Just be careful handling pouch battery cells do NOT use metal sharp objects anywhere near them because they will burst in flames and it is not easy to put it out it has happened to me twice since I have been messing around with this battery types of cells

[stj]

not all lithiums are 4.2v - it's a shame the cell has no markings

[tmhobadcap]

This is a common problem with pouch battery I personally do not like them because most if not all are made in China done with my ranting about Chinese made batteries

With that said if you had a pouch battery has been on the charger for more than 3 hours and the voltage has not gone with 500 milliamperes or or become swollen or is battery warm to the touch if so STOP charging it and do not keep charging or using it has internal issues also if the pouch battery is swollen also stop using it ( let the battery sit for several days and see if the voltage is go lower as time goes on )

If you are going to charge pouch battery or 18650 li-ion battery type cells you do not know the health of you really need to consider buying a SkyRc b6 version 2 with temperature sensor accessories one note if you are wanting to do more than one battery cell and are you are not going to use the balancing function you will need to do a firmware update but I caution you about doing a firmware update on this device it is NOT straight forward and when first start installing the update you will think it not doing anything be very cautious about turning it off and turning it back on you will brick it and you will not be able to use it again ( SkyRc b6 version 2 )
and use the temperature sensor on the battery that you are testing set the temperature sensor setting to no higher than 35*C
The SkyRc MC3000 is easier to use but I would highly recommend that you either hook it up to a computer or a tablet it is a lot easier to set the parameters you can use the buttons on the device but it is time consuming one feature that it has primitive graphical charts but if want more detail then you have to go to something like a EBC-A10H it is a bit more expensive but you have a lot more control over the parameters and a much better graphical chart for changing and discharging curves

I have a SkyRc MC3000 and a SkyRc b6 version 2 and a more advanced battery testing machine that does not have a temperature sensor capably and when I get battery cells that are questionable and the website seller that I buy from are very up front about questionable battery I will first put one of the battery tester that has a temperature sensor and use it

There are two known issues with li-ion battery cells one is called self discharge syndrome and the other one is heater cell syndrome both of them you need to be aware of and test for them

The self discharge syndrome can be tested as follows charge the battery fully if you can then let it sit untouched for 30 days make sure that you note the voltage and the voltage after 30 days that if there is any change more than 0.500 volts you have a self ( there is quicker test but I have not done enough testing or research on how accurate the results are but you have to have the more advanced battery testing machine and what you do is if the lowest recommended voltage is is 2.8 or 2.5 volts take it down to 2.00 volts and see how high the voltage goes beyond or come very close 3.00 volts if the voltage stays closer to 2.5 to 2.8 volts or if you keep seeing the voltage drop over several days one note you have to use the monitor mode to do this test ) then there might be an issue with discharge syndrome is it dangerous to keep using no but I caution you that as the battery cell degradation will get worse and you could end up with heater cell syndrome and this is the reason to stop using them when it gets to this point

I hope this helps you answer the questions that you were asking about your situation with your battery cells on your Chromebook

Just be careful handling pouch battery cells do NOT use metal sharp objects anywhere near them because they will burst in flames and it is not easy to put it out it has happened to me twice since I have been messing around with this battery types of cells

Thanks for your comments. But they did not answer my question.
My cells are not swollen. When charging, they were cool.

[tmhobadcap]

not all lithiums are 4.2v - it's a shame the cell has no markings

Thanks for your comment.
Sorry, I did not post the outer packing of the battery pack. Also, there is markings on the cell, but I just do not know what it means. Here they are.
The markings show 7.7V which I think should be the nominal voltage. Then the maximum or full voltage for each cell should be 4.2V. Did I make a mistake?

[sam_sam_sam]

I just do not know what it means. Here they are.
The markings show 7.7V which I think should be the nominal voltage.
Then the maximum or full voltage for each cell should be 4.2V. Did I make a mistake?

I personally do not understand this either because I am wondering if it is a Lipo 4 type battery then would make sense in respect of maximum voltage
what is the Chromebook's voltage going to battery terminals because 7.7 volts would make sense now if the voltage is 8.4 volts going to battery cells then would say that the battery battery pack has some type of issue

[tmhobadcap]

I personally do not understand this either because I am wondering if it is a Lipo 4 type battery then would make sense in respect of maximum voltage
what is the Chromebook's voltage going to battery terminals because 7.7 volts would make sense now if the voltage is 8.4 volts going to battery cells then would say that the battery battery pack has some type of issue

According to the label on the chrome book, the input voltage is 19.5V.

[sam_sam_sam]

No I am talking about the power cable going to the battery pack

[tmhobadcap]

No I am talking about the power cable going to the battery pack

Sorry, I do not have the original power adaptor.

[sam_sam_sam]

The only way to determine what type of battery this is you have to know what voltage is sent to the battery pack from the Chromebook power supply being sent to the battery pack because if it is a Lipo 4 type the maximum voltage is supposed to be 3.5 to 3.6 and li-ion type is 4.2 to 4.35 but the higher voltage value is a special version of the regular li-ion battery the 7.7 is what is making think that it is a Lipo type battery and if you put to much voltage to them you could have thermal run away because they are not designed for this high of voltage

Most of the time the voltage from the switching power to a computer is a lot higher than what is required by the battery pack because it has a BMS that controls the voltage and current that goes to the battery pack and most types of tablets as well