Is my battery protected?
Not all batteries are protected and unprotected batteries will be damaged if discharged too much.
There is a couple of ways to see if a cell has protection:
Most protections are placed at the bottom of the cell as is fairly easy to see.
Due to the protection the bottom of the cell may also look different.
When the protection is place at the bottom of the cell it always needs a connection to the top.
The length always works for 18xxx cells, also if the protection is in the front part of the cell.
With 16340 cells the length may not work always as indicator of protection or not.
The front of a front protected cell looks slightly different.
Is a unprotected cell really unprotected?
When the protection circuit is missing, will the cell just exploded when mistreated?
The answer is, of course, no, but it can easily be damaged beyond repair. The build in protection is there to prevent fire and explosions, not to prevent damage to the cell.
A cell can have two protections inside the can:
One is a pressure valve that will usual disconnect the battery permanently when it vents. This is often called a CID (Current Interrupt Device).
When a cell vents it will be with a rather high pressure that may blow the front and back of a flashlight. This is not a fault, but the last safety measure to prevent that the cell explodes.
The second protection is a PTC, this is a temperature sensitive resistor. It will have a very low resistance at normal temperature, but at a certain temperature the resistance will increase dramatically and reduce the current flow.
A PTC will reset itself when it cools down, this may degrade the cells performance.
In some modern cells this function is supplemented or replaced by HRL (Heat Resistive Layer) that will disable the battery if it gets to hot.
The PTC may not be present in high current cells and it may also be missing in cheap cells.
Notes
How is a protected LiIon battery constructed
Disassembly of cheap 18650 battery
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
Great info, thanks for all your efforts here! H)
Thanks for the info mate!
Thanks for the effort HKJ. Very informative.
My current and or voltage measurements are only relevent to anything that I measure.
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Good Day HKJ,
Valuable info....
Thank You Very Much,
George
Thanks HKJ
I don’t remember seeing any cells with the protection at the positive end.
I wonder which cells have PTC or HRL.
Good to know that my pink unprotected Samsung ICR18650s have the vents.
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Thanks HKJ , Good post !
35amp 18650 battery: http://www.szsibeile.com/product_view.asp?id=147 & http://www.alibaba.com/product-detail/35amp-Genuine-cell-18650-IMR-35A_6... ——————————————————- company:ShenZhen sibeile Technology Co.,Ltd Efest Homepag
Highly appreciated!
Awesome HKJ…thanks!
will the CID or PTC be affected when the top of the cell gets dented in by the flashlight which happens on most flashlights over time
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I cant remember how many times people have asked how they can identify protected cells. Thanks for the great tutorial!
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That will depend on the exact construction, but probably not.
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
excellent, thanks
The Journal of Alternative Facts TM
"It is critical that there is a credible academic source for the growing and important discipline of alternative facts. This field of study will just keep winning, and we knew that all the best people would want to be on board. There is a real risk in the world today that people might be getting their information about science from actual scientists"
That is exactly the reason I decided to do this article, now anybody can give a good answer with just one link.
I tried to keep it simple, but I did get technical in the last part. I wanted to include some information about what unprotected cells was (I did have to open a few old cheap cells to find one with a PTC).
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
Thanks HKJ,Great.
www.enova18650.com
Excellent information here! Sticky’d. Thanks a lot for putting this together.
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Very useful . Thanks! :bigsmile:
Welcome to the Forum!
Great post wiyh many informations !! Many thanks !
Supply Samsung LG Sony Panasonic Sanyo IMR batteries, chargers, LED flashlight, smartwatch.
Brilliant info that newbies like me can keep coming back to as we forget
,cheers hkj
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Subscribing so I can point others to this info
Phil
Great info. Very informative. Was just wondering if my batteries were protected or not, and Robo referred me to the thread. Turns out my batteries are protected.
Thanx.
Just came from your site. I believe there are some double posts in last group of pics.
Oops, fixed, Thanks.
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
Fantastic little guide, HKJ. Thanks again!
Nice information to check battery protected or not. Thanks for sharing this useful information
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Thanks HKJ.
Will the added protection board cause difference in diameters?
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It will make battery longer but the diameter will be almost the same or just slightly larger (~0.5mm or so) because when you add protection you have to use one more layer of wrapping foil because there is an additional “flat” wire that goes from protection PCB to opposite pole and it needs to be isolated.
Usual yes, due to the strip fro plus down to the protection board at the minus end.
Some just add a new layer of wrap, other removes the old wrap or buy unwrapped batteries to start with.
The length of a 18650 cells can be up to about 72mm, but usual is below 70mm
Accepting 19mm diameter and from 65 to 72mm in length will handle as good as all sizes 18650. There is also the issue about flat vs. button top, the extra length due to that is included in the 70/72mm, but remember that on a flattop the isolation can be a few tenths mm above the plus pole.
My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/
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