68-Cent Powerbank
erco
Posts: 20,254
While shopping for switched glueable styrene battery boxes (unglueable polyethylene ones are everywhere) for one 18650 Li-Ion cells, I found these cute little yellow Powerbanks for 68 cents. Only the yellow# ones are 68 cents. Every other color costs more. Does yellow not sell?
Not sure if they are styrene or glueable, but I ordered several. They are a battery box plus a 5V boost circuit to a USB socket. Ordinary people will use it to charge their gizmos. But you and I see them for what they really are. Robot Chassis. I had to verify that the plural of chassis is still chassis.
http://www.ebay.com/itm/121864067222
And yes, my finder's fee for the twins' college fund is still a dollar, even if the item is under a dollar.
Not sure if they are styrene or glueable, but I ordered several. They are a battery box plus a 5V boost circuit to a USB socket. Ordinary people will use it to charge their gizmos. But you and I see them for what they really are. Robot Chassis. I had to verify that the plural of chassis is still chassis.
http://www.ebay.com/itm/121864067222
And yes, my finder's fee for the twins' college fund is still a dollar, even if the item is under a dollar.
Comments
I have to admit that I do not even have a project on-deck to use such a thing ... nor would I have time to start one in the next six months ... yet it is STILL tempting. Heck, at the very least, it is a more convenient 18650 charger than my plug-in one.
Ugh ... I haven't pulled the trigger yet, but it is in my watch list. Please advise the payment terms for the Twins fund, as I am slowly convincing my self that this needs to be in my tool closet.
I got the fever, brother, and the only prescription is more parts (I may never use)!
So it can charge itself. How bitchin' is that? Over Unity for under a buck.
Still only in my watchlist, though. I need to sleep on it before deciding how many to buy.
I haven't tried that one, but I've used a different brand of cyanoacrylate+primer on polyethylene, and it bonded well. The joint didn't look fabulous, but it worked OK.
When I was in the paint business, we sold some UV curable paint to a cellphone manufacturer. They were finishing some kind of plastic (sorry, don't remember exactly what kind), but the paint wouldn't stick without the plastic being flame treated. They provided us with a box of empty cell phone casings and the guys in QC would test the adhesion of of every batch of paint we made by making a quick pass or two across a casing with a propane torch, then applying the paint.
Dunno. The booster circuit alone is 68 cents: http://www.ebay.com/itm/0-9V-5V-to-5V-DC-DC-Booster-Module-USB-Mobile-Step-up-Power-Supply-Module-TE-/121285596454
This one has the battery box plus charge circuitry. More costs less!
Go Red Fire Monkey! http://www.chinesefortunecalendar.com/2016/
I bought a pair of the single battery cases and batteries to go with them to power my grandsons propeller clock many months ago, and I have a dual battery case.
erco, I just tried supaglue on my box. I will post the results here shortly.
PostEdit
Superglue works. Not sure what the box is made from. It does not look like ABS.
Cells are in parallel so it should work with one or two cells.
While we're ordering, add some bling to charg-ing with these light up power cables: http://www.ebay.com/itm/GLOW-led-light-data-sync-charger-charge-power-cable-for-iphone-6-4s-5-micro-usb-/361114310039
Just last night I ordered a toy induction heater and a 500W class D audio amplifier. The former is just for making nails glow - a variation on the propane torch. The latter is to drive large tape-wound toroidal transformers that then drive cascade generators...made from Chinese capacitors and diodes of course. May we all survive CNY.
They are sending out signals or something, because I just did almost the same thing ... except I bought (2x) Power Banks, a syringe of solder paste, (110x) dispensing needles, (10x) SMT crystals, (10x) micro-SD sockets, (10x) SMT EEPROMs.
Grand Total = $13.13 ... how lucky is that?!
The listings that are in Canadian Dollars are automatically on sale (1.41CAD to 1.00USD exchange rate, the last I looked). If a seller does not update as currencies change, then prices get wonky.
I stopped just short of finding a reason to buy this arcade-style 8-way joystick for $5.58. It is in my watch list for some future night.
EDIT: My sincere and humble apologies. I received another signal ... arcade joystick at $4.41.
I saw an article a few years ago which claimed that assembled USB flash drives with cases, connectors, and the controller chip which is itself a complete CPU with (sometimes hackable) firmware, wholesale at about the same price as the bulk flash chips; the controller, case, and etc. are essentially free.
Add free shipping, open source and cheap Chinese manufacturing into the mix, then ask the question: how can anyone afford to NOT be in this hobby?
Seriously, name another hobby that's getting cheaper and easier. I'm lumping programming & electronics & robotics & computers & drones together here. These ARE the good old days, guys. Once Uncle Sam figures out how to to charge us PER delivery, download, flight, app, post, and email, it's all over.
