Sent from my Galaxy Nexus using XDA
Let's say for example your phone is a stock 1750mAh (milliampere-hours) or 1.75Ah (ampere-hour) battery. A full charge will carry 1750mAh (1.75Ah). So 1% of 1.75Ah = 0.0175Ah. If you time how long it takes for you battery to charge 1% (i.e. start timing from the second you see it change and stop timing when you see it change again), and turn that many seconds into hours (i.e. x seconds * 1 minute/60 seconds * 1 hour/60 minutes), you can divide 0.0175Ah by that time "x hours," then you will have your charger estimate.
For example, I just timed myself on my stock charger. (Also I have the 2100mAh extended battery).
Took 50 seconds to charge 1% (went from 5% to 6%). So 50 seconds * 1 minute/60 seconds * 1 hour/60 minutes = 0.013888 hours.
0.021Ah/0.013888h = 1.512A or 1512mA, thus my phone is taking 1512mA from my charger.
***Note*** This will not be ENTIRELY accurate as you have the screen on to time how long it takes to charge 1%, and thus will counteract the charger. Also, this will work best when you have a battery percentage lower than 50%.
You are assuming (1) the charging curve is linear and (2) the percentages are accordingly assigned linearly. Do you have any information to back up these assumptions?
Your method may not be valid unless you are certain about these assumptions. For example, most gas gauges in cars are not linear like you would expect them to be either.
For the Touchstone Mod users:
Prior to Chad's kernel modification the Galaxy Nexus was only able to draw ~430 mA through the Touchstone. For some power users, this was not enough to keep up with heavy usage that included Navigation, 4G, and streaming music simultaneously. Reports had the phone either just barely maintaining its charge % or even slowly losing a couple % points per hour.
After applying Chad's kernel modification the Galaxy Nexus is drawing ~650 mA. An improvement of ~50%! Now the bad news: 650 mA is not as much as you can get from an appropriate wall charger. The limitation at 650 mA appears, in my opinion, to be the Touchstone itself. The Touchstone's supply voltage drops to 4.5V when drawing ~650 mA and the phone stops trying to pull more. This is a limitation of the amount of energy the Touchstone was designed to transfer.
The real question, is if 650 mA is enough to charge the device under the power user conditions I described earlier. Hopefully it is. I do not live in a 4G area so I hope you will all test and report back here.
Thanks again Chad!
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