Many old phones do not provide real current mA, thus the app is calculating it based on % changes.
For example using a 1500mAh capacity battery, a 1% change over one hour = 15mA. a 2% change over 30 minutes = 60mA, a 1% change in 5 minutes = 180mA.
When % is not changing the estimated mA is updated according to the last value.
If current mA = 60mA, and % remains unchanged for 30 minutes, this means current mA <= 30mA, hence the estimated mA is updated accordingly.
Please check how accurate estimated mA is.
