Question on battery cycle life of cell phones before they lose performance. - Page 1
Forum section: electronics / beginners

author: epigramx
author_rank: Regular Contributor
timestamp: May 20, 2023, 01:01:18 pm
content: This is a very simple question but google results are contaminated by normies giving very contradicting answers between each other and therefore I can not trust them.Assuming that we have studies that conclude that "cell phone batteries should be kept charged between 20% and 80%",is it even better for battery life to keep the pnones always plugged-in or even worse?

author: Gyro
author_rank: Super Contributor
timestamp: May 20, 2023, 01:15:23 pm
content: Even worse.Unless your phone has some clever charge level limiting feature eg. 80%, or app (which require root access I think), the phone will maintain the charge level at near 100%, which significantly shortens their life.

author: Jwillis
author_rank: Super Contributor
timestamp: May 20, 2023, 01:26:33 pm
content: Depends on the type of battery.For batteries like Nickel cadmium (NiCad)and Nickle Metel Hydride (NiMHi) its best to discharge nearly completely to prevent memory effect. Complete discharge is not recommended.On lithium ion batteries The life cycle of a battery is greatly affected by the depth of discharge. So a battery that is discharged 20% between charges will have a longer over all life cycle than a battery that is discharged 80% between charges.

author: David Hess
author_rank: Super Contributor
timestamp: May 20, 2023, 02:29:41 pm
content: Lithium rechargeable cells also have a degradation mechanism which depends on a power function of the cell voltage, so maintaining charge at say 100% decreases the operating life several times over maintaining charge at 80%, independent of the number of charge cycles. Optimum is suppose to be 65% or something.I would love to do that on my cell phone but the AT&T firmware prevents limiting the cell charge stage, and AT&T blocks firmware updates on their unlocked phones. The law requires them to unlock their phones to use on other services, but does not prevent them from crippling them.

author: RoGeorge
author_rank: Super Contributor
timestamp: May 20, 2023, 02:42:51 pm
content: For Li-Ion, the lower the voltage, the better. If kept at 4.2V, it will bulge (or at least some of mine did so after I've left them sitting fully charged (in a plastic ziplock bag) for a year. Though, under 2.5...3V, also not good, the battery will tend to form metal bridges inside.It's a compromise between how much energy is needed vs how often to recharge. Some Li-Ion datasheets specify the long term storage charge (about 70% or so, certainly NOT fully charged), or else the battery will get permanent damage. Same, some datasheets specify the shelf first charge at (about 30% or so of the nominal capacity), so the cells won't degrade while the phone is waiting for a buyer.

author: Jwillis
author_rank: Super Contributor
timestamp: May 20, 2023, 06:01:58 pm
content: Quote from: David Hess on May 20, 2023, 02:29:41 pmIs it AT&T blocking from the exchange or is it in the firmware? I unlocked and rooted my AT&T Kyocera for use on a Canadian exchange and haven't found any problems.

author: Siwastaja
author_rank: Super Contributor
timestamp: May 20, 2023, 06:14:45 pm
content: Quote from: David Hess on May 20, 2023, 02:29:41 pmI would say this is largely incorrect - I have never seen that on any cell I have tested or seen tested. Calendar fading increase from 80% to 100% has been in order of tens of %, not several times, on cells I tested, and I remember seeing a report on some Panasonic COTS cell in which calendar fading was actually stronger at 80% than 100%.Be careful with assumptions like this. The chemistry involved is pretty complex and full of manufacturer secret sauces. What seems to be generally true, though, is keeping below 65% brings significant improvements, as you mention.Cycling damage (specifically, caused by the charging process, not discharge) tends to be bad between 80-100%, but I would be careful not to oversimplify this, either, because current for example is a large contributor. I have seen significant lifetime improvements if you simply start tapering the current down already at 4.0V or so - i.e., earlier than CV phase.

