Protected cells or MODS for those dirt cheap 18650 power banks?

EDC Gear for Flashlight Carriers USB Power Devices
1

We all know those cheap, single 18650 power banks that sell for under 2 bucks delivered from China.

All the ones I’ve bought (LCD or plain), stupidly can’t fit protected cells. I’ve searched BLF/laser forum/etc and the only ones that do, are not of the “dirt cheap” variety.

First: are there any known dirt cheap ones that DO take Protected? (Like the $1-2 1-cell variety, preferably.)

Alternately, please show or discuss your mods! Simplest/easiest (“stupid simple”) preferred!
^I don’t mean removing protection circuits from 18650s, as for me, the idea is for cheap (but safe) gifting. Those little power banks also supposedly charge 18650s, though I want a failsafe. There’s no application where I’d more want a protection circuit, than someone charging and using an 18650 from one of those ‘power banks!’

BTW, those little $1-2 power banks aren’t so bad. I just measured one giving a straight 1 amp, at over 4.90 volts.
I don’t know how well they do when the cell sags, but on a fresh cell, I was actually impressed for the price.

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Hi!

Mmm, as far as I know, powerbanks' circuitry include the battery protection chips already so, no point in fitting a protected cell inside (unless you have no other at hand, that is). Stripping off the protection PCBs from the batteries should be more or less easy, in most cases it's just a PCB wrapped over the battery cathode, with a thin metal strip which goes up to the anode you can leave in place.


Cheers ^:)

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I too believe the circuitry in those cheapy things is supposed to have overcharge and over discharge protection. But supposed to have and having high enough quality parts to be dependable are two questions I’d rather not answer by having an event as experienced by folks who bought those hoverboards that went up in flames.

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Hi, Bakuti!
You know, you’re right. I actually put a 2 amp load on one identical to pictured above, and it did shut down… some kind of protection circuit is already in there. Do I trust it entirely? No, not really. Moreover, do I trust neophytes with unprotected cells (such as putting them in a pocket, purse, or luggage with keys, change, or other metal objects)? No!

My idea was:
My policy is, when I give a flashlight to a non-flashaholic, the battery is always protected. I don’t trust the users, nor the cheap chargers I give them (which I’ve sometimes seen charge cells too high, or never terminate). What’s worse is, I use such cheap chargers myself, and noticed they can work fine for a few years, then go bad. I just don’t want to be the cause of something bad happening, such as a fire, or even the cell being killed by a charger. Usually, they don’t use their flashlights, and would probably find these cheap little power banks quite handy, maybe even more handy than the light.

What I’d like to do is, for them to be able to use the one Protected cell I gave them, for both devices. I know it seems like I’m a cheap bastard, but all these ‘cheap’ pieces (charger, flashlight, protected cell) add up for multiple people.

If the protected 18650 would fit in the Power Bank, it would prevent me from buying an extra unprotected cell just for use for the power bank. Also, some applications need button top, and protected cells are always button top. Plus, neophytes understand the polarity of button-tops better.

I just bought a bunch of protected, button-top NCR18650B’s from Gearbest (amazing deals on ncr18650b’s, by the way). I am looking into circumcising some of the protected cells (I’m against genital cutting, but not against battery cutting), and I also realized that the NCR (nickel cobalt) should actually be a safer chemistry, so maybe protection isn’t 100% necessary, I’d just prefer to have it there for gifting, most especially to prevent short circuits. Most people should not be handling 18650 cells as if they were AA alkalines, but the protection circuit, quality cell, safer chemistry (and some education) can all help.

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I tested some cheap DIY USB power banks a while back. The protection circuitry worked. If anything, it worked a little too well, cutting charging and discharging a little early at 4.1v and 3.23v.

I don’t think they had room for protected cells either.

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Yes those are exactly the devices I’m talking about.
Nice review, I’ll try to read the full thing when I have more time.

This is the first ‘cheapo power bank mod’ I’ve seen, thanks. I have read multiple people claim that they modded their cheapie 18650 power banks to take protected cells, even saying “easy mod”, yet no details or photos. I’d really like to see such mods, for ideas. Your idea of adding an extra wire to the battery lead dovetails with my idea to somehow lengthen the lead and box. I thought about cutting up the existing plastic body, to maybe lengthen it somehow. Ideas???

I also (less seriously) considered getting a 1 x 18650 battery holder, and somehow take out the Power Bank guts and wire to the battery holder. I think you can actually just get the “guts part” of those power banks by themselves, but I don’t have a lot of time for modding. Most people would probably also not feel comfortable using something that looked like that, and I either wouldn’t get around to it, or wouldn’t feel comfortable letting someone use it unsupervised, kluged, often exposed electronics either. I think lengthening the existing box is best, but I’m sure someone else could come up with a better way than I can come up with (and honestly, I’m drawing a blank). I’m thinking about buying a number of these, to have for emergencies and/or to give away, keep in different locations, etc. So I’ll go for the cheapies.

