# DIY 18650 protection?



## MMACH 5 (Jan 28, 2010)

Has anyone here added protection to harvested 18650 cells?

I ran across this at DX:
http://www.dealextreme.com/details.dx/sku.26112

I would not have known what I was looking at, if it wasn't for the two threads showing disassembled protected cells.

I've got several unprotected 18650 cells sitting around but I rarely use them. If I could add protection, I'd be more likely to use them.

I suppose I'd use heat shrink over the battery after applying, right?


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## haji (May 20, 2010)

I am planning on trying this. I will let you know how it goes. It's not big priority though, so may take a few weeks.


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## VWFringe (May 26, 2011)

The Protection Circuit from All Battery





has pads for B+, B-, P+, P-

They're instructions are:


> Connection Port illumination
> 
> 1. B+: Connec to cell's anode
> 
> ...



but I'm still not clear on how to connect it
for a single 18650 do both P+ and B+ have a wire going to the anode, and same for the other two pads?

and can someone help on choice for wire...i'd like to use a pair from cat-5 

Thanks,

ps: interesting I can't find any specific directions for this anywhere on the Internet, guess this is that serious...?

pps: I accept responsibility for my actions


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## VWFringe (May 26, 2011)

*18650 Shrink Tubing= 32mm*

FYI
All Battery shrink tubing for 18650 please choose 32mm, not 19mm. (their sizes are not diameter)


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## Microa (May 27, 2011)

Please find the typical wiring diagram for a single li-ion battery.


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## VWFringe (May 30, 2011)

I apologize for not knowing how to read this diagram. I do have good solder technique. Can anyone help a layman understand how to use these boards? Specifically where each pad needs to go to or whether all four need to be used in a single cell configuration?

Thanks in advance,

Unenlightened


ps: I asked the supplier and they said it depends on how I want to configure it. (then I spent several hours on on the internet...nada)


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## Microa (May 30, 2011)

The solder pad P+ and B+ on the board were wired together. P+ is an optional solder pad for the battery pack which doesn't use the positive battery pin as contact point.


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## VWFringe (May 31, 2011)

thank you very much, i see the trace under the resist now

can i get away with using a pair from some cat-5? or even just one wire - it's not really carrying the load just isolating the negative if tripped?


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## Microa (Jun 1, 2011)

In theory, the thicker the wire is better because thin wire increase the resistance of the circuit. I would like to remind you not to use Cat-5 cable because the insolator of the Cat-5 cable is made of PE which can not withstand temperature above 70 degree C. When you solder the wire to the battery, the insolator will melt. Flat metal stripe is excellent for this job.


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## VWFringe (Jun 3, 2011)

I've been searching for flat wire, but don't know the right search terms I guess, can anybody point me in the right direction? I can't find any online and don't have a shop locally. (I think I found similar on alibaba, but no use for that much wire)

these are the most expensive free batteries in the whole world i think, given the time i've spent


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## MikeAusC (Jun 4, 2011)

There are two risks in adding Protection PCBs to LiIon cells

1. Soldering to the cells will risk an explosion or permanent damage to capacity at best. You can only use cells which have solder tabs. 

2. A wire from the positive button needs to run down to the Protection PCB - you must be absolutely certain that this wire cannot short out to the case - you will have a fire !


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## VWFringe (Jun 5, 2011)

MikeAusC said:


> There are two risks in adding Protection PCBs to LiIon cells





VWFringe said:


> pps: I accept responsibility for my actions


 
i have a hakko 456-16 60watt soldering iron, suitable for fast soldering on Li-Ion cells

where can i find the wire?

i think it's a given this should not be done by someone who is not fully aware of the methods and dangers involved, but leaving the cells unprotected for e-cigarette use would be worse.

I hope this just isn't done much and isn't a secret, hahaha


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## Lion251 (Jun 6, 2011)

You ask: "Where can I find the wire?". But the item at DX that you link to in the first post of this thread has the metal strips already connected, ready for welding (or soldering).


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## Fallingwater (Jun 6, 2011)

MikeAusC said:


> There are two risks in adding Protection PCBs to LiIon cells
> 
> 1. Soldering to the cells will risk an explosion or permanent damage to capacity at best. You can only use cells which have solder tabs.


I beg to differ. I wrote a guide just for this.

I don't *guarantee* you won't set fire to stuff by doing that (as clearly stated in the disclaimer), but as far as I'm concerned, LiIons are quite solderable if you know what you're doing.

That said, for a while now I've only considered buying flashlights that have protection circuits built in the driver, and if I had one without I'd solder the protection circuitry *to the driver*, not to the cell, because using protected 18650s has size complications, and protected cells are more expensive.