author: AndyBeez
author_rank: Frequent Contributor
timestamp: May 20, 2023, 09:06:12 pm
content: Another significant factor in a LiPo's life is the operating and charging temperature. Hot batteries do not last. So that's no charging on a sunny window. However, from an engineering point of view, do mobile phone manufacturers NOT design effective BMS circuits? Surely, a battery charged to 100% can remain plugged into the wall for months with no impact on battery life? I note the current draw on the USB lead for a charged Sammy/Apple phone drops to a few milliamps, and stays that way. So called "battery savers" might need their own dodgy technology threadRelated to battery charging foo, the following JSON extract comes from theAnalyticsfile of a typical iPhone (iOS 16+). The significant entries arelast_value_MaximumFCCfor the factory full charged capacity,last_value_AppleRawMaxCapacityis the 'now' capacity, andlast_value_MinimumFCCis the 'dead at' capacity.last_value_MaximumCapacityPercentis the value displayed asBattery Health. Thelast_value_CycleCountis the number of times the battery has gone through a full charge cycle, not the number of times the battery has been connected to a charger. There are other metrics for age, temperature, voltage and amperage. So much metadata for a phone with just ONE battery!Code:{"deviceId": "f02bc3af5624dc9de922e4b53a45e1e664d5d199","message": {"Count": 3,"last_value_AlgoChemID": 5458,"last_value_AppleRawMaxCapacity": 1555,"last_value_AverageTemperature": 23,"last_value_BatteryHealthMetric": 345,"last_value_BatterySerialChanged": false,"last_value_ChemID": 5458,"last_value_ChemicalWeightedRa": 309,"last_value_CycleCount": 710,"last_value_CycleCountLastQmax": 1,"last_value_DailyMaxSoc": 72,"last_value_DailyMinSoc": 70,"last_value_Flags": 256,"last_value_FlashWriteCount": 1292,"last_value_GGUpdateStatus": null,"last_value_GasGaugeFirmwareVersion": 1553,"last_value_HighAvgCurrentLastRun": -930,"last_value_ITMiscStatus": 12588,"last_value_KioskModeHighSocDays": 0,"last_value_KioskModeHighSocSeconds": 0,"last_value_KioskModeLastHighSocHours": 0,"last_value_LastUPOTimestamp": 0.0,"last_value_LifetimeUPOCount": 0,"last_value_LowAvgCurrentLastRun": -103,"last_value_MaximumCapacityPercent": 84,"last_value_MaximumChargeCurrent": 2416,"last_value_MaximumDeltaVoltage": 50,"last_value_MaximumDischargeCurrent": -3681,"last_value_MaximumFCC": 1878,"last_value_MaximumOverChargedCapacity": 161,"last_value_MaximumOverDischargedCapacity": -78,"last_value_MaximumPackVoltage": 4352,"last_value_MaximumQmax": 1902,"last_value_MaximumRa0_8": 429,"last_value_MaximumRa8": 325,"last_value_MaximumTemperature": 501,"last_value_MinimumDeltaVoltage": 1,"last_value_MinimumFCC": 1493,"last_value_MinimumPackVoltage": 3024,"last_value_MinimumQmax": 1621,"last_value_MinimumRa0_8": 125,"last_value_MinimumRa8": 128,"last_value_MinimumTemperature": 67,"last_value_NCCMax": 0,"last_value_NCCMin": 0,"last_value_NominalChargeCapacity": 1559,"last_value_OriginalBattery": null,"last_value_QmaxCell0": 1666,"last_value_QmaxUpdFailCount": 3952,"last_value_QmaxUpdSuccessCount": 242,"last_value_RDISCnt": 154,"last_value_RSS": 302,"last_value_RaTable_1": 239,"last_value_RaTable_10": 310,"last_value_RaTable_11": 284,"last_value_RaTable_12": 336,"last_value_RaTable_13": 324,"last_value_RaTable_14": 368,"last_value_RaTable_15": 622,"last_value_RaTable_2": 287,"last_value_RaTable_3": 324,"last_value_RaTable_4": 348,"last_value_RaTable_5": 311,"last_value_RaTable_6": 295,"last_value_RaTable_7": 319,"last_value_RaTable_8": 320,"last_value_RaTable_9": 314,"last_value_ResetCnt": 0,"last_value_ResetDataComms": 0,"last_value_ResetDataFirmware": null,"last_value_ResetDataHardware": null,"last_value_ResetDataSoftware": null,"last_value_ResetDataWatchDog": null,"last_value_ServiceOption": 0,"last_value_TemperatureSamples": 322199,"last_value_TimeAbove95Perc": null,"last_value_TotalOperatingTime": 20137,"last_value_UpdateTime": 1683132412,"last_value_WeekMfd": 103,"last_value_WeightedRa": 309,"last_value_Wom_1": 47,"last_value_Wom_2": null,"last_value_batteryServiceFlags": 3,"last_value_calibrationFlags": null,"last_value_xFlags": 84},"name": "BatteryConfigValueHistogramFinal_V1","sampling": 100.0,"uuid": "ff35bd11-5bf0-4e73-a9be-e71b76b00d1e_A"}

author: Rick Law
author_rank: Super Contributor
timestamp: May 21, 2023, 03:29:07 am
content: Quote from: epigramx on May 20, 2023, 01:01:18 pmI hate to burst your bubbles. With the changing technologies, you will find disagreeing answers. The only way to tell for sure is if you get the info from the battery manufacturers. Absent that, one can only go with "typical" battery behavior which may apply to the battery in your phone -- or not.Take the skin of an airplane, every take off takes a little life away. Until metal fatigue gets to a point that the metal cracks and an 18 feet section of the airplane roof peel off and flew away mid-flight. Every charge-discharge cycle will age the battery a bit. A very very little bit but none the less a little degradation has occurred. Perhaps too small to be measurable, but hard to prove it couldn't/didn't happen. Heck, even if it is just sitting there doing nothing, some degradation is occurring.I understand that LiIon lost-of-capacity begins to be easily measurable 200 cycles in.(1) That was from > a decade ago when 18650s max out at 2000mAH. Much change occurred since so it may no longer apply.(2) I do know quality of manufacturing differs so one should refer to the info given by the manufacturer.(3) With this number being so old and manufacturer dependent, it may seem useless. It is useless as an exact number, but it does give you the magnitude you can expect -- low hundreds, not thousands barring very significant improvements.Typical for lithium recharge is the longer it stays in high voltage, the quicker it dies.(1) That said, your phone's charger may have the intelligence to turn off the charger for a fully charged battery. In this case, a plugged-in fully charged battery is not actually being charged so plugged-in or not is irrelevant when the battery is not under load (i.e. phone is off).(2) It is also typical that the fuller the battery is, the slower the uptake. That is, say if the battery is 1/2 full adding 10% more takes x second; however, when the same battery is 90% full, typically adding the last 10% will take a lot longer than x seconds. So, the last 10% from 90% to 100% is causing it to stay longer in high voltage than say from 80% to 90% -- so the fuller it goes, the more the degradation (per unit charged).(3) The faster you charge the battery (higher current charge) the higher the voltage it needs. So this may aid the degradation.Those are the "typical" rules I know. There may be other rules that I am too uninformed to know. Hopefully, other can add the "general rules to go by" and give you/us more "rule of thumb" to use. Do remember that "typical" is just that, typical. It probably applies to your battery, but it is also possible that it doesn't apply to your battery/charge because of their designs.

