What's a good power bank for use with IoT?
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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
@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.
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@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
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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
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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
@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.
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@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.
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@NeverDie I am happy to report that my batteries arrived yesterday!
@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?
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@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. -
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?
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OK, I did my battery test. @NeverDie @Nca78 @mfalkvidd
You can find it hereThe 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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OK, I did my battery test. @NeverDie @Nca78 @mfalkvidd
You can find it hereThe 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
@OldSurferDude Thanks a very valued to know. I was wondering today why my (big) powerbanks fall down after short time. I have small 1 & 2-pieces powerbanks, they work very well. I use also BSM hw-168 or hw-107 for charging single 18650. Will try to use them outside also with small solarpanels.
