11-23-2014 08:56 AM
1. Hi, I turned my phone off at 15% to charge it and it took 1 hour and 28 minutes to charge to 100%. Once I turned it on, it only showed 98% charged. Just wanted a little more explanation on this fast charging method. Why it showed 100% and when powered on immediately 98%.

USMC97
11-22-2014 03:37 PM
2. 1) That's not "fast" charging. The normal max charge rate for lithium batteries is 1C - which means that if the phone can accept enough current you can fully charge a battery from 0.1% to 100% in 1 hour (plus inefficiency - no energy conversion process is 100% efficient in a universe with entropy), so 1.5 hours for an almost full charge (from 15%, not from fully discharged) is a normal charge rate. A fast charge would be 15 minutes - which is just a way to increase the sales of new batteries. It may be nice to be able to get 8 hours of charge into the battery in 15 minutes, but unless the battery is rated at 4 times the power that the phone uses in 8 hours (which would be about 12,000 mAh in most phones), it's cooking the battery into an early grave.

The Nanyang Technological University in Singapore recently (last month) announced a different lithium technology that allows very rapid charging, but as of now a) the battery to power a cellphone would be MUCH larger than a cellphone and 2) it would cost more than the most expensive cellphone. (And, given that the life expectancy is about 20 years, it probably will never see the inside of a cellphone - it's being developed for electric cars).

2) When the phone says 100%, the battery may or not be at exactly 100% charge. The phone estimates the state of charge by the voltage, which is about the most inaccurate way to do it - but it's cheap. (Only a chemical analysis of the battery - after taking it apart, which destroys it - can tell you the exact state of charge.) Let it charge until it indicates 100%. Then let it sit without charging for about 5 minutes. Then charge it again for 15 minutes. (It should actually sit for 24 hours before charging - but the fact that reality isn't very practical doesn't alter reality, and no one is going to sit with a dead battery for 24 hours every time the battery needs charging.)

3) Letting the battery run down to 15% on rare occasions is okay - it won't impact much on the life of the battery - but for maximum battery life it should be charged when it's down to about 40%-60%. Battery University - How to Prolong Lithium-based Batteries.
11-22-2014 04:08 PM
3. 40 to. 60% Never heard of that, but it does make some sense. Most people say let it nearly drains or around 15%. I get around 2 days on a full charge which i don't really use my phone to aggressively. Again thanks for your information.

USMC97
11-22-2014 04:26 PM
4. Most people say let it nearly drains or around 15%.
Put it on a charger whenever it is convenient. Like every night overnight.

If you think the battery gauge is way off, then you might try a full discharge/recharge cycle.
11-22-2014 05:42 PM
Put it on a charger whenever it is convenient. Like every night overnight.

If you think the battery gauge is way off, then you might try a full discharge/recharge cycle.

This.
11-23-2014 03:47 AM
6. Hi, I turned my phone off at 15% to charge it and it took 1 hour and 28 minutes to charge to 100%. Once I turned it on, it only showed 98% charged. Just wanted a little more explanation on this fast charging method. Why it showed 100% and when powered on immediately 98%.

USMC97
It is fast charging until about 75%,then the charging tapers. Basically expect 0-75% in 50 minutes, 76%-100% in 50 minutes.

I posted the charging profile here:

http://forums.androidcentral.com/sam...g-profile.html

You can download battery monitor widget or similar from the play store to log the battery charging profile to see what you are getting, but it seems inline with what I see. Going from 0-15% would be 9 minutes more so you are at 97 minutes for a full charge. Samsung states 100 minutes for a full charge, so you are on target. Further discussion on that here :

http://forums.androidcentral.com/sam...0-minutes.html

Sent from my Verizon Samsung Galaxy Note 4
11-23-2014 08:56 AM
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