Charging your phone battery overnight is bad (according to Linus Tech Tips) - Page 1
Forum section: electronics / general

author: Halcyon
author_rank: Unknown
timestamp: May 11, 2018, 07:50:20 am
content: I smell bullshit. Maybe those who know more might be able to comment?

author: Miyuki
author_rank: Frequent Contributor
timestamp: May 11, 2018, 08:10:36 am
content: From battery chemistry point of view he say truth on most phones battery is in reality overcharged to get better usage time at cost of very low cycle life and fast degradation

author: Halcyon
author_rank: Unknown
timestamp: May 11, 2018, 08:21:39 am
content: I only have anecdotal evidence to the contrary, but ever since I owned a mobile phone with a Lithium-based battery (I think it was the Nokia 5110), I've charged it, every night, by plugging it in when I go to sleep and I've never had a battery fail me in the first few years. Actually, I don't recall *ever* needing to buy a replacement battery for a phone and I generally use my phones every day for 3-4 years before replacement.Some of the earliest Nokia batteries from over 10 years ago still manage to hold a charge for several hours.I am careful not to charge Lithium batteries in hot environments or exposed to sunlight where they can warm up significantly, but even with Samsung's "Adaptive Fast Charge" (based on Qualcomm's Quick Charge technology) the battery/phone does not heat significantly, even after a prolonged charge.

author: Miyuki
author_rank: Frequent Contributor
timestamp: May 11, 2018, 08:53:09 am
content: He is talking about this phenomenabut this is for full discharge, if you discharge to 50% it will double the cycle count and if you don't use phone much during day a discharge to like 75-80% you will get thousands of cycles anyway

author: Halcyon
author_rank: Unknown
timestamp: May 11, 2018, 09:04:21 am
content: Sure. Lithium batteries don't like being "deep" cycled. Shorter, more frequent chargers are better and this all comes down to usage patterns. However to say not to leave them plugged in overnight is misleading. There are enough click bait articles out there which basically say the same thing (and even make insane claims like you'll "overcharge the battery" by doing so).I don't like Linus, he irritates me, but a lot of his content is quite good. However I think this time he dropped the ball a little. The average consumer is going to gloss over graphs, charge/discharge curves etc... and just remember that charging overnight = bad = danger.You would think by now major phone/tablet/laptop manufacturers would have worked out how to best charge a battery?

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: May 11, 2018, 10:51:39 am
content: Mooooo....My phone is 5 years old and the battery is still doing well. If it's at home, it's connected to the charger. If it's in the car, it's connected to the charger. Get a cheap USB voltage/current tester and watch the current draw. When fully charged, the current drops to zero.This used to be a problem with rechargeable NiCd batteries for my underwater video equipment. You had to let the battery drain fully before recharging.

author: tszaboo
author_rank: Super Contributor
timestamp: May 11, 2018, 11:00:03 am
content: Proper phones will be smart enough not to ruin your battery. Proper phones also have replaceable battery. Also this "you can charge it twice as many if you only use 50% of the battery" is true. But did you notice, that all you do is charge it more often? If we ignore microcycling, it doesnt really matter how you use your phone, just dont let the phone die with 0% battery left. And if you are really concerned about his, buy a charger which switches off when the charging current is below some limit.

author: hans
author_rank: Super Contributor
timestamp: May 11, 2018, 11:24:00 am
content: I wouldn't stop charging to save the battery, but rather to save my house. Although it's rare, it can happen that a lithium cell was damaged with a deep discharge (for example), and then when left charging unattended could catch fire. I wouldn't want to be sleeping next to such an event..I see some people taking out their laptop battery if they use it on the charger. This way they say their battery is still good after 4 years of 'use' (or rather: avoiding use).Either their argument is that their laptop has a shitty power circuit where the consumed current of the device passesthroughthe battery (i.e. it being charged and discharged at the same time - not sure how they think that should work since currents sum up..). Or they don't prefer to have the battery sit being trickle charged to near 100% in a hot enclosure (makes more sense - although my laptop doesn't start a charging cycle if it's >95%).I personally don't care much, the battery is in there for convenience of use, and I'm pretty certain that after 4 years of usage I will upgrade my devices anyway.I think you would need to go pretty far extremes to kill lithium batteries this way. They may age, but not necessarily damage. Deep discharging is really bad though, and I've seen batteries degrade with massive steps the few times I accidentally done it on my old phone.