But for now, it's hammer time, the wild west of electronic entrepreneurial capitalism. Go for it, chase your dream, make your millions now. This opportunity might not last too long.
I have five or six cheap Chinese breakout boards on my desk right now -- H-bridge drivers, strain gage transducer interfaces, even a whole oscilloscope I bought as a kit. It's like electronic Lego. And it really isn't worth building yourself when you can get five assembled H-bridges, with proper crowbar control and LED indicators on board, for ten bucks shipped. I am doing stuff with bipolar stepper motors that I've had for over 15 years because before it was so much of a PITA to build a driver.
I really can't figure out why this stuff is subsidized so heavily; it's not like it's a big enough market to make a dent in anything tradewise. But it's a remarkable boon for us as hobbyists.
Hell, the ESP8266 boards would be a tremendous bargain even if the ESP8266 didn't do WIFI. And the damn thing does WIFI. I put some systems together a few years ago that included consumer wifi access points direct-cabled to ENC82J60 Ethernet chips to connect forklifts to a control center. Today that would be so much easier it's almost scary.
Erco has it right, and he is our prophet of the cheap chinese junkbox god.
Don't plan on using these with "protected" 18650's. They won't fit !
The regular 18650 is an extremley tight fit.
Since I only have (and use) "protected" 18650's, I will be forced to buy regular 18650's if I want to use these.
Plus you will need a very thin blade (like an Xacto ) to pry the lid off.
Also, make sure you have the correct Mini USB, I have several that are a different shape and won't fit.. (the cell phone USB does fit however.)
I expected that non-protected would be required, and only took a chance on these due to having a half dozen such cells from an abandoned laptop battery rebuild. Is it too much to hope that the output circuit has any sort of low-voltage cutoff?
I used one of the two-battery banks, with one unprotected battery installed.
I would guess the others are the same - - some of the other sellers state they have protection built in.
Most of the sellers do not mention that a Blue LED (steady on) is used to indicate power out
I tried charging without a battery installed, a Red LED flashed (probably to indicate no battery)
I used my digital storage scope for the test. The battery voltage "dips" ~ 1 volt, at 920.7 KHZ
Output is steady at ~ 5 V using a 200 Ma load.
When the battery "dip" reaches ~2.45V, (battery at ~3.6V), the Blue Led flashes.
When the battery reaches ~3V peak, "dip" at ~2.2v, the Blue Led turns off - Battery shuts down.
Voltage "dip" seems to determine when to shut the battery off
Good news is that they include a "protection" circuit ( at least on this model)
Hope that helps
Ken
Of course I had to take it apart first. FYI - there is no marking on the SOIC, so no luck looking up a datasheet. Then I put it back together and squeezed a Trustfire TR18650 in there (measured 3.82V). It is quite snug and would require some effort to dislodge.
Next up, trying to power something. I plugged the included cable into my wife's phone (not testing a 68 cent pack on my phone!). A blue light came on (as Ozark reported) and her phone began to charge.
Now, I am charging it from my work laptop docking station (again, not testing with my laptop!). A red light flashes at approximately 1 Hz ... no change over the past 5 minutes or so. I will give it an hour, then measure the termination voltage.
Attached are a few photos ... including the bottom of the PCB, so maybe you can fight the urge to pull yours apart.
Final voltage = 4.14V
Not bad. I may go back for more, to give homes to the rest of my unprotected 18650 cells.
It seems that some are better than others.
Also, someone pointed out that you could snip part of the spring to use protected cells. Seems obvious after reading it.
Discharge
Battery = 4.2V to 3.2V ... Blue LED ON
Battery = 3.2V to 3.0V ... Blue LED flash
Battery < 3.0 ... Blue LED OFF and load cutoff
Charge
CC/CV/trickle ... Red LED flash ... starts at 0.7A
Terminated ... Red LED ON ... terminates around 50mA to 70mA
Below are "features" that are translated from a site selling the devices:
Linear charge synchronous boost discharge, the built-in charging, power MOS chip set 0.7A synchronous boost charging current the maximum output current: 1A
Original output thermal regulation
Original creation Adaptive adaptor technology, guarantee the safety adapter
Constant current/constant voltage trickle/charge, and realize the maximum charging rate without the risk of overheating the thermo-regulating functions
C/10 charge termination, automatic recharge
4.2V preset charging voltage, accuracy up to ± 1%
Discharge output overcurrent, short circuit, over voltage, over temperature protection
2 LED battery indicator, charge and discharge instructions and indicates that
I feel better knowing the guts that make up these things. The exchange rate has skyrocketed them up to 71 cents, though. The listing showed 71 cents, but my total for 4pcs was $2.73 ($0.6825 each).
i]22FEB - Second batch arrived with MP3401A markings still on the IC[/i
I could *just* get a protected battery installed by taking the spring completely out, but that ain't going to work.
Opps! Just voided the warranty.