Calibration - measured vs total mAh

Battery Monitor Widget produces 2 mAh values representing the total capacity of the battery.

The calculated mAh is derived from the specifications/reference data entered manually (original mAh, mV range) and compared to actual mV range from history file.

It is best to run a charge/discharge cycle to produce the initial reference data and compare the change over time.


The measured mAh is the average sum of all charge/discharge measured by the app during the past charge/discharge cycles. This should show a realistic value of actual battery capacity.

It will get more accurate if the app is monitoring while the charge/discharge cycles are being produced.


Proposed Steps:

1- Run a charge/discharge cycle (between <5% and 100%)

2- Update the reference data with measured mV range and mAh specification from manufacturer

3- Run more charge/discharge cycle

4- Check total mAh evolution and adjust reference data

5- Use phone as you please.

6- Run a charge/discharge cycle

7- Check calculated mAh evolution which should reflect battery aging

8- Compare with measured mAh and adjust reference data and stored data

9- back to 5


Important notes:

1- This screen is still experimental and produces data to get a view on battery quality and aging

2- To get more precise measured results, the charge or dischage cycles must be continuous with the app logging all measures. Charging the phone while completely off will prevent accurate calcuations.

3- Total mAh (calculated) will be more accurate when specifications/reference data are accurate. This total mAh can be used to measure the actual battery aging and the reduced capacity over time.



Original is what you define a battery to be (from specs).

In-use is what you define in monitoring settings (or from the original mAh when switching batteries).

Measured mAh is what the app has measured from full charge cycles recorded in the battery history file.

Estimated mAh used to be named 'Measured': On phones with estimated mA, the mAh is estimated too. On phones providing real mA, the mAh is measured.


Now, I plan to add a new user-defined paramter: The charger (AC only) capacity. This will allow the app to make appropriate corrections to estimated mA and mAh!


If mA is constantly above charger capacity, then the actual in-use capacity is definitely incorrect. This is mostly visible charging from 0% to 50%. A few pikes above charger capacity is ok considering the % reported can generate a large error margin. (wish we could get a xx.yy% precision!).


For example, my 1Ah charger produces this:

- with a stock battery (1750mAh) from 0% to 50%: 1212, 1083, 384, 1214, 610, 828. This looks ok to me.

Charge time: 2h40m!

- with an extended battery (2300mAh) from 0% to 60%: 1584, 1438, 1536, 1234, 1345! This obviously isn't right: the battery is over-rated and is more like a 1500mAh or so!

Charge time: 1h45m!


Soon, the app will be able to tell you this! ;)

Your phone, like most HTC devices provides real mA measures, so there's no need to compare charging measures against the charger capacity.

Android does not provide control over the battery technology, though it usually reports the technology in use (displayed on main screen). If it does change, then it's probably hard-coded in the kernel (?).

As for the actual meaures, please send a support request (with a note about this thread), I will be able to check the various measures. There might be a mA measure that's more accurate, though charging measures are usually right on.

Actual calibration is an internal process managed by the battery IC (integrated chip), not much that can be done for that.

The app calibration screen helps run charge/discharge cycles to get the battery calibrated and measures actual battery capacity.

Your phone providing real measures, results are usually very accurate. Note that the 10 minutes history logging is not a problem, the app actually measures mA every minute and provides an average over 10 minutes.

You could try a 1 minute interval while running a full charge cycle for more accurate results, but you'll need to wipe the history to avoid conflicts between old/new cycles. Note however that you will probably not get "better" results. Better in closer to what you wish.

The stats file can indeed be deleted by BMW, but you need to be rooted.


If the app measures 1933 instead of 2000, that's a 3% loss. To get the most of the battery I can only suggest to try this:

- Fully discharge the battery, restarting the phone unplugged until it won't restart.

- Fully charging the battery, and letting it charge for 12 hours.

This will maximize/optimize the % and mV range to obtain the best results.

I don't think the battery lost capacity yet, except if it was charging while above 70% and heating (playing a 3D game for example).

The problem is often the battery IC which will shutdown the phone before 0% (or 3200mV) or not charging up-to 4200mV (true 100%).