author: Brumby
author_rank: Unknown
timestamp: May 11, 2018, 12:36:41 pm
content: I've always followed the same regime for quite a few years now ....When the battery gets down to somewhere in the 40% - 50% mark, the phone goes on charge overnight. I never replaced a handset within 2 years and I have never had a battery fail to last for at least 2 days between charges - and that is with a modicum of use.My previous handset was a Galaxy S4 which has been assigned a new role. While that role is not particularly demanding, it still lasts more than 3 days on a charge ... and it has been in use for more than 4 years.Mind you, I use these things mainly as a phone, sometimes as a camera and occasionally to browse the internet. I don't live on 24x7 music, videos or gaming - so that's going to help.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: May 11, 2018, 12:56:00 pm
content: But.... This is why any modern phone has battery management systems.Arrgghh this is why I don't like a lot of tech-youtubers. Making this kind of wrong claims and people listen to them, over a bunch of engineers and researchers who spend parts of their life working on this.

author: Peabody
author_rank: Super Contributor
timestamp: May 11, 2018, 01:07:32 pm
content: Quote from: hans on May 11, 2018, 11:24:00 amWhat we call the charger is really just an external power supply. The circuit that does the controlled constant current, then constant voltage, battery charge is in the phone. That circuit provides the power supply current directly to the phone if it's being used while plugged in, and at the same time independently provides charging power to the battery. So the battery will never be both charging and providing current to run the phone at the same time. When the battery is fully charged, the charging process will shut down completely, and the phone will continue to operate off the power supply if it's plugged in.And lithium charge circuits do not trickle charge. When the battery is fully charged, the charging shuts down. If the battery self-discharges enough (your 95%), the charging process will resume, but then shut down again when fully charged. So it cycles, but doesn't trickle.I believe this has all been worked out, and as far as I can tell, if it's convenient to have it plugged in, it should be plugged in. If it needs charging, it will charge, and if it doesn't, it won't.There is a setting on my computer that only charges the battery to 80%, on the theory that the battery will last longer. I don't know about that, but I don't think it's something you see on phones.

author: apis
author_rank: Super Contributor
timestamp: May 11, 2018, 01:36:35 pm
content: Quote from: Peabody on May 11, 2018, 01:07:32 pmYes, you are pretty much stuck with whatever charging algoritm the device is supplied with. Trying to only charge your phone to 80-90% is hopeless unless you are willing to spend your time checking the phone charge constantly. It's nice that some computer manufacturers have begun giving you the option, but you are also more likely to have your laptop plugged in for prolonged periods of time.

author: rrinker
author_rank: Super Contributor
timestamp: May 11, 2018, 01:43:51 pm
content: Anecdotal evidence here, but my current phone is an iPhone 5s. I got it a few months after they came out, so you can figure the age. I have ALWAYS plugged it in overnight - to an iPad charge to boot. During the day when I am not home, I plug in my iPad. The iPhone still has no problems lasting all day on a charge. I don't have battery anxiety. There are times when it's been off the charger for more than 12 hours - 8am to 10pm, and then my best friend calls and we have a 4 hour conversation. That usually gets the battery down there - 25-30% left. Same with the iPad - sometimes I go days before putting it back on the charger, but I don't use it that heavily, usually just reading. Until I dropped it and destroyed the glass, I was actually using a rather old iPad as well - the first one with a Lightning connector. Would go all weekend if I was mostly reading, despite its age. Normally it gets charged every day - after being used (and mostly sitting there) overnight, it only tends to drop to 89%.I'm sure this somewhat depends on the design of the device, and the quality of the charge control circuit.

author: apis
author_rank: Super Contributor
timestamp: May 11, 2018, 02:00:08 pm
content: I do the same with my phone and never had any problems.The percentage might be misleading though, since it is the voltage that matters and there's no way to see how they calculate the percentage from the voltage. It might never actually charge the batteries to 4.2V after all.

