Curious if anyone has the same battery issue..My battery voltage charges to around 4260 with the phone off and charges to 4354.with phone on...anyone else noticing that with theres?
I had started to answer this earlier but never completed... This is a work in progress so until you see "In closing...", it's not done.
Battery charging is a strange animal, because it's not just voltage but also amperage (or current) that together comprise the battery's capacity. Voltage and current are hard concepts to explain, but I'll try to give it to you in layman's terms.
Voltage is sometimes described as pressure (or as I like to say, desire to flow from point to point). Current or Amperage is described as the volume or rate of flow. Sometimes it is described as the water pressure in a hose. With the hose closed, the pressure is the desire for the water to flow out of the hose through the closed nozzle. Once you open the hose's nozzle, then the water starts to flow, and then the rate of flow (gallons per minute), would represent the amperage or current. You can have voltage (pressure) without current (flow), but you can't have current (flow) without voltage (pressure). If there were no pressure (voltage), the water wouldn't flow (current), yet there can be measurable pressure (voltage) even when the nozzle is closed and there is no flow (current).
When charging a battery two things happen. First, the voltage being pumped into the battery is higher than the voltage the battery is at when its discharged, and even slightly higher than what the nominal charged voltage for the battery is when fully charged. Without a higher voltage, the battery wouldn't charge, since there would not be pressure to force the charge into the battery. In other words, a 3V battery level wouldn't take a charge from a 3V charger, but would begin taking a charge if the charger were 3.1V or more.
Second, there is the amount of current allowed to be forced into the battery. For us, it's limited to 750mAh, but on the chart below it's showing 1A (1,000mAh). Also, you'll notice the charging voltage starts down around 1V (as represented by the voltage legend on the right), but for our batteries, it starts at about 3V, so once again the chart is somewhat of a misrepresentation of our batteries.
While there is still more than enough capacity to take the full 750mAh of current, it will continue at that level. Meanwhile, the voltage is slowly rising. Once the battery reaches the nominal charged voltage (around 4.2V), the battery is now beginning to "fill out", and so what happens is the amount of current it will allow or absorb starts to decline (the line that slopes downward). With our chargers, the "Stage 1" charge portion is very long, since it's charging slower. Stage 2 is rather short by comparison. So somewhere near 90% of capacity, the charger steps down the voltage and slows the charging rate to allow the battery to gently fill the last 10%.
Eventually as the battery nears current draw that represents about 3% of capacity (even a fully charged battery will draw SOME current), meaning the battery is approaching 100% full (1,750mAh at about 4.2V for the RAZR, 3,300mAh also at about 4.2V for the MAXX), the charging system shuts down completely and then remains in a wait state until voltages drop to about 90% of maximum, indicating a partial discharge, at which point the charger kicks in again and "tops off" the battery back to 100%.
In all batteries that are being charged, once the battery has stopped charging, there is a period of "settling in" where the voltages will stabilize and reduce or "roll off" slightly. This isn't the same as self-discharge which happens over longer time-frames, but could be compared to the balloon relaxing a slight bit from right after it's having been filled. The pressure inside the balloon will drop slightly as the rubber relaxes and "gives" a little more. It's not a fair comparison but an analogy that can help to make sense of this. What really happens is some of the excess voltage helps the current to "settle in" and gives of itself in the process. It's small but enough to see.
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The question was, why does the battery seem to reach a higher voltage with the power on than with the power off. I can't say for sure, but this likely has to do with the "parasitic load" of the phone. Since the phone is also drawing current, it has the tendency to "fool" the meter into believing the battery is a bit larger than it really is, so the meter will allow the charger to continue charging at the higher voltage of Stage 1, rather than stepping down the charge rate to Stage 2, perhaps causing the voltage of the battery to rise beyond the 4.2V nominal that it's pegged to stop at. Another possibility is that even though it may have switched into Stage 2, it still doesn't see the signature 3% current draw that signals a full battery, since the phone is pulling current too, so the battery is unfortunately being over-charged as a result.
I've said it before, the most accurate way to get 100% charge is to do so with power off. This will allow the charging circuit and meter to accurately determine charge levels along the way and switch from Stage 1 to Stage 2, to Stage 3 (waiting), without risk of either over or under-charging the battery. Still, charging with power on isn't going to substantially over-charge the battery and so it's not going to place the battery at substantial risk of long-term lifespan reduction.