Galaxy S3 Intermittent Charge Rate

[Android Central Question]

Something strange can happen with Galaxy S3 charging - I have 2 phones - I9300, Android 4.3, not rooted. Sometimes there is intermittent slow charging or even discharging with phone powered off. To better understand what is going on I installed the Galaxy Charging Current app - this has proved useful to monitor the charging current (with phone powered on). The original Samsung chargers are capable of a high charge current and poor leads or contacts can be detected by monitoring the current using the app.

I am confident that I have good chargers, leads, micro-USB sockets and batteries yet the S3 charge rate can be intermittently slow. The random problem appears to be within the S3. An odd thing is that if the charging current is found to be low, e.g. at 100mA, and the charger is switched off for say 10 seconds, then back on again, the current can be very much higher and remain at or near this higher level (800-1000mA). If the current has later found to have dropped the procedure can be repeated - this effect is quite separate from the short-term high current immediately after connecting a charger.

Do we have any information how the charge current is controlled in the S3? Is a battery charge controller IC used (as might be expected?) or is there some software running while the phone is charging but powered off? Any thoughts on what might be going on here?

 

[Rukbat]

There's a hardware controller inside the phone. (The "charger" is just a power supply.)

Switch batteries from one phone to the other and see if the problem follows the phone or the battery. (If it follows the battery, I don't have to tell you what the problem is - and you don't have to do any more work to find it.) Slow charging if it's not a bad charger, bad cable or bad microUSB connector on the phone, is usually a bad battery.

If you need more help, join the Android Central community so you can post to this thread.