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Latitude 7480 battery showing wrong percentage, stays at 0 for 1 hour.
hello, i bought new dell battery, 4cell 60wh f3ygt. when i bought it, it held no charge, so i had to charge it from 0. first time when i charged it, i didnt give it enough time to fully charge (for the sake of good calibration), because i didnt know that batteries need calibration on first use, so battery managment system got wrong value of my full charge capacity. it says 36 to 33 wh fcc, when estimated is 60wh. i know this battery is new and it has bms bugged because it holds 5-6 hours while watching video on full brightness and max power settings. when it starts discharging, it need 3 hours to get to 7 percent, then it is stuck on 7 percent for 1 hour, after that it goes to 0 in 15 mins and stops there for about 1.5 hour before it shuts down. how can i fix this behaviour.
ejn63
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July 8th, 2024 14:54
It's not uncommon for a battery to need a few charge-discharge cycles to reach its maximum capacity, but having started at just over 40% and only reaching 60% after a week means there's something seriously wrong with the battery. Either a cell isn't holding charge or all of them are weak.
The battery needs to be replaced -- contact your seller if they provided a warranty on the battery.
There's also a date code on a Dell battery inside the alphanumeric string of the Dell part number (usually starts with CN, KR or JP). Post that and someone can tell you when it was made -- this system is about seven years old, and if the battery is as well, used or not -- it will never reach its design capacity.
ejn63
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July 9th, 2024 10:55
That battery was made in 2017, so it's pretty old -- it's not uncommon for an aging battery to behave erratically.
ejn63
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July 6th, 2024 22:11
The battery should not have arrived flat if it was relatively new (1 year old or less). Have the seller replace it under whatever warranty they provide.
Dimavar123
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July 8th, 2024 11:02
@ejn63 even if it was not completely new and it was used only once for test purposes, it still lasts as long as any new battery would, only problem is calibration. the fact that its health went from f to good and full charge capacity increased from 25 to 38, it means it has calibration issues which i dont know how to solve. charging and recharging seems to have some kind of effect but really small, i was thinking about resetting battery management system which is embedded in battery but i dont know how.
ejn63
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July 8th, 2024 11:52
Lithium batteries do not need calibration, and if the battery was left completely discharged for any length of time, one or more of the cells could be permanently reduced in capacity.
Yes, there is a logic board that manages the cells, but no -- it cannot be addressed by software.
Dimavar123
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July 8th, 2024 12:04
@ejn63 i have read in internet that sometimes bms reads wrong values which results in showing wrong battery percentage and thats why bms itself needs to calibrate, specially when installing new batteries. my battery capacity has not reduced, it is fine, only problem is that battery percentage it is showing, and full charge capacity it thinks battery has, is wrong.
ejn63
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July 8th, 2024 14:08
If you're using a Windows system, run
powercfg
At a command prompt with admin privilege. It will show you the design and current charge capacity of the battery.
Dimavar123
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July 8th, 2024 14:42
@ejn63 current charge capacity was 25wh before i started charging cycles and it slowly increased to 36wh in 7 days. design is 60wh.
Dimavar123
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July 9th, 2024 10:33
@ejn63 this is my battery which shows wrong percentage but lasts as good as new (8 hours under normal conditions).
Dimavar123
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July 9th, 2024 13:43
@ejn63 thank you, i also just noticed in batteryinfoview app that my battery has voltage drops, which results in rising currents and i read somewhere that it indicates that cells are imbalanced (one of them might be damaged). calibration has reached 39wh already and keeps increasing tho. i understand that battery is old and it might be problematic but ill see where calibration takes me. thank you for help.
Dimavar123
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July 16th, 2024 09:33
@ejn63 hello how do you determine when it was made, so that i can also know in future and let them send pictures before i actually buy.