pro1x Unexpected charging behaviour, with the current dropping the more the closer we come to fully charged?

[Rob. S. 1,616]

It's nearing three months that I'm using the Pro1X as my daily driver, and I'm still (mostly) happy with it! Now I wanted to have a look at what AccuBattery says about battery health. It says 92% capacity, 3,031 of 3,300 mAh (sounds less than optimal but then again my second-hand Pro1 has kept its capacity around 2,950 mAh for the whole 1.5 years I've been using it) it also says "we have no full charges detected yet". 

Right, I do mostly use the Chargie device which stops charging at 80%, still I know I've fully charged it more than once. But to make sure, I did let it go below 15% (as AccuBattery suggests) and let it fully charge over night.

Still "no full charges detected". Huh?

Looking at the "history" view in AccuBattery, two charging periods were recorded. One from 11% to 97% (3h 20m) and another one from 97% to 100% (9m).

Strange. Tried again the following night. Very similar result, two charging periods, 14% to 95% (3h 20m) and 96% to 100% (9m).

Then I tried again by day, with a different charger. 

Again two charging periods, 13% to 98% (2h 13m) and 98% to 100% (2m).  

But I've also noticed that at some point the charging current slowly begins to drop—until it's somewhere between 100 and 200 mA just before full charge is reached, if I remember correctly. Looks like it could be some built-in battery preservation scheme. I just wonder why the interruption is happening. Shortly before reaching full charge. Never seen anything like this with the Pro1.

I wonder whether this is the same with all Pro1 X specimens. Did any of you see anything similar?

Edited November 4, 2022 by Rob. S.

[claude0001 1,240]

As far as I know, there is a switch from current-control (i.e. constant charging current) to voltage-control (constant charging voltage) at some point during the charge, which leads to a decreasing current as the charge reaches its maximum value. I thought that was standard for any Li-ion battery.

[EskeRahn 5,350]

21 hours ago, claude0001 said:

As far as I know, there is a switch from current-control (i.e. constant charging current) to voltage-control (constant charging voltage) at some point during the charge, which leads to a decreasing current as the charge reaches its maximum value. I thought that was standard for any Li-ion battery.

Usually that shift is invisble for the user though.

As we have in another thread, some new charging related thing cutting the scharging has been added starting from Android 11. It MIGHT be the same that is causings issues here?

[claude0001 1,240]

1 hour ago, EskeRahn said:

Usually that shift is invisble for the user though

Well, let's say they are not "apparent" during normal usage. But @Rob. S. is specifically using advanced tools to monitor the charging process. I guess, otherwise he would also not notice this.

Might be somethign else in the end, but especially the fact that the current decreases towards the end of the charge is pretty normal, I think. I see that also when charging my Pro1 using my solar-panel charger (which includes a built-in current gauge).

Edited November 5, 2022 by claude0001

[VaZso 1,988]

On 11/4/2022 at 6:20 PM, claude0001 said:

As far as I know, there is a switch from current-control (i.e. constant charging current) to voltage-control (constant charging voltage) at some point during the charge, which leads to a decreasing current as the charge reaches its maximum value. I thought that was standard for any Li-ion battery.

Right - basically Li-Ion batteries are charged at 4.2V with a certain limit of current (depending on battery capacity, charging circuit, etc).

So it has a current limit, let's say it is 1000mA - this current will be constant while voltage slowly increasing till it reaches 4.2V... as 4.2V is the voltage limit, current will slowly decreasing to a certain level, let's say 100mA where charging process is declared to be finished.

That is the basic charging of Li-Ion batteries, however, there are also a bit different batteries (chemistries) and a bit different values.

The changeover from costant current mode to constant voltage mode is handled by charging circuit (not software-related), so it is not really a "hard" switch but a seamless result of the process.

So, it is a simple process:
- There should be a 4.2V supply which should not be higher
- There should be a current limit
- If charging current goes below a certain value, we are done

[Rob. S. 1,616]

Thanks @all for the interesting and insightful input!

I'll try and see how the Pro1 behaves in comparison. 

Any recommendations for an app that would record charging power/current over time?

I wonder whether it might be possible to somehow make the Pro1 X refrain from that short interruption just a few minutes before fully charged...

Edited November 6, 2022 by Rob. S.

[EskeRahn 5,350]

6 hours ago, Rob. S. said:

Any recommendations for an app that would record charging power/current over time?

I use 3C All-in-one toolbox, he also got the battery manager as an isolated product. Been using it for many years.
Got some blah blah here