Integrate to find area under curve (compute battery amp.hrs) using Python / Scipy Trapz

Question

I am trying to compute the battery usage in Ah used by a system. I have the data loaded in pandas with a time index and a battery current in mA. Example data frame below:

TIME                    Current
2020-08-07 08:15:54     1.704000
2020-08-07 08:16:04     NaN
2020-08-07 08:16:14     0.852000
2020-08-07 08:16:24     0.852000
2020-08-07 08:16:36     5.965000
                         ...    
2020-08-07 09:14:42    95.446999
2020-08-07 09:14:52    95.446999
2020-08-07 09:15:02    94.595001
2020-08-07 09:15:12    NaN
2020-08-07 09:15:22    98.856003

Currently i am trying to do it like this:

from scipy.integrate import trapz
    def battery_usage(df):
        df = df.dropna(subset=['Current']) # remove row from df when 'Current' is NaN
        amphrs = trapz(df['Current'], x=df['Current'].index , axis=0)
        amphrs = ((amphrs*1E-9)/3600)/1000) #Try to convert mA.ns to A.h
        return amphrs

The Trapz function is returning a timedelta64 in nanoseconds and I'm not too sure what to do with that

Answer 1

结果实际上似乎是正确的，我假设它知道 x 轴单位是时间（ns），但不知道“当前”系列的单位，因此 ns x unitless 是 ns。