[AT&T Samsung Galaxy Note I717] taob:
This leads into the most interesting part for me. The charging current is controlled by the circuit in the phone, which appears to be done in software (i.e., likely some driver code in the kernel). This means there ought to be a way to specify how much power to draw, subject to the physical limitations of the hardware itself. All the cable tricks mentioned (shorting data pins, applying voltage to the shell, etc.) are just ways to signal to the OS that a higher-than-normal charging current is supported. Why not just ignore all that, and give us a widget button to toggle that on or off? Of course, there would have to be a disclaimer that you could fry your equipment if you're not careful, but I would love to see that. We should be able to take advantage of those 2A chargers for iPads and TouchPads and so on, without needing special cables or other hardware tomfoolery.

---------- Post added at 10:38 PM ---------- Previous post was at 10:14 PM ----------

If your Note consumes more than 1000 mA while running all of the above, you are probably out of luck. With everything turned on, I have seen my Note discharge at greater than 1 A, which means no charger will be able to keep up, because the Note itself will not draw more than 1 A via the micro USB port. The best you can do in those scenarios is to buy an extended battery and keep the net discharge rate as low as possible.

I think the worst-case scenario is around 1200 mA, although I have not confirmed this to my satisfaction yet. That means a net discharge rate of 200 mA. With the stock 2500 mAh battery, you will get roughly12.5 hours. With the Mugen 5400 mAh extended battery, that goes up to about 27 hours. That's with 100% screen brightness, 4G/LTE, GPS, BT, Wifi tethering, etc.

Here's the battery charge log during a trip earlier today. The important columns are the 4th (battery percentage) and the 6th (1/10 milliamps):

# time / source / temp / capacity / voltage / current

20120706-150540 2 348 48 3905000 10018

20120706-150640 2 350 48 3897500 10026

20120706-150741 2 355 48 3867500 10028

20120706-150841 2 361 48 3852500 10026

20120706-150941 2 368 48 3917500 10026

20120706-151039 2 369 48 3923750 9010

20120706-151139 2 374 48 3832500 9029

20120706-151239 2 378 48 3852500 9028

20120706-151338 2 382 48 3848750 9027

20120706-151438 2 381 49 3878750 9030

20120706-151538 2 384 49 3850000 9028

20120706-151638 2 384 49 3946250 10022

20120706-151738 2 381 49 3853750 10021

20120706-151838 2 383 49 3893750 10027

20120706-151938 2 384 49 3846250 10027

20120706-152038 2 383 50 3927500 10029

20120706-152139 2 388 50 3932500 10026

20120706-152239 6 390 50 3853750 5025

20120706-152339 6 395 50 3822500 5025

20120706-152439 2 407 50 3823750 10030

20120706-152539 2 409 51 3895000 10032

20120706-152639 2 412 51 3841250 10033

20120706-152739 2 426 51 3865000 10030

20120706-152839 2 437 51 3837500 10028

20120706-152939 2 444 51 3832500 10019

20120706-153040 2 449 51 3801250 10031

20120706-153140 2 454 51 3851250 10032

20120706-153240 2 466 51 3885000 10030

20120706-153340 2 465 51 3850000 10033

20120706-153440 2 463 51 3853750 10033

20120706-153542 2 473 51 3893750 10030

My script logs once a minute, recording the date and time, charging method ("2" = "AC power"), battery temperature, percentage remaining, voltage and inbound current. As you can see, the percentage slowly rises. This with 100% brightness, GPS, 4G, Wifi (but not connected) running Google Navigation. I did not have BT enabled, nor was I using mobile data (the map data is already cached).

I was testing out two new car chargers, which is why you see different charging rates. One is the Bracketron dual USB adapter, and the other is the Duracell 100W AC inverter. I used the Samsung USB cable for all tests. The 1A port on the Bracketron and the Duracell inverter paired with the Samsung AC charger both gave me 1000 mA. However, the Note only draws 500 mA when connected to the 2.1A port of the Bracketron, and nothing at all on the Duracell's USB port! :confused:

http://www.amazon.com/dp/B0056VNVV8

http://www.amazon.com/dp/B004U1Y3V2

But with the right combination, I am gaining about 1% battery charge every 5 to 10 minutes. This is also using the 5400 mAh battery... the stock 2500 mAh battery would go up about twice as fast, percentage-wise. It's not very fast, but at least it isn't discharging.

I will have a longer road trip in a couple of weekends (3 hours each way), where I will start with a fully-charged Mugen, and see where I end up when I arrive back home.