Fast-charging vs. normal speed charging that takes too long

[jdocdp]

Hi everyone,

I've read that one should avoid fast-charging mode (when it's not needed) for the sake of the battery's longevity.

However, when I disable it and plug to charge my phone normal speed, it actually charges reaaally slow. Probably takes me 4-5 hours to charge from 20 to 100% (while using the phone), which is ridiculous, and yes I've tried several sockets in my house.

Anyway, in general terms, as far as the battery is concerned (or even the phone itself), which is less damaging?

→ a. Fast-charging mode
→ b. Normal-speed mode that takes too long (as described above)

Thank you.

 

[B. Diddy]

Which phone do you have? Going from 20 to 100% over 4-5 hours while actively using the phone actually doesn't sound too unusual to me. Remember also that the charging curve isn't linear -- it's a steeper curve from 20 to around 80-90%, but then flattens out as you approach 100%.

Theoretically, fast-charging will generally put more stress on the battery, and therefore might decrease its overall lifespan. Normal or slow charging is therefore better for longevity, but it's hard to say how much better. If you use a device for only about 2 years before upgrading, then it probably doesn't matter that much.

 

[jdocdp]

I see. Thank you for your response.

Well, I mean, in standard charging mode, it literally looks like I have it plugged just so that it doesn't drain battery and not that it really charges. Even when I don't use it, it'll take probably 3 hours to charge 20-100%. And yes I have noticed that from about 85 to 100% it charges slower.

Reason why I asked is that even though fast charging raises the temperature, it takes 30-40 mins for an adequate charge. I can go without my phone for 30-40 mins.

But with standard mode it takes hours, so I end up using it while charging, and the result is a raised phone's temperature anyway. So I wonder, is it really that fast charging is worse for the battery (than standard charging) given the circumstances? Raised temperature ends up being inevitable. :/

I've an S6 Edge by the way.

 

[B. Diddy]

When it's plugged in for standard charging, are you using a wall outlet or USB port? Have you tried a different standard charging plug? When it's standard charging, go to the Settings>Battery​ menu -- does it say it's Charging AC or Charging USB?

 

[jdocdp]

It's the exact same wall socket whether I charge standard or fast. I use the factory charger that my phone came with (the one with the microUSB to USB cable which connects to the plug that goes in the wall socket).

 

[B. Diddy]

Ok, but does the phone say it's Charging AC or Charging USB when plugged in? If it says USB, that means the phone isn't recognizing the charging source correctly, which is probably due to a problem with the charging plug -- that's why I suggested trying a different charging plug.

 

[jdocdp]

Hmm, it doesn't clarify whether it's USB or AC, actually.

It just says "charger connected", "cable charging", "estimated time remaining...", you know stuff, like that.

I went to Settings > Device maintenance > Battery and I also checked on my notifications. No mention of USB or AC in either one. :/

Anywhere else I could probably check?

 

[B. Diddy]

I've seen it on the lockscreen as well, but that probably depends on the phone.

 

[droidgr]

Don't expect to charge your phone fast while using it, most manufacturers apply limitations if you use the phone and charge simultaneously.
For example on LG phones they force a 200ma limit when the screen is on, so even without you touching the phone if the screen is on, the charge drops from 2000ma to 200ma.
Manufacturers apply this limitation to keep the phone from over heating and degrading the battery and electronic components.

 

[jdocdp]

Yeah I guess that might be the case.

So if I have to choose between:
a. 4-5 hours of standard charging and use at the same time,
or
b. 35-45 mins of fast charging without simultaneous use,

which one would be less damaging for the battery and/or phone?

 

[B. Diddy]

I'd say that standard slower charging will always be slightly better for the battery than fast-charging (regardless of simultaneous use) -- but again, in the context of how long an average user holds onto a phone before upgrading, the difference will probably be minor.

 

[jdocdp]

Is that right? Wow, I'd expect the opposite to be honest.

I dunno, I don't have high demands from a phone in general, so even though it's a 2015 model (purchased in late 2016), it's safe to say I'm planning to keep it for another couple of years.

 

[B. Diddy]

Battery University is where I get a lot of information -- check out these sections:

How to Prolong Lithium-based Batteries - Battery University
Fast and Ultra-fast Chargers - Battery University

 

[Uranium-235]

I charge my battery with an old Samsung flipphone charger (have an s8+). The charger is 5v 1a. It does seem to charge fairly fast (though never says fast charging), but I use the 20/80 rule. I have never dipped below ~30% most days but my usage mostdays is limited

Of course, the charger gets pretty hot