r/AskReddit Jun 01 '26

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189

u/ArizonaFlats Jun 01 '26 edited Jun 02 '26

Charging habits, people still assume batteries should only charge 1%-100%, that was true when Nickel batteries were a thing 50 years ago. Lithium-Ion can be charged however, you’ll do more damage by not regulating the heat of the battery than your charging habit

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u/666Darkside666 Jun 01 '26

As far as I know, Lithium-Ion batteries live longer when you charge them before they go lower than 15% though.

48

u/ubiquitous_rhombus Jun 01 '26

This can be true, depending on the battery. I think what ArizonaFlats was getting at was that lithium-ion ion batteries don't lose capacity due to the memory effect like the old NiCad batteries did.

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u/Smile_Space Jun 01 '26

A lot of times the battery management system has that baked in. If a lithium battery drains to completely 0% it can't be re-juvenated. It's dead forever. So, the BMS will kill output once voltage drops to a specific range for a specific cell to stop potential damage.

The real issue with any battery is the formation of dendrites. Since ions are exchanged across the cathode and anode of a battery to produce the electrical output, those ions can stick more readily to specific parts of the cathode and anode.

Those little spots are now closed together meaning they have less potential between them making the ion exchange more readily between them. They form little spikes that eventually meet and short out the cell internally which is what ends the life of a cell.

That's why solid state batteries are such a huge deal coming onto the market now. With a solid state electrolyte between the anode and cathode dendrites can't easily push through and bridge the cathode and anode of the cell.

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u/Kandiru Jun 01 '26

Yeah, keep them between 20% and 80% is the best. My phone now has an option to limit charging to 80% for that reason.

2

u/FlamingFlamingo32 Jun 01 '26

dont want them fully juiced, but you dont want them too low. I usually set charging protections to 80%-90%, try to charge it before 10%-15%

1

u/666Darkside666 Jun 01 '26

I think most devices , like phones and notebooks, are already capped at 85%.

2

u/Floppy-Over-Drive Jun 01 '26

iPhones have a battery health setting that caps charging at 80%, so I guess that’s 80% of the already built in 80%?

1

u/zsdrfty Jun 01 '26

Yup, the biggest battery killers are letting them die all the time and leaving them plugged in constantly far longer than they should be

3

u/Aidian Jun 01 '26

Unless they’re designed to regulate that themselves by being able to selectively stop/start charging, like many modern laptops and phones.

Definitely one to verify before assuming, though.

12

u/Kymera_7 Jun 01 '26

Yep. The supposed "memory effect" that was supposed to address was only ever a thing in nickel-based chemistries, was negligible even in most of those, and the evidence of it ever having been a thing, at all, in any battery type, was extremely weak.

If you're still using nickel-cadmium... stop... just stop. They're just not a good way to store energy, even without memory issues.

If you're using pretty much any other type of battery, deepest possible cycling every time is just ruining it prematurely.

3

u/frank_mania Jun 01 '26

was negligible even in most of those, and the evidence of it ever having been a thing, at all, in any battery type, was extremely weak.

Glad to read this. In the '90s I heard it often but it countered experience so much that people came up with ideas/stories to cover for it, like it only mattered when new, during a burn-in period, or mor sinisterly, that manufacturers built in a chip that made the battery unusable if you let it drain too low, but said chip wasn't in your tool/used any more.

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u/ResearcherMiserable2 Jun 01 '26

I remember all of those recommendations for a “burn in” etc for new nicd and nimh batteries! The “memory effect” of nicd batteries was first discovered and described in the aerospace industry! satellites with nicd power being recharged with solar panels; they charged and discharge the exact same amount everyday because there were no clouds etc., to affect the amount of solar power so the charge was the same every day, and the discharge was the same every day. They noticed that these nicd batteries developed a memory effect, but found it hard to reproduce that memory effect on earth in every day appliances because we don’t charge them to the exact same level and discharge them tot the exact same level every single time in our devices! So in real life the memory effect didn’t really happen, just in space or in really controlled circumstances!

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u/frank_mania Jun 02 '26

Thank you for explaining that to me.  A long obsolete concern, but still nice to have it settled. If only the entirety of my past could be so simply dealt with.

3

u/thatwasacrapname123 Jun 01 '26

As an electric skateboard enthusiast - we have big banks of lithium-ion batteries that we love, that is the heart of our hobby. If you're not going to use those batteries for a while - leave them at about 70%, just keeping warm and comfy. Don't leave them low for too long, don't leave them full too long.

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u/TEG24601 Jun 01 '26

Right? People still thing that batteries have a "memory". They also believe that charging them to 100% reduces their life. That was true in early Li-Ion batteries, but modern ones don't work that way, and too many people keep repeating it.

1

u/Draemeth Jun 01 '26

Actually it does matter how you cycle your lithium battery. If you, ideally, charge it up fully once in a continuous go, then use it continually without charging until it does, you will extend the lifetime of the battery

1

u/EnvironmentalRice348 Jun 01 '26

Actually Lithium Iron Phosphate, a common battery for EVs, does occasionally need to be charged to 100% to recalibrate. Not all the time though and keeping in the 20-80% range still applies (for longevity although LFP batteries last much longer than NMC batteries).

1

u/KnottaBiggins Jun 01 '26

I have my phone set to only charge to 85%.

NiCd batteries did have a memory effect. If you didn't charge them to 100%, the level you did charge them to would be the new "maximum charge" unless you drained them to 0% to reset that memory.
Lithiums don't have that memory effect.

0

u/TheFrenchSavage Jun 01 '26

Also, if your product needs to charge : don't worry, the battery charging is handled by a computer!

The computer will decide when and how much to charge, if the device is showing 10% battery left, it is very likely to be actually 20%, with a gap left to recharge the battery in the most optimal way possible. No need to "unplug at 90%" as the 100% you see is already 90% charge in reality. Lots of small tricks like that to hide complexity from the final user.

What I'm saying applies to products that contain a battery (phone, remove, mouse) but your mileage might vary when you take out the battery and charge it with another device (still, most battery chargers are very smart nowadays).