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I have a 1 F double layer capacitor in a circuit supplying power to a micro-controller and an RTC circuit. I will be measuring the I(V) from 5 V to 0 V Is there a way to predict the discharge curve, V(t), from the I(V) curve?

By I(V) curve I mean measuring the current load at voltages from 5 Volts to 0 Volts in 1 milliVolt divisions. If I can do this in LTspice I am up for that.

I would like to do this with an arbitrary initial charge so I can do some what-if scenarios.

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You can use numerical methods to solve this. The derivative can be approximated by a delta. Here it is in Excel. You will need to substitute your I(V) data. You can use a lookup function for that.

For my example, the time interval is coarse, you will want to use a finer increment.

enter image description here

With "show formulas" enabled: enter image description here

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  • \$\begingroup\$ I was giving this a try but excel spent a lot of time doing the lookup for the calculations. I may try pushing it into VBA, a c or python program to crunch the data then import to excel for the graphing. \$\endgroup\$
    – user30884
    Sep 27, 2021 at 11:27

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