BTW extra info:
The non-LCD variety tested at 4.92 volts at .98 amps.
The LCD variety tested the same amps, but only 4.88 volts.
Both these were with a fresh 30Q at 4.20 volts, both with a dummy 1 amp draw.
I recommend people getting a 1A/2A dummy load usb device on Ebay, they’re only a couple bucks, and a great complement to a USB multimeter. Mine draws very pricely 1/2 exact amps. I just ordered a variable one which goes up to 3A, but it looks like there are no markings on the control, so you probably need a meter (and a good power supply) to know what the load is actually set to. Personally, I’d like to see where the overcurrent protection of these things kicks in, as I know the cheapo power bank can provide a full amp, at least on a fresh cell.

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Use an Lii-100 as a bank instead? :smiley:

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brjones, here's how I implemented a compact, effective battery holder:

(Open the image in another window for full resolution)

So, this is my simple recipe to attach leads to the batteries:

  1. Neodymium magnets; ∅8×1'5mm disc shaped ones above.
  2. Hot glue.

Where did you measured those output voltages? They seem weak…

Cheers ^:)

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EC Tech has the 22,xxx mah battery and some YTer opened his 2nd oen it’s 8 18650s with circuitry. A xiamii and similar spec 10,400 or 10AH is a 4 18650. Other slimmer ones are using 5000 or 2500 mah cellphone batteries,

I’m thought of makign them, but ATM for 31-40 bucks EC Tech have the cheapiest bang for your buck. I’ve tried buying empty shells and they do sell the ec tech 8x18650 shells for 3-10 dollars on ebay. Wrecking a 12 cell laptop battery the lowest is 20 bucks on ebay. so for all it worth or you could make your own circuitry over-charge/low/battery inidcator etc… but it’s barely worth it.

links: http://www.ebay.com/itm/EC-Technology-Portable-Charger-22400mAh-External-Battery-Power-Bank-High-Capa-/302033218936?hash=item4652952d78:g:uCEAAOSwCfdXpFle
http://www.ebay.com/itm/USB-LED-Mobile-Power-Bank-Charger-Pack-8pcs-18650-Li-ion-Battery-Case-Holder-/252239299276?var=&hash=item3abaa242cc:m:muB4JSPrse4b6ukCTKVe4cg
http://www.ebay.com/itm/12-Cell-8800mAh-Laptop-Battery-For-HP-Pavilion-DV4-DV5-462889-121-484170-001/151468672619?\_trksid=p2045573.c100505.m3226&\_trkparms=aid%3D555014%26algo%3DPL.DEFAULT%26ao%3D1%26asc%3D38530%26meid%3Dcc06274101a64e95ac71d6e7588984c7%26pid%3D100505%26rk%3D1%26rkt%3D1%26

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@Barkuti:
Wowsers.
Is there a pic of the finished product? What were the other ingredients? I see two 26650’s, wire, and the guts of some kind of device.

The voltages were measured by a USB power volt/current meter. Here is one example with more than just voltage and current/amps.

Anyone who does USB charging (and who doesn’t?) should have (at least) 1.

Also highly recommended: a USB dummy load generator. The cheap ones like below will produce an exact 1A or 2A load, depending on the switch position. It dumps the electricity as heat with the resistors. More-expensive ones are adjustable.
You can run this in serial with the USB voltage/current tester. Because you rarely can be sure how much current other devices are really trying to pull.

I promise, you’ll be surprised what you see you ‘spy’ on your USB power supplies when UNDER LOAD, be they wall warts, solar chargers, or battery banks. At rest, most power supplies are a little over 5V, usually 5.1V give or take, but under load, things often fall to pieces. It is also stunning to see the effect different USB cables, even short ones, have on voltage drop. Buyers can pick up the above gear for probably $3-5 USD total if they shop carefully.
So yeah—in my experience, staying at 4.92 volts delivering basically a full 1 amp load? That’s good for an extremely inexpensive USB device!

One thing I have not tested, is computer ports, as I ironically don’t ever use them for USB power.

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Here's a pic of it, brjones:

PCB link: SC-0176B 1A+2A DIY Dual USB Mobile Power Bank PCB Module @FT

Cheers ^:)

P.S.: I gave it as a present to a friend, who is now away on a trip. Gonna be upgraded with a pair of LiitoKala 26650-50As once he returns home. :-)

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wow really clean build. How much would you need to make these for sale? lol
I’ve been looking for uses for my 26650/26670 cuz most of my 26650 flashlights are given away or broken.

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Well, in this age of mass manufacturing I could probably only make a profit with such stuff if marketing it a$ fin€ pi€c€$ of craftman$hip art, LOL! :-)

I am currently building another one for a buddy who at least has somewhat funded it.

With the advent of the LiitoKala 26650-50As, power density and capacity/price ratios for 26650s have turned out waaay more interesting, indeed.

Cheers ^:)