Phone charging seems strange

[JonathanM]

I've recently bought a new smartphone, with a standard lithium battery.

Every other lithium battery device I have had charges in stages. They go quite quickly up to 80%, and then really slowly for the last 20%. This new one, however, charges in a completely linear fashion. Every 1% of charge takes about 1 min 30 seconds, all the way from low charge to 100%. Is this normal these days?

 

[Pat ex]

It's been nearly 2hrs now & I'm utterly & absolutely GOBSMACKED that DiyNot (General Discussion Div') hasn't yet provided an expert answer to this genuine query.

It's not in the appropriate DIY section.
I've asked for it to be moved.

Don't mention it to Mottie, he thinks all forums are only for DIYers.

 

[Justin Passing]

Pity Dork didn't answer.
My Samsungs charge at a more or less even rate, but you can invoke an 85% max, for battery life.
Weedy wireless chargers tend to slowdown as the voltage rises, which is fine.

Fast chargers work from a higher voltage, so they aren't as sensitive to battery voltage.

Heat kills phone batteries, as do chargers which can't measure charge state (few of those left). Check if the thing goes cold eventually - it should.

 

[Ihavenojob]

Most rechargeable items take a while to bed in.

 

[IT Minion]

You could be charger limited.

If your phone can accept a high current to start with, then a slow current at the end, but your charger can only deliver a tiny current at any time then you'd get a flat charging rate.

Charging a phone in 150 minutes, or 2 hours 30, is really slow by modern standards. 50% in 30 mins is more the standard.

 

[JonathanM]

You could be charger limited.

If your phone can accept a high current to start with, then a slow current at the end, but your charger can only deliver a tiny current at any time then you'd get a flat charging rate.

Charging a phone in 150 minutes, or 2 hours 30, is really slow by modern standards. 50% in 30 mins is more the standard.

It only accepts 10W max. I'm a very light user, so I bought a very cheap phone!

EDIT: I've tried it with a 15W charger but it's exactly the same.

I'm thinking they may have deliberately skewed the state of charge figure, to make it linear, so that it easy for people to understand, and that it bears no relation to the actual SoC.

 

[IT Minion]

It only accepts 10W max. I'm a very light user, so I bought a very cheap phone!

EDIT: I've tried it with a 15W charger but it's exactly the same.

I'm thinking they may have deliberately skewed the state of charge figure, to make it linear, so that it easy for people to understand, and that it bears no relation to the actual SoC.

You may have checked but sometimes cables are the limiting factor, especially now with USB C.

Or the charging port is limiting things rather than the battery behind it.

 

[JonathanM]

You may have checked but sometimes cables are the limiting factor, especially now with USB C.

Or the charging port is limiting things rather than the battery behind it.

So far, I've tried the supplied 2A charger, and my Chromebook charger which can supply 3A at 5V, each with their own cable.

I don't have any more cables to try!

EDIT: It's a 4000mAh battery. So that's the same as 4Ah. So, at 2A (the max it can handle I think) will it take a minimum of two hours to charge it fully? It's the linearity that's puzzling me, not the overall time.

It is USB-C

 

[Mottie]

I've recently bought a new smartphone, with a standard lithium battery.

Every other lithium battery device I have had charges in stages. They go quite quickly up to 80%, and then really slowly for the last 20%. This new one, however, charges in a completely linear fashion. Every 1% of charge takes about 1 min 30 seconds, all the way from low charge to 100%. Is this normal these days?

How recent? With iPhones, it get to take some time before recognising your regular use pattern. Say you put it on charge at 11pm and take it off charge at 7am every day, it will eventually recognise that and finish charging at 7.00. I think it fast charges to 80% and then trickles to 100% by 7.00 am. Well, that’s what our iPhones do.

 

[JonathanM]

How recent? With iPhones, it get to take some time before recognising your regular use pattern. Say you put it on charge at 11pm and take it off charge at 7am every day, it will eventually recognise that and finish charging at 7.00. I think it fast charges to 80% and then trickles to 100% by 7.00 am. Well, that’s what our iPhones do.

Just over two months ago now.

My phone isn't that smart!

 

[Justin Passing]

What phone is it? There may be info online about it.

If you've ever taken a phone battery apart you see a circuit board with one or two chips on it plus passive components.
They're often multi function things which, if you look at the data sheet, you'll see can control and use a range of parameters. Such as temperature , voltage, max charge and discharge rates, shoulder voltages, discharge minimum voltage, and stuff to do with detecting the charge state of the battery.
Some at least do the last by turning off the charging, applying a load to the battery and seeing how far the voltage drops. That has times and voltages which (I guess) can also be varied . (Checked the data sheets for some of the chips.)
I don't pretend to know what's being used now but it has clearly changed, because over the years they've changed the one to two chips they use. Maybe one controls one thing, another another, etc. The last battery I went in had two chips which were capable of doing much the same, so - pass.
If your phone (battery) has a chip which slows charging at some percentage, which would likely depend on the temperature of the battery, that would be a good thing for total battery life.
If you look into battery construction, which is also changing all the time, there's a lot of ion diffusion going on. If you try to do it fast and hot, it gets hotter, gases form etc. They used to catch fire in aeroplanes... Best to control things.
Using my phone as a dash GPS in car in the very hot weather, the battery got hot - something like 60°, (I have an app to measure the battery temp) and it stopped charging. I was on the M1 so turned it off an put it by the aircon. I was concerned that I'd cooked it but it's ok now.

4Ah should give you a darned good usage duration, so don't worry about it.
There will probably be a low power mode on the phone. If not, turn things off when you aren't using them, like off bluetooth, wifi (eg if you're in a car), GPS if you're at home, etc. My Lock screen with a fairly bright calendar on it uses a few % per day.

 

[Neil a]

did u buy proper leads and charger (if u didn’t get with the phone) which you don’t now ? Pound shop leads and chargers do this it takes three days if ur lucky to charge..

 

[JonathanM]

4Ah should give you a darned good usage duration, so don't worry about it.
There will probably be a low power mode on the phone. If not, turn things off when you aren't using them, like off bluetooth, wifi (eg if you're in a car), GPS if you're at home, etc. My Lock screen with a fairly bright calendar on it uses a few % per day.

Thank you, again, for the great info.

The usage duration is actually really good. I suppose my worry is really about safety. I've read many times, over the years, that the reason for the stepped charging, where the last 20% is a lot slower (several times slower), is to stop damage to the battery. And when I noticed mine was doing something different to other devices, it may me wonder if there was a problem.