What's a good power bank for use with IoT?


  • Hero Member

    For use in conveniently testing low power IoT devices, I've tried a number of factory made power banks, and the result is always the same: they turn themselves off because the IoT devices is drawing too little current! Which power banks don't do that? In searching, I've so far only come across one rather pricey power bank which says it won't do that:
    https://www.amazon.com/gp/product/B07PKSBS7J/ref=ox_sc_saved_title_1?smid=A1F3RS3IOEG1Z2&psc=1

    Are there any others? Yes, I can build a stand-alone power power source, but I'd prefer if a power bank I might already own could also be used. Short of that, I've ordered the following less expensive things to try, though they aren't power banks in the conventional sense that you might typically bring along with you as a portable power reserve for your phone:

    https://www.amazon.com/gp/product/B0784FPF8J/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

    https://www.amazon.com/gp/product/B07SZKNST4/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1

    https://www.amazon.com/gp/product/B01M7Z9Z1N/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1


  • Banned

    What do you want to ask?😯


  • Hardware Contributor

    @NeverDie said in What's a good power bank for use with IoT?:

    https://www.amazon.com/gp/product/B07SZKNST4/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1

    I've 2 very similar (not sure if exactly the same) to the single battery one and they work fine.
    I can confirm they don't stop unless you switch them off.


  • Hero Member

    @Nca78 Thanks! So far, so good. I'm powering an Ikea white LED wreath that consumes just 30ma at 2.6v for the entire wreath. It's surprisingly bright considering the low power drain of the LED's.
    alt text
    My wife was annoyed with the Ikea power pack that came with it, because it would only light for 6 hours at a time before turning off. So, she asked me to "fix" it. Well, I did, and now it won't go off until the 18650's from the new power pack are drained, which will take quite a while.

    I'm using some 18650 cells that I previously acquired from a solar cell vendor on ebay at a reasonable price. Where does one even find a good source anymore for high quality 18650's? There are just so many fakes out there these days.


  • Hardware Contributor

    @NeverDie said in What's a good power bank for use with IoT?:

    I'm using some 18650 cells that I previously acquired from a solar cell vendor on ebay at a reasonable price. Where does one even find a good source anymore for high quality 18650's? There are just so many fakes out there these days.

    For me, old laptops, Dyson battery packs etc.
    Else good quality Chinese brands, as I'm in Vietnam and the probability to have genuine products from other brands is close to 0 🙂


  • Mod

    @Nca78 do you have any tricks to separate the good chinese brands from the bad ones?


  • Hero Member

    I was wondering the same thing, and also: do the counterfeits counterfeit the quality Chinese brands? I'm guessing so, in which case, mfalkvidd and I, not living in Asia, may not fare any better with them either.

    Unrelated: considering the high cost of new lithium ion cells these days, the TalentCell (above) may be a reasonable price to pay, because it appears to come with some decent cells. Running the wreath off it now to get an idea as t how long TalentCell will power the wreath...

    This is where I previously bought some 18650's: https://fullbattery.com/collections/batteries-1/products/ncr18650ga-protected. They're good quality-- I verified their nominal capacity with a constant current load test--but the price has nearly doubled since then. I get the impression this may be true across the board, not just with this particular vendor.


  • Hardware Contributor

    @mfalkvidd I mostly bought LiitoKala and Soshine from a reliable local supplier. I also bought a few Vapcells 18350, as they have an ID code that you can check online http://antifake.vapcelltech.com/anti-fake.html

    Those brands have good or very good reviews on lygte-info website, except the overly optimistic high current capacity, but I don't need them for that. Lygte info is the best place to check a specific brand and model.

    On the opposite side of the quality spectrum, I wouldn't buy any of the TrustFire, UltraFire, GTL, GTF, etc that you see a lot on AliExpress and similar websites. They usually have only a fraction of the stated capacity, they are often re-wrapped 2nd hand batteries, can have fake control circuits etc.


  • Hardware Contributor

    @NeverDie said in What's a good power bank for use with IoT?:

    I was wondering the same thing, and also: do the counterfeits counterfeit the quality Chinese brands? I'm guessing so, in which case, mfalkvidd and I, not living in Asia, may not fare any better with them either.

    Yes they do, they even counterfeit the websites as you can see on the vapcell link I posted above...
    So no it doesn't sound like a really better option in US/Europe.



  • @NeverDie

    I have the same situation, power banks shut off. I have chosen to go the route of a 18650 battery, TP4056 battery charger and a carrier. My application is a remote soil moisture monitor. I charge the battery with a solar panel My power down state draws less than 1mA (my meter doesn't go any lower)

    I really appreciate the discussion on batteries. I got sucked into buying some that barely had only 700mAh. Yes, the price has gone up a lot, but still better than constantly buying one use 9V batteries. I ordered two batteries from Newegg ($9.50ea-shipped) and just ordered some from fullbattery.com ($11.25ea-shippd) I'll be running a capacity test on them.