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## LEDAdd1ct (Jun 6, 2011)

Fallingwater said:


> [...]and if I had one without I'd solder the protection circuitry *to the driver*, not to the cell, because using protected 18650s has size complications, and protected cells are more expensive.


 
An excellent idea! Now you have protection for any unprotected cell you use in the light, and can buy cheaper, unprotected cells, from known good manufacturers, but still avoid many of the risks.


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## VWFringe (Jun 6, 2011)

so i guess the wire's not available, 

i very much appreciate the idea to protect the e-cig instead of the battery - it actually solves the problem of having to fabricate a battery terminal, lol, hahahaha

and accomplishes the main thing they need, since the charger they're getting does cc/cv well (thanks to the reviews on this site!), which is prevent them from vaping it down to an unchargeable state!


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## Microa (Jun 6, 2011)

There are 3 functions for the protection circuit.
1) Overcharge protection 2) Over discharge protection 3) Short circuit protection.
If the protection built in to the driver, overcharge and short circuit protections are dismantled. In order to minimize the risks, you would put the battery back to the torch immediately after recharge. So, a charging connection should also be built in.


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## Microa (Jun 7, 2011)

Regarding the flat matel wire, do you think the desoldering braid can help? It is copper, flexible, solderable, and flat but not so thin.


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## VWFringe (Jun 10, 2011)

someone on ECF suggested contacting my local Batteries Plus store, as salvaging the flat wire maybe possible from dead cells
i'll report back if that's any luck

as to braid, cool idea, 

need to buy kapton tape also, lol, free batteries, lol

EDIT:


> There are 3 functions for the protection circuit.


 I did understand that wiring it in wouldn't be the same


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## Microa (Jun 10, 2011)

Hi VWFringe,

Did you read this thread? http://www.lygte-info.dk/info/battery%20protection%20UK.html
It's worth to have a look.


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## Bauer (Aug 8, 2013)

*Adding protection pcb to 18650, what wire to use?*

I have a couple of the 4A protection pcb's from fasttech but they didnt come with any wires or button top. I am wanting to add these to a couple samsung 2400's.

I have kapton tape and wanted to see if copper tape (like the kind you wrap on p60's) would be good enough? Its pretty thin so i could use more than 1 layer if I need to.

Another thing is the button top for the positive contact. Any homemade options or will the tab be ok?


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## bshanahan14rulz (Aug 9, 2013)

*Re: Adding protection pcb to 18650, what wire to use?*

copper tape might be thin enough, but make sure to use your kapton, and not rely on the adhesive layer of the copper tape to insulate it. 

Button tops are only for applications that cannot work with flat tops. A blob of solder on the driver's contact pad ought to fix that issue.


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## naazrael (Aug 10, 2013)

VWFringe said:


> I apologize for not knowing how to read this diagram. I do have good solder technique. Can anyone help a layman understand how to use these boards? Specifically where each pad needs to go to or whether all four need to be used in a single cell configuration?
> 
> Thanks in advance,
> 
> ...


http://www.trillion-sz.com/datasheets/Protection_IC/1CELL/CS213DS_Rev1_2_20100315.pdf

That should explain the box in the schematic (note, not diagram).
It shows the pinout of the chip. Now the resistor (marked R1) is likely just for current limiting purposes to protect the chip. The FETs at the bottom control the logic for either charging or discharging. The V- pin is to provide a reference to see whats happening at Vss, like to see if its overdischarging or something.


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## degarb (Nov 24, 2013)

Bookmarking this thread; I spent last 20 minutes looking for instructions for adding the protection circuit to an 18650. 

http://www.rchacker.com/announcements/trustfirebatteryexplosion
The above link explains to me why so many "protected" cells are exploding: they aren't protected at all. Furthermore, I own 6 of these, thinking they are protected. 

Rather than throwing away my six Trustfires, I am thinking of adding the dx.com (or open to alternative suggestion) protection circuits to the cells. 

I am also assuming no harm in accidentally double protecting cells.



Interesting find of an magnetic 18650 fuse:
https://www.youtube.com/watch?v=hbXug5XoG0Q#t=90 I don't see where to buy. (Though it wouldn't give over and under voltage protection.)


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## degarb (Nov 24, 2013)

http://www.gotvapes.com/index.php?main_page=product_info&products_id=1091

http://thevapesafe.com ... I tad high priced for redundant protection. Ahh, some smoker will buy it.

Seems 18650s can cause lung cancer when used improperly. I never knew. I also never knew how high tech smoking is becoming. Are the kids getting bored with meth chemistry?

Some of the vendors claim it (thevapesafe fuse) has low voltage protection, which seems like bunk to me. Neither can I see it preventing over charging. Just at 7 amps, it blows.


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