author: AndyBeez
author_rank: Frequent Contributor
timestamp: May 21, 2023, 10:14:57 am
content: For long term storage and shipping, batteries should be maintained at 50% capacity and kept between 15 to 25C - that's one rule of thumb.I should add in the case of iPhone batteries, an observation is that battery capacity (or Health) is not strictly related to the number of cycles. It follows that charge cycles reduce capacity, but temperature seems to play an important role in the reduction of capacity too. Hence, batteries with a higher average temperature and fewer charge cycle counts can, be as degraded or worse than batteries with lower average temperatures and higher charge cycle counts. Go figure?From my JSON posted above there are some otherweightingsthat are obviously taken into consideration when working out the rate of capacity decline. So what is best for a battery is as much art as science.FYI the iPhone analytics file can be viewed in the raw by temporarily enabling the share analytics (with Apple) option.Settings > Privacy & Security > Analytics & Improvements > Share iPhone Analytics = ONAs this is anaggregated daily fileyou need to wait for midnight, after which, a new file is created.To view use :Settings > Privacy & Security > Analytics & Improvements > Analytics Data > VIEWYou'll be looking for a file namedAnalytics-{TIMESTAMP}.ps.ca.syncedOnce you have share-airdropped the file off of the phone and into your IDE/JSON viewer, set the share iPhone analytics option back to OFF.btw There is also an iPhone app calledCoconutwhich displays the battery status in a nice UI screen.https://www.coconut-flavour.com/coconutbattery/++ EDIT - I spotted a video on YouTube of a guy replacing an iPhone battery; he splits the LiPo cell pack from the BMS board and then spot welds a new cell pack to the existing BMS. Do not do this at home. The flash memory onboard the BMS is expecting the chemistry of the old cell and not the new one. Expect a major malfunction.

author: beanflying
author_rank: Super Contributor
timestamp: May 21, 2023, 11:51:41 am
content: Just about to replace my Battery in my S7 (first time and the new one is on the bench) I maybe needed to do this last year sometime but I have been comfortably getting an entire days use (lowish level) still so I didn't worry about it to much. I got is early in the life cycle so it is now circa 6 years old and has gone on charge overnight everyday to full then used and repeated so about 2000 cycles I guess.As a long term user and storer of LiPo's for R/C use for way longer than that then this is where you want to keep them well off full as they spend way more time not being used than in actual use. This is where 4.2V/cell storage is a killer and puffer of cells. This is NOTHING like phone usage and this and similar use cases including occasional use tablets and laptops are best left below full.For your phone and as an Aussie there is plenty of warmer to high temps in that but don't leave it on charge and full for extended periods and stress less batteries are cheap if needed.

author: radiolistener
author_rank: Super Contributor
timestamp: May 21, 2023, 11:58:37 am
content: if you want to extend battery life, you're needs to extract it from the phone and keep unconnected.

author: Rick Law
author_rank: Super Contributor
timestamp: May 23, 2023, 12:49:37 am
content: Quote from: radiolistener on May 21, 2023, 11:58:37 amBut they are getting so hard to open these days...With the earlier Asus (Zenfone 2), opening it to connect/disconnect/replace a battery is easy. With these glass phones, opening it appears to be for the devoted instead of casual users such as myself.

author: beanflying
author_rank: Super Contributor
timestamp: May 23, 2023, 12:59:10 am
content: Go back far enough and phones had several batteries to get through a long day at higher useMy first Motorola Bag phone got used with a pair of 12V AGM's as it ran a higher power mode, its successor flip phone had a slim and fat battery option.Just looked up a video on getting into my S7 that bit looks ok at least getting it back to 'waterproof' (IP68 original) might be another matter

author: MathWizard
author_rank: Super Contributor
timestamp: May 24, 2023, 01:33:58 am
content: I have a rechargeable PS4 controller that I hardly ever use. It has a LiPo battery, IDK if I should charge it some, once and a while. Same with my new graphing calculator, so far I've not used it much, I bet it has a LiPo battery too. I can keep them cool tho, in a box on the floor.