# How can I tell if an 18650 is protected?



## larryf (Jun 13, 2011)

Is there a way to tell if an 18650 actually has the protection circuit installed? Most of my cells from KD and DX that claim to be protected have an indentation near the positive side of the battery. Some do not, and sizes vary between manufacturers. I purchased five on Ebay and one is much larger than the rest, all are supposedly the same type. 

Removing the label would be a sure way to tell but will possibly damage the battery and not be productive (yep, it was protected but i can't use it now :duh2: )

I plan on purchasing some very high current flashlights in the near future, just want to be safe.

Larry


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## HKJ (Jun 13, 2011)

Look at the bottom of the cell. This picture series will probably help you.


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## RepProdigious (Jun 13, 2011)

Short em, if they dont explode on you they were not protected...

Nah, seriously. Most of the times you can see the positive strip running down the side of the cell on protected ones (because the protection is 99% of the time on the (-) or bottom side of the cell). The indentation near the top isnt really significant. Also, when the bottom looks like the copper on a circuit board its usually protected, if the bottom is metal ist either unprotected or is has a extra steel plate (like AWs cells)


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## nfetterly (Jun 13, 2011)

AW has current draw limitations noted on his 18650 protected cells (black wrap like in the photo above - GREAT link!) - the older 2200 mah, 2600 and now 2900. The 2900 are the highest rated in this series.

However - the IMR (red wrapped cells from AW) will handle high loads very well - and due to the chemistry do not require a protection circuit. If you are highly concerned these are a good alternative.


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## larryf (Jun 13, 2011)

Thanks.... That really is a good link, explains things well. Closer inspection of my protected 18650s shows the 'strip' on the side. Not sure why I thought the indentation on the top contained the circuit, but I can see where it is now.

Larry


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## jasonck08 (Jun 14, 2011)

larryf said:


> Thanks.... That really is a good link, explains things well. Closer inspection of my protected 18650s shows the 'strip' on the side. Not sure why I thought the indentation on the top contained the circuit, but I can see where it is now.
> 
> Larry



Although it is much more rare, I've seen some protected cells that have the PCB on the top. The one advantage to that is you don't have to run a nickle strip down the side of the cell.


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## HKJ (Jun 14, 2011)

jasonck08 said:


> Although it is much more rare, I've seen some protected cells that have the PCB on the top. The one advantage to that is you don't have to run a nickle strip down the side of the cell.


 
I wonder about the length of these cells? There might also be a problem with the vent holes.


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## RepProdigious (Jun 14, 2011)

jasonck08 said:


> Although it is much more rare, I've seen some protected cells that have the PCB on the top. The one advantage to that is you don't have to run a nickle strip down the side of the cell.


 


HKJ said:


> I wonder about the length of these cells? There might also be a problem with the vent holes.


 
I wonder about this also, i've heard rumours of their existence (but mostly from people who simply have no idea what they're talking about and are just plain wrong) so i'd love to see some pictures on an actual specimen!


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## jasonck08 (Jun 14, 2011)

I have a RCR123 sample with the PCB mounted on top.

It's one of these. Here is a Link to an image I found in google of the cell.

They are a bit funky and the top of the battery is wider than the rest of the cell. About 17mm near the top. Got a couple of them about 2 years ago for testing.


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## RepProdigious (Jun 14, 2011)

jasonck08 said:


> I have a RCR123 sample with the PCB mounted on top.
> 
> It's one of these. Here is a Link to an image I found in google of the cell.
> 
> They are a bit funky and the top of the battery is wider than the rest of the cell. About 17mm near the top. Got a couple of them about 2 years ago for testing.


 
Wow, those are horrible....


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## Napalm (Jun 14, 2011)

RepProdigious said:


> Short em, if they dont explode on you they were not protected...



With so many e-bay fakes around, that's actually the only true way to know.....


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## RepProdigious (Jun 14, 2011)

Napalm said:


> With so many e-bay fakes around, that's actually the only true way to know.....


 
Hey, looks like i made a little type-o.... i wrote it the wrong way around


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## RepProdigious (Jun 14, 2011)

cpf s fckd up again......


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## xjasperstudentx (Dec 25, 2012)

*How Can you tell if a battery is protected?*

i'm buying rcr123 and 18650's battery and not sure if they are protected i'm getting it from goinggear.com. The battery is EagleTac Protected 18650 3100 mAh Rechargeable 3.7V Li-Ion Battery  and EagleTac Protected RCR123A 16340 750mah Li-Ion Rechargeable Battery i know it says protected but ive seen on youtube some batteries are not protected! Thanks!


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## Thr3Evo (Dec 25, 2012)

*Re: How Can you tell if a battery is protected?*

a few good rule of thumb points:
1. GoingGear is a well trusted source
2. By the pcb at one end of the cell and the strip that runs along side it under the wrap. 
3. The cell will always be a bit longer than its name(original size). Example: 18650 protected will be longer than 65mm ranging from that all the way to 70(ish)mm.


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