How best to find the "best" small solar panel of a particular size?
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A few boards arrived and a couple are assembled
The board charges four 1.5F 2.7V super capacitors. It also provides a boost circuit with 3.45V output on main and sub outputs. It works down to 180mV and provides 3.5mA for 30 minutes. I'll report on leakage.
There are two outputs main and sub. Main is on all the time and sub is switched with high signal on the mode connector.
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A few boards arrived and a couple are assembled
The board charges four 1.5F 2.7V super capacitors. It also provides a boost circuit with 3.45V output on main and sub outputs. It works down to 180mV and provides 3.5mA for 30 minutes. I'll report on leakage.
There are two outputs main and sub. Main is on all the time and sub is switched with high signal on the mode connector.
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@gohan if not you could add.... wait for it.... a capacitor. (Weak, I know, but I couldnt resist)
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Noise isn't bad at all. Surprisingly. It is no bigger than the background noise when no input is connected.
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@ceech very impressive! I really like:
It works down to 180mVthe boost to 3.45V works until the board voltage (between pin 5 and GND) goes down to 180mV?
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@alexsh1 Yes, the boost converter works down to 180mV. In other words, it can almost completely discharge capacitors.
@ceech Which brand of caps you are using?
I may be interested in this board too.I am currently running your other board with two 10F caps in a test mode with a sensor. Do not have much time for it now, most likely will report in September about my findings.
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@ceech Which brand of caps you are using?
I may be interested in this board too.I am currently running your other board with two 10F caps in a test mode with a sensor. Do not have much time for it now, most likely will report in September about my findings.
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Here is a link to openhardware page.
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Unfortunately it's not that easy, it depends on the type of "noise" created by the booster so one type of capacitor is better than another, a low pass filter may be needed.
@gohan
If it became an issue, you could turn off the boost converter while doing the radio receptions, and then turn it back on. Unless you were in some sort of continuous receive mode, which would drain things pretty quickly anyway. -
@ceech They are very good - I ordered a few myself.
Have you looked at using a flat super caps?
http://sigma.octopart.com/17606633/image/Maxwell-Technologies-PC10.jpg -
@alexsh1
See if you can find something you like on Digikey. They categorize by active, obsolete, and discontinued. -
@NeverDie Digikey is good, but too expensive for me. I have to order minimum £33 to have a free delivery.
I still may use them as the search engine only.
Thanks for heads up -
I've been following this thread and have bought a variety of little panels to experiment with.
These 5.5v 4F 'supercaps' have arrived in the post and I'm not sure how I should test them.
For now I would just like to see how well they hold a charge. What's the best procedure to test them?
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I've been following this thread and have bought a variety of little panels to experiment with.
These 5.5v 4F 'supercaps' have arrived in the post and I'm not sure how I should test them.
For now I would just like to see how well they hold a charge. What's the best procedure to test them?
@xgarb
I wish there were standard tests that were widely used, but there don't seem to be. You might try holding it at its rated voltage for 72 hours, then remove power and check its voltage after 24 hours with no charging to get some idea as to what its leakage is. These tests only mean something if you compare them against a capacitor that you like though. Then maybe it will tell you whether it's better or worse.The only test that really matters is how it performs in your use-case.
