Tuesday, June 23, 2015

Using a Samsung 2A travel adapter with adaptive fast charging with MotoG : How does it behave? part 2 : more data

Materials and Methods
Trying to keep things objective
See Part one for for the tools used and limitations inherent to the method used.
A few precisions :
  • legend used in graphs:
    • Power-In (W) --> Power used by the samsung AC adapter
    • Power-Out (W) --> Approximated power delivered by the AC adapter
    • Out-disp (mA) --> Current displayed by Ampere App = Current received by the battery
    • Offset : +250mA (= Current used by the device idle, screen ON drain, wifi ON)
    • Offset (WifiOFF) : +160mA (= Current used by the device idle, screen ON drain, wifi OFF)
    • Out-real (mA) --> Current delivered by the AC adapter (out-disp + offset)
    • pm8226 T° (C) --> Temperature of pm8226_tz probe. (MotoG and MotoG 4G/LTE aka Falcon and Peregrine)
    • pm8110 T° (C) --> Temperature of pm8110_tz probe. (MotoE aka Condor)
    • Battery T° (C) --> Temperature given by battery probe
  • ...

Charging and Time
Monitoring battery charge and Current over time

Charging curve is pretty common with a linear charge until 60% and then the rate starts decreasing. Nothing special there.
Charging Current follows the same behavior, showing that the power regulator of the MotoG does its job correctly limiting charging current to safe levels.

Charging and Temperature
Monitoring pm8226 and pm8110 Temperatures and respective charging current over Battery charge

Before showing any graph, we should keep in mind that results are highly inconsistent, T° is directly related to the way device is really idle or not, things can vary from 46 to 57°C!
I had a peak T° of 57°C when using Youtube, twitter and a few services running while charging. Though this peak T° is quickly going down to 52°C and then stabilize at about 50°C back to idle state

Do not use your device for moderate to intensive tasks while charging it (with high power charger) or it will fry!

Concerning OFFline charging, i had no way to monitor, but power used by the AC adapter is still between 7.9 and 8.7W (like ONline charging. the Screen T° felt (the pm8226 module is behind the center of the screen) is as warm as online charging when pm8226 was at about 48°C; obviously a felt T° is not objective.

We can see that the adapter provides a fairly stable current (most variations might due to measurements inaccuracies.) until 60% of charge, then it drops (expected.). Though the power management module that is pm8226 is extremely HOT (50+°C!!) --> Why is that?
  • Doesn't it have an overheat protection? i'd love to investigate this...
  • Is the AC adapter output too powerful for it? No, as we see, the module is able to limit current in the end of charge so it should do it at any time.
  • Is the maximum Current accepted by the device to high for it? Motorola specifies the device to be able to charge with up to 1500mA, 1300 doesn't blow it up! I'm looking on a way to force a limitation to 1000mA and see if there are any improvements in T°

IMPORTANT : work hold on at this stage, i might continue it later. this article is published not to forget the already done part.

Saturday, June 20, 2015

Using a Samsung 2A travel adapter with adaptive fast charging with MotoG : How does it behave? part 1 : first overview

My old Sony-Ercisson 850mA charger is ageing and i needed a new and more powerful one. i Bought the Samsung 2A travel adapter with adaptive fast charging model EP-TA20EWEUGWW (white one, with French 2 pins male plug)
  • We can read everywhere that a charger will only provide what the device is capable to take, is that right?
  • Is that really safe to charge a MotoG (specified to be capable of charging between 550 and 1500mA by the manufacturer) on a 2A adapter?
In the way chargers work, it should be ok, but does the device really behaves the way it is intended to?

Materials and Methods
Trying to keep things objective
  • To monitor input Current:
    A wattmeter:
    It has a precision of +/- 1W that isn't precise at all, but this is only to roughly monitor the input current. ==> this inaccuracy will prevent me to give good efficiency predictions...

  • To "monitor" output current: Ampere
    the app is not meant to be accurate, the idea is only to have an approximation of the current delivered by the charger.
    • The device uses between 180 and 300 mA when idle, screen ON, wifi ON.
    • Ampere mesurements display current applied to the battery, not the one coming from the adapter; so we will add 250mA to the results (or 160 with the experiments without wifi).
    • Therefore if Ampere displays +1000 mA that would mean that the adapter provides about 1250mA and Battery gets 1000mA.
    • Considering previous experiments we can assume that the results are accurate at +/-100mA; this means that when Ampere displays 1000mA, the charger provides something between 1150 and 1350mA (displayed current +250 +/-100)
  • To monitor Temperature:
    Temperature is monitored with the pm8226_tz probe that looks like to be linked with the power manager of the battery -aka battery 'charger' when device is plugged to power source-
Chargers characteristics:
Sony: 5V 850mA
Samsung: 5V 2A or 9V 1.67A with fastcharging capable devicer (EP-TA20EWEUGWW)
For this first experiment the device was discharged down to about 50%

When results are so inconsistent that you cannot really conclude -_-'
Sony at 50% charge:
  • Input power: 6W +/-1
  • Output power: 3.75~4.75W (5V 750~850mA)
  • Efficiency : 54~95% (worst_case~best_case)
Samsung at 50% charge:
  • Input power: 8W +/-1
  • Output power: 6.35~7.35W(5V 1270~1470mA)
  • Efficiency: 70~105% (No, current is not coming from anywhere, this 105% is due to the +/-1W inaccuracy of the input wattmeter!)

