Electronics > Power/Renewable Energy/EV's
Solar Panel + Diode + Supercap
Undweeber:
hi everyone,
I have got a little calculator sa3515s4 solar cell, it is able to power a calculator that requires 1.5V button cell to work.
I also have a supercapacitor I want to try charging with this solar cell just for experimental purposes, no plans to do anything what so ever yet.
Question: Is it dangerous for supercap to be directly hooked up to the solar cell? The discharge on this beast is 60A or a million A. could this damage the tiny solar cell?
Problem:
1. When I charge supercap with DC power supply, i do not use any diodes, and everything seems fine, the power supply handles the feedback voltage like a champ, so does my PC when I use USB power.
2. Solar cell does not have any circuitry to protect it from 90A feedback from the supercap so I am worried that the solar cell will fail killing itself while charging the supercap.
3. I have tried using a small diode with the DC power supply while charging the supercap, but that diode got so hot that i burned by finger, I have a beefy microwave oven diode that I could use, would that be advisable?? why did it heat up?
4. The solar cell can power a 5mm white LED directly from light, but when i put the same small diode between LED and solar cell, the light coming out of LED is much dimmer, why is that?
Give me some feedback please
ahbushnell:
As long as the capacitor is not charged when you connect to the solar cell I don't think it will be a problem.
fourtytwo42:
--- Quote from: Undweeber on May 13, 2018, 07:30:29 pm ---Problem:
1. When I charge supercap with DC power supply, i do not use any diodes, and everything seems fine, the power supply handles the feedback voltage like a champ, so does my PC when I use USB power.
2. Solar cell does not have any circuitry to protect it from 90A feedback from the supercap so I am worried that the solar cell will fail killing itself while charging the supercap.
3. I have tried using a small diode with the DC power supply while charging the supercap, but that diode got so hot that i burned by finger, I have a beefy microwave oven diode that I could use, would that be advisable?? why did it heat up?
4. The solar cell can power a 5mm white LED directly from light, but when i put the same small diode between LED and solar cell, the light coming out of LED is much dimmer, why is that?
Give me some feedback please
--- End quote ---
1. A power supply normally has a rectifier following the transformer and this prevents any reverse current flow, not sure what you mean by USB power.
2. Solar cells are by there nature diodes so they will not conduct reverse current flow unless you exceed there reverse voltage rating that is usually considerably above VOC.
3. That sounds like you were overvoltageing the supercap causing a large current to flow, very dangerious. Microwave oven diodes are very high voltage low current diodes and not suitable. You want a standard GP diode like an 1N4001
4. The diode introduces a voltage drop, usually in the range 600-1000mV so the LED becomes dimmer. It is normal to include a current limiting resistor in a LED circuit however in this case I think the solar cell is self limiting at a low enough value not to burn the LED.
Do you posess a DVM ? that would help you understand whats going on :)
NiHaoMike:
Use a Schottky diode for low voltage drop.
metrologist:
--- Quote from: fourtytwo42 on May 14, 2018, 08:10:24 am ---1. A power supply normally has a rectifier following the transformer and this prevents any reverse current flow, not sure what you mean by USB power.
2. Solar cells are by there nature diodes so they will not conduct reverse current flow unless you exceed there reverse voltage rating that is usually considerably above VOC.
3. That sounds like you were overvoltageing the supercap causing a large current to flow, very dangerious. Microwave oven diodes are very high voltage low current diodes and not suitable. You want a standard GP diode like an 1N4001
4. The diode introduces a voltage drop, usually in the range 600-1000mV so the LED becomes dimmer. It is normal to include a current limiting resistor in a LED circuit however in this case I think the solar cell is self limiting at a low enough value not to burn the LED.
Do you posess a DVM ? that would help you understand whats going on :)
--- End quote ---
1. probably 5V from a USB port.
2. I'd like to know more about that. I thought SP would discharge a connected cell.
3. I'm trying to picture this - a very small calculator solar cell. The cap would have to a very low voltage rating? I still don't see such a small solar cell making enough energy (current) to heat a diode enough to burn flesh. I mean, if...
4. the solar cell has a very limited current output.
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