Powering mote 24/7 using only a supercap and solar

[gohan]

Maybe a small booster to 3.3v could be used, since power efficiency shouldn't be a huge deal since the you will have the panel charging most of the time

[NeverDie]

@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]

So, I just ordered this:
https://www.aliexpress.com/item/3PCS-fala-capacitor-2-7v10f-super-capacitor-high-current-Low-ESR-fast-delivery-2-7V10F-ultra/32715563451.html?spm=2114.13010608.0.0.qFbHqn
and this:
https://www.aliexpress.com/item/CNIKESIN-2PCS-Fala-Capacitor-2-7v10F-Super-Capacitor-High-Current-Low-ESR-Fast-Delivery-2-7V10F/32804681189.html?spm=2114.13010608.0.0.qFbHqn

from the same seller that gohan used. It's a risk, but if either of them check out, I may buy more of that brand.

I'll make a posting after I receive them to say whether they seem to be good or not. :)

[NeverDie]

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.KtC8xS

and, for the price, it seems to do a decent job of measuring capacitance and ESR.

[Ed1500]

@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

[Ed1500]

@NeverDie interesting. May get one too

[gohan]

@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

[Ed1500]

@gohan keep us updated :-)

[NeverDie]

@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?

[gohan]

https://forum.mysensors.org/topic/229/your-workshop

[NeverDie]

@gohan said in Powering mote 24/7 using only a supercap and solar:

https://forum.mysensors.org/topic/229/your-workshop

Well, after much digging, I think I finally found your post. Is this what you're referring to?

https://www.banggood.com/DANIU-3_5inch-Colorful-Display-Multi-functional-TFT-Backlight-Transistor-Tester-p-1083042.html?p=9825091683131201505R

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:

[gohan]

Actually I went for the 2017 version on aliexpress that also has a pulse generator

[gohan]

If anyone interested for some ideas of supercaps protection https://youtu.be/NsTAyD2i3rc

[NeverDie]

@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.

[gohan]

I'll experiment when I'll get the small adjustable dc-dc converters and see how they go.

[Ed1500]

@NeverDie The unforgettable "guy with the swiss accent" videos :-)
Though very useful information, not so applicable to me as I am using 5,5V capacitors on a regulated 3V3 line

[NeverDie]

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)

[Ed1500]

@NeverDie Oh that is good to know, thanks

[gohan]

Has anyone seen this solution for balancing the supercaps?
https://www.youtube.com/watch?v=rWN7YOuhcO0

[NeverDie]

@gohan
Sounds better than the Andreas Speiss method. Thanks for posting it!