As best case condition cannot be used, let's see for worst cases:
Samsung worst case is above the sony's worst case so we can at least say that this adapter is NOT LESS efficient in this specific condition [50% battery, room temp @21°C ...]. As i don't have enough data yet -and the worst monitoring tools available- i am not able to say that the Samsung Charger is more efficient.

When spare Watts become heat?

Sony at 50% charge :
Battery charging current was about 600mA meaning that the charger was providing 850+/-100mA, considering the charger cannot provide more than 850mA, the real value is somewhere between 750 and 850mA.
pm8226_tz T° is about 43°C, this threshold is never exceeded.

  • at 50% charge :
    Battery charging current was about 1120mA meaning that the charger was providing 1370mA+/-100 pm8226_tz rises up to 51°C until the 70-75% of charge are reached,
  • Then (70%+) current is limited to about 800mA and T° decrease slowly to reach 41°C at 80%.
  • At 89% current is only 400mA pm8226_tz only 37°C and the Input current is lowered at 3.2W.
  • When fully charged, idle and screen ON, the adapter still uses 1.9W from home circuit. which means that with an efficiency of about 70% the adapter provides about 226mA which corresponds to the device usage. When screen is OFF, the adapter input current drops under the watmetter detection threshold.

Here is a chart showing Charge Current and pm8226 Temperature against charging percentage.

Now, the questions are,
  • what happens before 50% ?
  • Does the adapter reaches the 1500mA that the device is theorically capable to handle?
  • Is the device really able to handle that much Current ?
  • How does the temperature increase if the device is NOT totally idle while charging?
  • Will the battery survive multiple full charge this way?
Some answers in a few days, after i tried and get more data -and hopefully not fried my device xD-.

Quick Update before the full article : my MotoG power management unit (pm8226) reaches up to 57°C when using it really little while charging, i don't think it is safe at this level of heat ...

If i had better tools, i would try to make accurate charts about :

  • pm8226 and battery T° (C) and Current (mA) against battery charge (%)
  • Battery charge (%) agaisnt time (min)
  • Charger efficiency (%) against Battery charge (%)
  • Monitoring surface T° with a IR camera
  • ...

Tuesday, June 9, 2015

CM12.1 : A few Drawbacks

I'm using CyanogenMod ROMs since the very beginning (started with a fork of CM6 called MiniCM6 by XDA Recognized Developer nobodyAtall).

Every CM version since then had more and more features, less and less bugs: the Sony-Ericsson X10mini (e10i, aka Robyn) started with the 'well-known' "SDcard safe to remove" reboot bug that crashed the device twice a day in the early miniCM6 ages...,
CM12.1 on Falcon (Motorola MotoG, XT1032) is far from this, a lot more mature, but still lacks a few things

CyanogenMod Logo
Some lacking Features and some issues

Here is a list of a few things that bothers me in CM12.1. Don't take it wrong, CM12.1 is nice and works pretty well, the following list is only a few "cosmetic" issues, user-experience related.

  • Expanded Desktop
    • Sometimes the nav bar doesn't show up when swiping up. (It needs to swipe down to display notifications, and then, nav bar shows up)
    • On some specific apps the nav bar is "ghost" meaning that once displayed (after swiping up) touching return buttons behaves as if the user had touched the content behind [like an ad........])
  • "Per App" Expanded desktop
    • Enabled for all is nice,
    • Per app settings is nice, -when "Enabled for all" is un-checked-
    • BUT why can't we make per app customisation, when "Enabled for All" is checked? that would help when the user wants the expanded desktop to be enabled for NEARLY all apps, but keeping a few apps with both nav and status bar.
  • 'The random Black Screen' with AmbientDisplay (with wave to wake, an pocket mode enabled)
    • In some rare cases, getting a notification wakes the device, but screen goes black (the only way to "fix" is force rebooting the device). Still no way to reproduce found yet,
  • LiveDisplay : Automatic settings
    • Automatic settings only work when location is enabled. A great addition would be to set time of start and time of end of 'night-mode' as whe can do with F.lux or RedShift for users that don't keep location enabled all-the-time.
  • LMK, is that really an issue?

Feel free to comment below, and i will update this article with your own feelings about the lacking features and the issues that bother you in CM12.1 (don't forget to tell your device if the issue is specific to a branch

For those complaining about Battery Life, don't forget to read this article ;-)