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WeatherShield + supercapacitor + tiny solar cell
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Topic: WeatherShield + supercapacitor + tiny solar cell (Read 2684 times)
HeneryH
Full Member
Posts: 229
WeatherShield + supercapacitor + tiny solar cell
«
on:
October 10, 2017, 04:55:51 PM »
https://lowpowerlab.com/2017/09/15/weathershield-supercapacitor-tiny-solar-cell/
Felix, I didn't see a way to discuss your blog post so I am posting here.
I'm confused by the voltage graph
I understand the gradual ramp down as the battery is consumed during darkness, but why such a short almost instant ramp back up to full charge? Shouldn't the voltage either ramp up or maintain full during the daylight hours?
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Felix
Administrator
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Posts: 6866
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Re: WeatherShield + supercapacitor + tiny solar cell
«
Reply #1 on:
October 10, 2017, 09:43:26 PM »
I think it might be how the sun angle hits my house siding where this glass block is. There's a peak during the morning hours. Then the sun moves above the house and that side is still brightly lit but not direct sunlight.
I can assure you this is not made up data
Notice towards the beginning there are 2 instances of the slope going down across 2-3 days. Thats when it was very cloudy/overcast and the cell just didnt provide much charging current.
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HeneryH
Full Member
Posts: 229
Re: WeatherShield + supercapacitor + tiny solar cell
«
Reply #2 on:
December 16, 2017, 02:29:12 PM »
I hot-gun glued the capacitor directly onto the back of the solar cell and soldered the diode and cap in-place.
The three parts I used. Total rookie guesses on these parts, I'll post results after a full day and night of statistics are collected.
SuperCap - $6.63 ea -
https://www.mouser.com/productdetail/581-scmt32c755mrba0
Solar Cell - $1.99 ea -
https://www.digikey.com/product-detail/en/seeed-technology-co-ltd/313070004/1597-1417-ND/5488049
Schottky Diode - $0.41 -
https://www.digikey.com/product-detail/en/on-semiconductor/1N5819/1N5819FSCT-ND/965482
«
Last Edit: December 16, 2017, 03:20:42 PM by HeneryH
»
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HeneryH
Full Member
Posts: 229
Re: WeatherShield + supercapacitor + tiny solar cell
«
Reply #3 on:
December 16, 2017, 04:27:47 PM »
My LED kitchen lights did not seem to be the right frequency to generate electricity on my solar cells but sunlight (even cloud covered) seems to charge it.
I'll paste a full 24 hr cycle tomorrow. Update - overnight and morning recharge in westerly side of the house to only indirect sunlight until afternoon.
«
Last Edit: December 17, 2017, 09:36:26 AM by HeneryH
»
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HeneryH
Full Member
Posts: 229
Re: WeatherShield + supercapacitor + tiny solar cell
«
Reply #4 on:
December 19, 2017, 08:25:32 PM »
That draw down graph above is totally not representative of normal ops. Maybe because it was the first charge and I didn't get a full charge on it.
Actual results are more promising than I hoped. :-) After a full day of charge (cloudy winter day) the moteino charged to 4.91v but then drew down the supercap so slowly that I thought something was wrong with the data recording function. The voltage just wouldn't come off of the full 4.91v.
I actually had to put the units in the dark basement for nearly a full day to force the supercap to start to discharge. I forget what time I put it into the dark room but it was about a full day and it only dropped to 4.57v. Now that I know what to expect I can get more scientific data.
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Kilo95
Sr. Member
Posts: 340
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Re: WeatherShield + supercapacitor + tiny solar cell
«
Reply #5 on:
December 19, 2017, 08:40:54 PM »
My weather station has been outside for the last 3 weeks and has never recorded a voltage below 5.01v. It stays there all the time. Super low power consumption
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HeneryH
Full Member
Posts: 229
Re: WeatherShield + supercapacitor + tiny solar cell
«
Reply #6 on:
December 19, 2017, 09:08:41 PM »
So one take-away here is... don't even bother thinking about doubling up on 7.5F SuperCaps. In fact, opposite, it would be interesting to see how low you could go before even noticing a change.
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Kilo95
Sr. Member
Posts: 340
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Re: WeatherShield + supercapacitor + tiny solar cell
«
Reply #7 on:
December 19, 2017, 10:02:12 PM »
It would be interesting. It’s gotten down to -9 deg Fahrenheit here once last week. Otherwise teens to 20s Fahrenheit. It’d have killed alkalines I feel pretty sure. Very impressed with Felix’s supercap/solar panel idea
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Felix
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Re: WeatherShield + supercapacitor + tiny solar cell
«
Reply #8 on:
December 20, 2017, 10:40:34 AM »
Quote from: Kilo95 on December 19, 2017, 10:02:12 PM
It’d have killed alkalines I feel pretty sure.
Actually I've used alkalines in the freezing cold and they worked fine. Maybe depends on their quality too.
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Kilo95
Sr. Member
Posts: 340
Country:
Re: WeatherShield + supercapacitor + tiny solar cell
«
Reply #9 on:
December 20, 2017, 10:51:50 AM »
could be maybe i had a bad batch. the supercap/solar panel definitely works well.
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WeatherShield + supercapacitor + tiny solar cell