    Thanks for posting


  • Hero Member

    @OldSurferDude If you're into solar, check out the Sunpower C60 solar cells that fullbattery sells as well. That's actually what led me to find fullbattery.com in the first place. It's an interesting value proposition because you can dogbone them together yourself. Still, that leaves you on your own to seal them up behind glass if you want a permanent installation, and that's where it all gets a bit tricky if you want it to last long-term and not have the sealing epoxy brown out and get all crispy from sun damage. This is the predominant reason why I haven't yet installed any significant solar on my home: I'm not sure which vendor is trustworthy to deliver a solar panel that will truly last 20 to 30 years without going bad from uv degradation or moisture intrusion or corrosion or whatever. If you have a solution to that one, I'm all ears.

    Also, now that there has been breakthrough development on perovskite solar cells, it's further reason to delay. If/when that scales up and becomes mainstream at low cost, it's going to be a huge improvement overall, in both energy harvesting as well as bang for the buck. But, of course, if you need something today, you can't really wait around for that.

    Lastly, if you're in the market for not just one or two lithium ion 18650 cells, but 10 or more of them, you might find that dismantling Milwaukee power tool battery packs will be more cost effective, especially if you can catch them on sale during a Black Friday or post-Christmas sale or something. Milwaukee uses quality cells in their packs. I have a number of Milwaukee lithium ion battery packs that I purchased in 2010 and which still are able to hold 70-80% of their original charge capacity, which I think speaks well for them. Since I'm not a bluecollar worker who uses cordless tools all day long, that means they're effectively as good as new as far as I'm concerned: I never get anywhere close to fully discharing them. Lastly, it's worth knowing that time is on your side: when Milwaukee ships new battery packs they can only sit on the shelf for so long before accumulated self-discharge threatens to undervolt them. Naturally, Milwaukee would rather sell them at a large discount than have them go bad on the shelves and become a total loss. It's at that point that Milwaukee is forced to cut prices and blow them out in a sale event, as retailers are not equiped to recharge them.



  • @NeverDie I like your suggestion for solar panels, though my application only requires 1x 5W panel. And I like the idea of dismantling the power packs.

    I think we differ in our approaches, though. I seem to enjoy living on the "bleeding edge", that is, I'm more of a risk taker. My first house solar system, 2.8kW, was installed in 2004. When I upgraded to 4.2kW, I took the 14 panels and installed them on my hillside, so now I'm a net energy exporter. The 2.8kW portion is still producing at 85% of nameplate, shows little environmental degradation (sealant, too), and has paid for itself. The reward outweighed the risk.

    In taking risks, I learn much. Yes, I have a quite a few scars, actually and metaphorically. I have discovered a philosophy: Everything is an experiment. The point of an experiment is to learn something. So every experiment is a successful, just that sometimes the desired results are not realized. Eg. leaving an Arduino outdoors results in a short useful life. Spraying on a sealant extends the outdoor life.

    Good discussion. Thanks for the ideas

    OSD



  • I just ordered some batteries from fullbattery.com. I got an email that my order had been shipped. Upon further investigation, I found that only the tracking number had been pulled, but the item had not been received by the shipper from the fullbattery.com.

    I've seen this before from vendors that are less reputable. Money is collected and then the vendor orders the part from another source. So the vendor gets the float on the money plus the mark-up. Sometimes, the order remains in this state for months and ultimately, the vendor cancels the order without informing you. When you contact the vendor, only then it is reported that the order had been canceled. Finally, you have to submit a request for refund, which eventually comes.

    For me, the jury's still out on fullbattery.com. I'm posting this to see if anyone else has had this experience


  • Hero Member

    @OldSurferDude He was slow to ship in my case as well. I sent him some emails to ask why, and it seemed as though he wasn't aware that the order had been placed. Shortly afterward he shipped it. It may be that he doesn't get many orders and so doesn't check his email for orders often enough. So, maybe it's standard for him. I can't know for sure, but I don't think anything nefarious is going on. Do let us know if you never get your batteries though.



  • @NeverDie I am happy to report that my batteries arrived yesterday!


  • Hero Member

    @OldSurferDude said in What's a good power bank for use with IoT?:

    @NeverDie I am happy to report that my batteries arrived yesterday!

    Have you done a capacity test on them? Do they still measure up to what they're spec'd at?



  • @NeverDie
    I'm going to dissipate the energy through a 25 ohm resistor. It will take about 24 hours to perform one capacity test. Often times I read that the full capacity won't be available until after a few charge-discharge cycles. 2 resistors, 4 batteries, 3 tests each. Assuming that I stay on top of it, it will take at least a week of testing which won't start until I get my 25 ohm resistors. I'll post a link to my full write up.


  • Hero Member

    I've often wondered at what rate 18650 cells are discharged to arrive at their capacity ratings? It's well known that discharging at a slower rate will yield a larger apparent capacity. Of course, a quality battery would show the actual curves in its datasheet.... but in cases where there's just a single number given, and no context, I wonder how it's done?



  • OK, I did my battery test. @NeverDie @Nca78 @mfalkvidd
    You can find it here

    The batteries from Newegg and Fullbattery are good ones.

    If you going to buy a large quantity and looking for a low price, then you should buy 1 or two and test them as I have done here. You might have to "kiss a lot of toads" before you find a good vendor, though.

    OSD


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