Powering mote 24/7 using only a supercap and solar
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@Ed1500 said in Powering mote 24/7 using only a supercap and solar:
@NeverDie ah yes it does, but the RFM is usually connected to a microcontroller :-) So that is limited choice
i wonder if 1.8 Volt would seriously affect the range of the RFM69 (running mine from 3.3)Interestingly enough, the lower voltage doesn't seem to affect the range.
ATmega328p's can run at 1.8v also. In theory it should be set to run at 4mhz, but neither I nor anyone I know of has had problems running at 8Mhz down to 1.8v. If you run with BOD off and internal 8Mhz resonator, it only consumes about 150na while sleeping. That's why I haven't bothered going to ATtiny's. Maybe there are other reasons to do so though?
@NeverDie I have used Attiny's mainly for their size. Pricewise, compared to a pro mini clone it is a bit foolish, unless you use the smd versions.
I had an attiny+ 433Mhz transmitter built in one of those garden lamps with a moisture sensor at the base where it sticks in the soil. Worked well, Not ideal, but it was nice to play around with -
I recently purchased one of these:
https://www.aliexpress.com/item/Mega328-Transistor-Tester-Diode-Triode-Capacitance-ESR-Meter-MOS-PNP-NPN-M328/32685741297.html?spm=2114.01010208.3.92.KtC8xSand, for the price, it seems to do a decent job of measuring capacitance and ESR.
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@Ed1500 I got the bigger brother of that one. Look at the workshop discussion. I can't wait to start testing this stuff with all the voltage regulators I got and see how much energy I can actually store in the same 2 caps both in series and parallel
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@Ed1500 I got the bigger brother of that one. Look at the workshop discussion. I can't wait to start testing this stuff with all the voltage regulators I got and see how much energy I can actually store in the same 2 caps both in series and parallel
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@Ed1500 I got the bigger brother of that one. Look at the workshop discussion. I can't wait to start testing this stuff with all the voltage regulators I got and see how much energy I can actually store in the same 2 caps both in series and parallel
@gohan said in Powering mote 24/7 using only a supercap and solar:
Look at the workshop discussion.
Uh, what workshop discussion would that be?
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@gohan said in Powering mote 24/7 using only a supercap and solar:
Well, after much digging, I think I finally found your post. Is this what you're referring to?
Is it better than the one I posted?
I'm thinking of possibly getting one of these:
http://www.ebay.com/itm/261114892135
if only because the company that makes it also makes a popular low budget signal generator.I don't know that I actually need it though, except to verify that stuff purchased from Aliexpress actually is what it purports to be. :grinning:
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If anyone interested for some ideas of supercaps protection https://youtu.be/NsTAyD2i3rc
@gohan said in Powering mote 24/7 using only a supercap and solar:
If anyone interested for some ideas of supercaps protection https://youtu.be/NsTAyD2i3rc
Useful video if connecting capacitors in series. If using just one capacitor, though, I wonder whether there's any advantage to using the described shunt regulator circuit compared to simply using a 2.7v LDO voltage regulator?
By the way, if your supercap's will be in a higher than room temperature environment, you may have to de-rate their max voltage. In general, supercaps won't last as long at high temperatures. Worth checking the datasheet for the details if that's a possible concern.
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@gohan said in Powering mote 24/7 using only a supercap and solar:
If anyone interested for some ideas of supercaps protection https://youtu.be/NsTAyD2i3rc
Useful video if connecting capacitors in series. If using just one capacitor, though, I wonder whether there's any advantage to using the described shunt regulator circuit compared to simply using a 2.7v LDO voltage regulator?
By the way, if your supercap's will be in a higher than room temperature environment, you may have to de-rate their max voltage. In general, supercaps won't last as long at high temperatures. Worth checking the datasheet for the details if that's a possible concern.
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I think the Swiss guy presents an interesting notion, and it's worth watching for that. However, I think his part choice of the TL431 is a poor fit for my solar application. According to the datasheet (cf page 6 of http://www.ti.com/lit/ds/symlink/tl431a.pdf), the minimum cathod current required for regulation is between 0.4ma and 1ma. From indoors, that's generally more current than I'm receiving from the solar panel! Now, double that, because you'll need two of them.
Also, it can't handle very high currents either, which is, I presume, why the Swiss guy resorts to the transistorized circuit and/or the chinese supercap protector PCB circuit.
HOWEVER, I notice that TI has a more recent successor to the TL431, called the ATL431, which appears to address both of those shortcomings: http://www.ti.com/lit/ds/symlink/atl431.pdf
Also, the ATL431 price would be much less than the Chinese transistor supercap protector board. The ATL431 price is about 58 cents, quantity 1 (http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=229180358&uq=636316574771858018)
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I think the Swiss guy presents an interesting notion, and it's worth watching for that. However, I think his part choice of the TL431 is a poor fit for my solar application. According to the datasheet (cf page 6 of http://www.ti.com/lit/ds/symlink/tl431a.pdf), the minimum cathod current required for regulation is between 0.4ma and 1ma. From indoors, that's generally more current than I'm receiving from the solar panel! Now, double that, because you'll need two of them.
Also, it can't handle very high currents either, which is, I presume, why the Swiss guy resorts to the transistorized circuit and/or the chinese supercap protector PCB circuit.
HOWEVER, I notice that TI has a more recent successor to the TL431, called the ATL431, which appears to address both of those shortcomings: http://www.ti.com/lit/ds/symlink/atl431.pdf
Also, the ATL431 price would be much less than the Chinese transistor supercap protector board. The ATL431 price is about 58 cents, quantity 1 (http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=229180358&uq=636316574771858018)
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Has anyone seen this solution for balancing the supercaps?
https://www.youtube.com/watch?v=rWN7YOuhcO0 -
@gohan said in Powering mote 24/7 using only a supercap and solar:
Has anyone figured out how to do use this chip?
I haven't pursued it, because I haven't heard a strong argument as to why two or more supercaps are better than one for powering a mote. The economics of supercaps seems to favor a one supercap solution.
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Well it is all related to what voltage you need to store I'd say: if you need to use more than the standard 2.7v you need more caps in series (for example if you want to make a 12v pack for your car)
@gohan
Well, if you need more than 400F... maybe then. I'm sure there's a crossover point somwhere if the storage requirements get high enough. At that point, though, it would seem you're doing much more than powering a sensor mote.Anyhow, I look forward to seeing what you come up with. Maybe you've found an interesting use-case that I haven't even considered.
