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| Samsung phones are charging batteries with an ugly pattern? |
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| jjman:
Hi Guys, Looks like there is a very ugly charging pattern on all samsung galaxy phones I could get hold of. Can you please check these results and tell me if there is some obvious problem with my conclusions? So here is the graph (see the attachments): time: The time since the first measurement interval agilent current: is a charging current measured on the USB port using Agilent U1272A + U1177A phone current: is the charging current reported by the current sensor on the phone From the chart it looks like when the battery is fully charged instead of detaching it and running straight on power from the AC (like a normal notebook) the phone starts running off the battery then discharges it a bit (the battery gauge on the phone shows always 100%) and then recharges it again. So at the end it looks like the battery management system is doing microcycles right in one of worst areas possible: the 90-100% capacity area.That should promote the forming of the solid electrolyte interphase hense speeding up battery degradation (as we essentially have the battery operated on the top voltage which increases the oxidation of cathode from the electrolyte and it makes the SEI layer thicker) . Now why is that a problem? Well … when usually most people charge their phones? During the night … hence looks like a very nice planned obsolescence ‘feature’? P.s. Here is my setup if you would like to reproduce it: 1. Pc is pulling data from agilent via BT with SPP profile (essentially using the FETC? command) 2. Pc is pulling data from app on the samsung (that is again exposed with SPP and responds to the same FETC? command). The app uses the /sys/class/power_supply/battery/batt_current_ua_now kernel driver to read the current sensor from the BMS. 3. There is some slight desync (in the ms range) as both sources of information does not respond simultaneously. CSV files with the results are attached here. Best Regards Ivan |
| amyk:
Have you tried phones of any other manufacturer? I suspect this could be due to a "serial" power management system (charger<>battery<>discharger) and done to save cost... |
| jjman:
It looks like it is not cost related, it looks like deliberate battery degradation ... and now that you mentioned cost here is example from a cheap Xiaomi (redmi note 2). Once charged it does not use the battery. My interpretation of the results: As the phone is cheap it does not have a current sensor inside (do not be fooled by the data in the /sys/class/power_supply/battery/curent_now kernel driver - it is 0 for discahrging, 515 on usb charger and 1468 for AC charger). So one can see that once charged it continues working in the 200mA-500mA current draw. When video is played (to check the charging behavior) once can see that the phone just increases the consumption from the charger (a solid 600mA) once the video playback finishes the current consumption goes to the old state which is observed when the phone is in standby and fully charged. The important thing is that during the video playback no "charging" pattern is seen. And when the phone is fully charged and in standby current continuously flows in to the device which for me is an indication that the battery is not used. Attached are some sample files. |
| Mechatrommer:
--- Quote from: jjman on February 02, 2019, 08:22:18 pm ---It looks like it is not cost related, it looks like deliberate battery degradation --- End quote --- really? any reference to this claim? one of our galaxy's (kzoom) battery hasnt been changed since longer than 5 years now iirc. how long should we expect a lion battery lasts on constant use? 10 years? 20 years? and what profit will they make if we buy 3rd party battery as replacement? |
| Yansi:
Complete stupid and dumb ignorance, if not anything else. |
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