I was only working with charging. For discharge, you can do 1-(charge percentage). So, for a 1 Tau discharge, the percent of charge remaining is 1.000 - 0.632 and get a remaining charge of 36.8%.

I modified the script above to print the discharge voltage percentages as well.

`Charge Voltage`

% Tau = 0 Percent Charge = 0.00%,

% Tau = 1 Percent Charge = 63.21%,

% Tau = 2 Percent Charge = 86.47%,

% Tau = 3 Percent Charge = 95.02%,

% Tau = 4 Percent Charge = 98.17%,

% Tau = 5 Percent Charge = 99.33%,

% Tau = 6 Percent Charge = 99.75%,

Discharge Voltage

% Tau = 0 Percent Charge = 100.00%,

% Tau = 1 Percent Charge = 36.79%,

% Tau = 2 Percent Charge = 13.53%,

% Tau = 3 Percent Charge = 4.98%,

% Tau = 4 Percent Charge = 1.83%,

% Tau = 5 Percent Charge = 0.67%,

% Tau = 6 Percent Charge = 0.25%,

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