I have also had the same results with a 470uF one. This can be expressed as : so that (1) R dq dt q C dq dt 1 RC q which has the exponential solution where q qo e qo is the initial charge. The market for portable solar powered electronic devices continues to grow as consumers look for ways to reduce energy consumption and spend more time outdoors. What was interesting was that the original multimeter measured 0.46V, while the new one measures 0.51V, which seems to back up what you suggested since the new multimeter likely has a different internal impedance.Īs for the capacitor types: 1uF tantalum cap is charging to over 1.2V but gets discharged before quickly when I connect the multimeter so I assume this is going to 1.6V because the 100uF aluminum cap is charging to 1.6V (although it takes a long time to get to that, 1.4V is much faster). a resistor, the charge flows out of the capacitor and the rate of loss of charge on the capacitor as the charge flows through the resistor is proportional to the voltage, and thus to the total charge present. I measured just about 50-60 nanoamps of current. What do you think ? I could be all wet, frequently am.Īfter making the original post I was able to get a much higher quality multimeter and test the device. When you measure voltage across your capacitor with such a feeble light sourceĥ0 nanoamps will charge 1 microfarad at 50 milllivolts per second, initiallyĪs capacitor voltage increases, the DMM steals current via its 10 megohm input impedanceĪnd at 1/2 volt it's stealing it all so charging ceases.Īnd when you disconnect the meter charging re-commences Here's what i think is the answer to your original question. You might need an electrometer to measure such feeble currentĪnd you didnt say how big is your capacitor When the output PV voltage hits Voc and the current falls to I0 (almost zero), the charging ceases. I wager you get about 0.5 volts/10 megohm = 50 nanoamps. to the reverse saturation current I 0 of the diode’s equivalent circuit. The super capacitor has the fastest charging time compared to all other. Try measuring the current your photocell makes by switching your DMM to lowest current range. photovoltaic source with a super capacitor storage system and sepic convertor. Then you can't knock loos a whole lot of electrons, can you ? The light source is very very dim - I'm using a tritium phosphor vial as the source with a tube of reflective foil around it to redirect some of light back into the cell.
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