How can I find the Time for specific values of Voltage (with a small tolerance)?

Hi,

I want to extract an Indirect Health Indicator (IHI) from the below plot.

How can I find the Time for specific values of Voltage?

For instance, for Voltage = 3.8 (with a small tolerance 0.01), what is the TIme?

Lithium - Ion Battery Data Set #5 by NASA Prognostics Center of Excellence Data Repository.

load('B0005.mat');

% Cycle 1
Cell_Time_1        = B0005.cycle(2).data.Time;                      % Time (seconds)
Cell_Voltage_1     = B0005.cycle(2).data.Voltage_measured;          % Voltage (V)
Cell_Temperature_1 = B0005.cycle(2).data.Temperature_measured;      % Temperature (T)

% Cycle 30
Cell_Time_30        = B0005.cycle(82).data.Time;                    % Time (seconds)
Cell_Voltage_30     = B0005.cycle(82).data.Voltage_measured;        % Voltage (V)
Cell_Temperature_30 = B0005.cycle(82).data.Temperature_measured;    % Temperature (T)

% Cycle 60
Cell_Time_60        = B0005.cycle(198).data.Time;                   % Time (seconds)
Cell_Voltage_60     = B0005.cycle(198).data.Voltage_measured;       % Voltage (V)
Cell_Temperature_60 = B0005.cycle(198).data.Temperature_measured;   % Temperature (T)

% Cycle 90
Cell_Time_90        = B0005.cycle(313).data.Time;                   % Time (seconds)
Cell_Voltage_90     = B0005.cycle(313).data.Voltage_measured;       % Voltage (V)
Cell_Temperature_90 = B0005.cycle(313).data.Temperature_measured;   % Temperature (T)

% Cycle 110
Cell_Time_110        = B0005.cycle(431).data.Time;                  % Time (seconds)
Cell_Voltage_110     = B0005.cycle(431).data.Voltage_measured;      % Voltage (V)
Cell_Temperature_110 = B0005.cycle(431).data.Temperature_measured;  % Temperature (T)

% Cycle 140
Cell_Time_140        = B0005.cycle(545).data.Time;                  % Time (seconds)
Cell_Voltage_140     = B0005.cycle(545).data.Voltage_measured;      % Voltage (V)
Cell_Temperature_140 = B0005.cycle(545).data.Temperature_measured;  % Temperature (T)

Discharging Voltage Curves with Different Cycles

figure; hold on;
plot(Cell_Time_1, Cell_Voltage_1, 'LineWidth', 2);
plot(Cell_Time_30, Cell_Voltage_30, 'LineWidth', 2);
plot(Cell_Time_60, Cell_Voltage_60, 'LineWidth', 2);
plot(Cell_Time_90, Cell_Voltage_90, 'LineWidth', 2);
plot(Cell_Time_110, Cell_Voltage_110, 'LineWidth', 2);
plot(Cell_Time_140, Cell_Voltage_140, 'LineWidth', 2);
title('Discharging Voltage Curves with Different Cycles');
legend('Cell (1st Cycle)','Cell (30th Cycle)','Cell (60th Cycle)','Cell (90th Cycle)','Cell (110th Cycle)','Cell (140th Cycle)');
xlabel('Time (Seconds)');
ylabel('Voltage (V)');
axis auto;
grid on;

Extract Indirect Health Indicator

%

Answer 1

[Walter Roberson]

find(abs(data-target)<=tolerance)

Or ismembertol()

[Bob]

Thanks for your answer.

I don't understand how to use this one

find(abs(data-target)<=tolerance)

[Walter Roberson]

match_Times = Cell_Time_1(abs(Cell_Voltage_1-3.8)<=0.1);

Note that in general there can be more than 1 result -- if you were testing for 3.5 for example then you could get the self-recharge matches too.

[Bob]

Thanks again for your answer.

If I correctly understood, this is what I am looking for.

I tried to narrow down the tolerance but it doesnt seem to work but I am ok with the result.

IHI3_Cycle_140_High = Cell_Time_140(find(abs(Cell_Voltage_140-3.8)<=0.005))

IHI3_Cycle_140_Low = Cell_Time_140(find(abs(Cell_Voltage_140-3.5)<=0.005))

IHI3_Cycle_140 = abs(IHI3_Cycle_140_High(1)-IHI3_Cycle_140_Low(1))