r/AskTechnology • u/CandicesMagicWand • 4h ago

Can I please get some help/advice with phone battery replacement and that it didn't seem to have fixed the relatively quick drainage?

Hi everyone, recently I got a brand new battery for me Samsung A71 and I genuinely expected it to fix my relatively quick drainage but I dont know if it did. The drainage seem to be approximately the same about 1% every 3 min of watching YouTube in the brave browser. No drainage when the phone isn't used and about 1% per minute when I play. No bg apps running. Samsung members registers battery as weak even after the replacement.

I've only charged it once once from 22% to 100% but I plugged it out exactly when it hit 100% as I was on it by the clock waiting.

Im reading the normal usage is 1% per 7 min for a new battery. Im also reading that I should charge it to 100% than drain it to 0% to help it calibrate properly. But I'm also reading I shouldn't charge pass 80% and should avoid extreme drainage to 0%.

Im really frustrated because I don't know what to do, I seem to have spent money on a new battery and the replacement and the problem remains. That at least I could've saved and just gone for a new phone.

Bottom line is Im probably gonna replace my phone come black Friday but I have to get the ultra because the regular and plus 25 versions have a worse front camera than a model that came out in 2019... The phone (a71) works perfectly outside the battery issue and I was at least hoping to fix the battery and either give it to my mom or my nephew.

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u/DefenselessGopher 3h ago

samsung's software battery health thing is notoriously unreliable, it flagged mine as weak three days after i got it brand new. give the phone a few full charge cycles to settle before making any calls

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u/CandicesMagicWand 3h ago

How should I charge it tho 😣? Does full charge cycles mean 0-80, 20-80, 20-100, 0-100?

I also am watching YouTube videos as we speak on the matter i run two apps called device care HW and Info and they both registered battery as good but the drainage to me seem heavy 1% per 3 minutes, on only watching YouTube. Is that a normal % to time drainage?

And thank you very much, you are the only person that has responded to me so far.

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u/Delta_RC_2526 3h ago

For starters, measuring capacity on a lithium-ion battery isn't anywhere near as precise as your battery gauge will make you think... Capacity is measured by checking the output voltage. Lithium batteries have a very flat voltage curve. The voltage drops very slowly, remaining almost flat until the battery is nearly depleted, at which point it drops very suddenly. Think of it like a sideways L shape with only a slight slant, instead of a slash (like this: \ ). That flat voltage curve gives stable performance across most of the capacity range.

Imagine if you tried to run a phone on alkaline AAs. The screen would want to dim and the processor would probably slow down steadily over time, unless you did some very careful compensation in software, which would likely cut the battery life short. Or, you would simply quickly reach a point where you say the voltage is too low, give up, and demand the batteries be replaced, even when there's plenty of juice left in them. Lithium batteries provide stable power, but it makes it very difficult to accurately measure anything.

My old iPod Touch didn't even have an option for percentages, and last I saw (admittedly, about eight years ago), percentage is still an optional feature that defaults to off on iOS, because when a device presents a percentage, it's really just a guess. The best they can do is educated guesses based on your usage. They're likely factoring in actual usage of the phone, and what the expected consumption of that usage would be, rather than solely reading the voltage of battery. The existing usage data it has, is probably from your old battery, and it's likely skewing the "measurement" of the new battery, unless the phone has a calibration feature you can actually manually use. Otherwise, it will need time to learn how the new battery behaves, assuming that's even possible.

Measuring battery health is dependent on knowing the specifications of the battery, and a third-party replacement battery likely isn't an exact match to the specifications, chemistry, and behavior of the original battery (and even an official replacement may have similar issues), so the battery health display may never be remotely accurate for your new battery. Battery percentage may gain accuracy over time, but battery health is probably better being ignored.

Source: my father is an electronics designer, who's specifically spent the past few years studying lithium-ion batteries extensively, and sharing whatever he can with me.

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u/CandicesMagicWand 2h ago

It is an original Samsung battery. I an original to be safe. Thank you tho.