[Windows Phone 7 General] Magpir:
on HD 7 , u cannot bump charge while its off...

the bump charging is different from android phones

If u do it from 20%.. u will get some where to 90- 95% capacity because the temperature limit is not reached earlier for the phone to do charge termination. if u charge yr phone from 0% ,, it gets pretty hot and the charge terminates before reaching 100%. thats the reason why the battery is only charged to 80% because of the temperature which makes the battery prematurely cut off charging.so u need to leave it for 6 hours or more when doing a full discharge or charge cycle.

because from 20% - 80% , in some phones the charge goes linearly, and then tapers off for the remaining 20% . We r unsure if this applies to the HTC, but probably for the iphone, it uses such a technique...to maintain a decent tolerable temperature..

the phone thinks that its to charge only 80%. so from 20% if u charge it, it will hit 90- 100 %. the on and off method just makes it up for the battery discharging itself to 80% caused by battery hysteresis...because there is the remainder of the 20 % not fully charged but partially charged. the OS battery indicator will drain down to 80% to correctly reflect the charge level. so u need to bump charge it

battery hysteris is a common thing in chargers that use 1.0C like the HTC HD7 . imagine pouring a beer into a mug...80 % of it is beer while the other 20% is beer foam..this beer foam will soon disintegrate fast leaving the beer only . this is why yr phone battery indicator drops when plugged off the charger. there are a few variations of this

a)phone only charges 80% ( timer based) in whichever scenario whether its from 0 % or 20% ( some HTC android phones). cuts off charging completely at 80%

b)Phone charges to 80% and taper /trickle charges remainder of 20% with a temperature limit determining the cut off point resulting in full 100 % (iphone).

c)Phone charges in a manner A) and b) , which is the highly likely the HD7 eg. 60 % full charge, 20% ( taper charge) = 80 %, remainder 20 % overcharge compensation and battery indicator of the OS showing 100 %. u will see the beer and foam effect here

we r unsure which way the HD7 battery charges. So the best thing is to charge it from 20% and bump charge it at 100%. this will take care of all 3 scenarios.

Notes below to consider:

Charging Rates

Batteries can be charged at different rates depending on the requirement. Typical rates are shown below:

Slow Charge = Overnight or 14-16 hours charging at 0.1C rate

Quick Charge = 3 to 6 Hours charging at 0.3C rate

Fast Charge = Less than 1 hour charging at 1.0C rate

Charge Termination

Once a battery is fully charged, the charging current has to be dissipated somehow. The result is the generation of heat and gasses both of which are bad for batteries. The essence of good charging is to be able to detect when the reconstitution of the active chemicals is complete and to stop the charging process before any damage is done while at all times maintaining the cell temperature within its safe limits. Detecting this cut off point and terminating the charge is critical in preserving battery life. In the simplest of chargers this is when a predetermined upper voltage limit, often called the termination voltage has been reached. This is particularly important with fast chargers where the danger of overcharging is greater.