First off, "drained the battery" and "normally" don't belong in the same sentence...you should avoid EVER (if possible), allowing the phone to completely "drain" the battery to the 0% level and self-power down. If it does so, you run the risk of exactly what you are dealing with now. These batteries are more fickle than batteries of the past and require a very involved and intense monitoring of charging and discharging rates/values in order to not send them into an irreversible state of "protection". That coupled with the current the phone requires simply to boot can cause a battery that is "discharged" to become unresponsive. Once the battery has been discharged below a certain current level the phone while trying to boot actually uses more current than the charger can supply while trying to also charge the battery. This results in the battery never actually getting any charge (or very little), and can remain in that state either indefinitely or for a very long time.
There are many potential "solutions" to this dilemma, but the most effective is a Motorola Programming Cable, a special version of the USB cable that applies voltage directly across an otherwise unused pin on the USB cable and essentially bypasses the charging circuitry on the phone, instead supplying voltage directly to the phone and battery without any sort of monitoring or protection for the battery. Using one of these cables can actually supply more current to the phone and battery than the phone itself is drawing, leaving an additional overflow that can then back-feed into the battery and slowly raise its current and voltage levels to a point where the normal charging circuitry can then resume normal charging.
An alternate method - which by the way is both opening the phone case and voiding your warranty, is to strip the micro-usb cable end off a USB charging cable and jumper the red and black wires directly to the respective positive and negative terminals of the battery itself. EITHER method should be done with EXTREME caution so as to not allow the direct-charging method to remain for long periods of time or unattended. BOTH methods should ONLY be allowed to "jump-start" the battery for periods of 30 minutes at a time, and with an attempt to go back to the normal charging method between jump-start attempts. Also, the "jumpered" charging method is dangerous since although the battery may have too little voltage or current to carry the load of the phone booting, it still has MASSIVE amounts of power remaining and if the terminals were to be shorted it could result in fire and/or explosion of the battery.
This all results from allowing the battery to drain to the point where the phone shuts itself off - a practice you should avoid at virtually all costs. The reason this happens is that the metering circuitry and battery's actual State of Charge (SOC), become, shall we say...out of sync. Characteristics unique to the Lithium Ion Polymer batteries and their discharge curve (the rate at which the voltages and current available change while being used), make it difficult for the metering circuitry to actually know with any real accuracy how much "usable" power is left in a battery at any one time.
The charging circuitry uses two key levels which are set as "flags" during the charging and discharging process to essentially mark the "goal lines" on the field, but as with any field, there is an "end-zone", where the battery can either be "overcharged" or "deep-discharged". Unless the meter can have an accurate representation of where the goal lines are (fully charged to 100%, and NEARLY depleted to 10%), it can't then do the iterative solutions along the way to relatively accurately indicate the SOC. This results in the real and suggested SOC levels to diverge and eventually be so far apart that the phone can misrepresent the levels and risk what you've experienced and all that you've read.
This happens over time, due to the way we both use and charge our phones. It just so happens that we are not in sync with the battery but instead we are sporadic with both our charging and discharging rates and times. This lack of uniformity "confuses" the meter and it begins "recognizing" various other SOC levels incorrectly as being the "Fully Charged", and "Discharged" SOC, and then using those incorrect level "flags" causes incorrect estimated remaining charge levels. Also, as batteries age, their ability to hold a charge changes. Imagine for a moment a Football Field with goal lines that moved, but the distance between each 10-yard line (percentage of charge), wasn't changed accordingly. The lines would still say 10, 20, 30 yards, etc., but the actual distance to the goal post (discharged level), would be shorter. So the field "seems" to be the same length, but you run head-first into the goalpost unexpectedly, far too soon and without warning and suffer a concussion!
The solution to the cause, which should be practiced about every 2-3 months, is to take the following steps (after we've successfully recovered the charging ability on your phone, of course);
1) Power the phone completely off (press and hold the Power button, choose "Power off"). This can be done at ANY remaining charge level, even if 100%.
2) Plug phone into STOCK USB charging cable and STOCK wall power adapter, and allow it to boot into "Charge-only" mode.
3) Allow the phone to charge the necessary time until either it displays "100%" on the screen when briefly tapping the "Volume" buttons, or when at least 3 hours (Droid Razr and most other phones), or 5.5 hours (Droid Razr MAXX/Droid MAXX, et. al.), has elapsed.
4) Disconnect from the charger and power up the phone normally.
5) Use the phone as you normally would, but taking care to use it until at least the point where it tells you to plug into the charger, but NOT to use it until it nears 0%. 10% is what I believe is the new "Discharged" level. That level is set to give you time to finish your phone call, save any work or emails you are composing, shut down your movie, etc., and then power down and find a charger BEFORE it reaches 0%.
6) Repeat steps 1 through 4, but this time you are DONE once you've completed step 4. From there you can charge and use your phone as you normally do, but repeat this 6 step process again in another 2-3 months.
By doing the 6 step process above, you are essentially telling the METER WHERE the GOAL LINES SHOULD BE based on the battery's TRUE SOC, and then the METER can more accurately ESTIMATE where the individual "1/10 of the field length" lines SHOULD BE painted and marked with their ACTUAL distances or levels in percentage.
I hope this football analogy works for most. It's the best I could come up with to keep it simple but effective.
Good luck! :biggrin:
