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.