How to increase the battery capacity beyond 3000mAh for battery profiling?

[Mike@PebbleStack]

Hi,

I understand it is possible to profile a battery larger than 3000mAh?  That said I've tried to modify profileSettings.json but the nPM PowerUP v1.3.1 seems to ignore the value and default to max 3000mAh.

Before I waste many hours will the incorrect value in the config file impact the profile outcome?

rgds...mike

[Mike@PebbleStack]

At least it didn't stop at 3000mAh!

It's a 5000mAh battery that I'm planning to use on a prototype device.

Based on this performance I'm guessing it will need to run for another 24 hours, I'm guessing the estimate is based on the incorrect value.

[Robin M Saltnes]

Hi, 

The capacity setting in the battery profiling menu only affects the discharge rate. A larger than selected battery will still fully discharge but at the same rate as a 3000 mAh battery would, meaning a longer total discharge time. The profiling process will also estimate the actual capacity of the battery during the profiling process. This number will be available to you after the process have completed.

The limitation in capacity for battery profiling is the charger timeout of the PMIC, which is 7 hours. So if you're using the full charge current of 800 mA, you could potentially profile a battery that's 800 mA x 7h = 5600 mAh. Not accounting for slower charging during the start and end of the cycle. 

br, 

Robin

[Mike@PebbleStack]

Hi Robin,

Thanks for the update.

So, does that mean as long as the battery is charged before profiling we can essentially profile any capacity battery? As long as we're willing to live with the discharge capacity of the Fuel Guage Board and the duration that implies.

For this test I set the current to 500mA in the charger but I'm not sure if it's this setting that is used or whether the profile charging is a function of the capacity setting?

I've either lucked out by charging the battery first and hence skipping the initial profiling charge sequence.

Or because the charger is set to 500 mA the profiling sequence will fail after 2-3 days due to the PMIC timeout.

rgds...mike

[Robin M Saltnes]

Hi, 

yes, that is a viable workaround, as long as you only profile one temperatue per session and make sure the battery is charged above a certain level between each profiling session. You can do this and still combine profiles from multiple sessions into one model after the fact. 

The current you selected is the current that is used for charging during the process, and the discharge current is a function of the selected capacity. 

The screenshot you provided is showing, altough not explicitly stated, that the battery was still discharging at the point of taking the picture. As long as you've only selected to profile one temperatue this should complete normally.  

br, 

Robin

[Mike@PebbleStack]

Thank you, that answers all my questions and yes, I did select only one temperature to minimise the chance of it getting interrupted.