At first, I was after crazy accuracy and fast sampling too, but in real life you can crash spreadsheet programs with few 10k lines of log..

Then there are 86400 seconds in a day and most of us use ~fullhd monitors, so 1920 pixels for your graph to see on one go. That makes 45 seconds per pixel (for a day). There might be some cases when you are willing to zoom in to your results, but mostly even that 10 sec interval is way more than i need (but as libreoffice calc can work with it, i wont be changing to 1 min ;) )

@GregS : Is your example normal DC measurements or something like PWM or other “spiky” stuff? Some random spikes wont really add up to Wh and PWM would get averaged, so if the Wh value at the end is the thing youre looking for, you should be ok.. Or i am completely wrong and your experiment is measuring how much energy you would get from lightning bolts and your values would be either zero or infinity ;) .. Even then, mooshimeter is right tool for you, as you can be BLE-range away (or anywhere with teamviewer-setup etc) if you happen to be watching live values when it hits your experiment ;D