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 11, 2018, 02:03:57 pm
content: Quote from: apis on May 11, 2018, 01:36:35 pmYou can use an app like Llama to beep when it reaches the charge level you desire, or a "close enough" solution is one of those timers that switches on for a predetermined time by pressing a button.

author: apis
author_rank: Super Contributor
timestamp: May 11, 2018, 02:12:19 pm
content: Quote from: NiHaoMike on May 11, 2018, 02:03:57 pmYes, that could work for a phone. Not for the laptop though, since I want to keep it mains powered even after the battery is fully charged. And cycling the battery got to be worse than just leaving it on 100%.

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 11, 2018, 02:37:33 pm
content: Quote from: apis on May 11, 2018, 02:12:19 pmIf it's a Lenovo, there's a script for that.https://github.com/teleshoes/tpacpi-bat

author: RobertPS
author_rank: Contributor
timestamp: May 11, 2018, 02:43:17 pm
content: Quote from: hans on May 11, 2018, 11:24:00 amIn the past some (most?) laptops needed the battery to be present for maximal performance. The power supply on it's own couldn't deliver enough power. I don't know if this is still the case.

author: apis
author_rank: Super Contributor
timestamp: May 11, 2018, 02:54:24 pm
content: Quote from: NiHaoMike on May 11, 2018, 02:37:33 pmNice! but unfortunately mine is not a Lenovo. I don't know if something like that would be possible with my model, it would require those functions are supported by the hardware.

author: hans
author_rank: Super Contributor
timestamp: May 11, 2018, 03:13:33 pm
content: Quote from: RobertPS on May 11, 2018, 02:43:17 pmSometimes. The same friend has a HP notebook with a 45W charger. I bet if you connect a 2.5" external HDD, turn BL on 100%, put full load on internal SSD, CPU and GPU, that you'll either use the internal battery or see throttling CPU/GPUs.He also says that if he is charging the battery and putting a heavy load on the system, he can see the charging time go up.In contrast my Lenovo P50 has 130W brick. My dock has a 230W brick. Aside from the hypothesis that you could probably draw 230W if you put all peripherals to use (including charging 6 tablets from USB?), it's also nice that I never have to worry about power limits.Quote from: Peabody on May 11, 2018, 01:07:32 pmThanks for the correction, I shouldn't have used the word "trickle" charging, as we're not using NiMH's anymore :-) Anyway, apparently some implementations did keep charging the last few % everytime, which is kinda pointless. But I've never seen it on my devices..I think those incidents with Lithium batteries catching fire or exploding is quite rare. I believe Lithium batteries are some of the safest batteries when the protection circuitry is included.

author: rdl
author_rank: Super Contributor
timestamp: May 11, 2018, 08:13:03 pm
content: I use my phone until the charge drops to 75 or 50%, then charge it overnight. Occasionally, if I forget or don't use it for a while, it has dropped to almost zero or even shut off, but I don't worry about it too much. It's a $15 phone and probably wouldn't be worth it to replace just the battery.

author: G7PSK
author_rank: Super Contributor
timestamp: May 11, 2018, 08:52:12 pm
content: I set my phone to switch off at 20% of charge, I charge it once a week and when I do it's over night. The cell protection and charging circuit should look after the battery if it dose not you have the wrong phone. So far I have had no trouble with batteries and over the last 15 years had two phones and never had to replace the battery The phone I have at present is three years old, I only got it as I decided I wanted a better camera in the phone than the old one which I still have as a reserve with the original battery in it.

author: IanB
author_rank: Super Contributor
timestamp: May 11, 2018, 09:04:19 pm
content: I know that charging stops on my iPhone when it reaches 100%, so it makes no difference whether I leave it charging overnight or whether I charge it to 100% during the day and then unplug it.It is true that if I charged my phone to 80% before unplugging it and recharged it as soon as it got down to 30% I might get a slightly longer lifetime out of the battery. However, life is too short to worry about such things. The incremental gain would not be worth the effort.

author: maukka
author_rank: Unknown
timestamp: May 12, 2018, 07:54:05 am
content: Quote from: apis on May 11, 2018, 02:54:24 pmAlso possible with a Dell. Mine is an XPS 15 (9560)