Photos of Protected Lithium Batteries

LuxLuthor

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I made a post in Sosa's thread about the exploded battery in his Fenix light (nothing wrong with the Fenix), and got 3 PM's from people recommending I make this thread showing the images so people understand what a "Protected" & "Unprotected" Lithium battery looks like. If the moderators feel this is cross posting, please close the topic.

I'm a relative newbie. Can you explain the difference between protected and unprotected cells? I have RCR123As with the name Powerizer on them. Doesn't say where they were MFG-ed. But they do have a plastic "wrap" on them and what appears to be two vent holes on the positive end. Are these protected cells?

It's a very good and important question. When we say "Protected" we mean a separate computer chip that is added and gives a cutoff (breaks the circuit in the battery from completing) if the voltage goes too low, the voltage goes too high, the current amperate goes too high, and the cell temperature rises too high.

I sacrificed a Year Old (Current improved model has new features) of AW's 14670 cell to show you exactly what this means.

Click on the thumbnail images below. AW starts with a normal UNprotected cell in blue plastic which he also sells. These have the vent holes which help release pressure if the temperature rises, and gas expands. That means the starting blue, unprotected cell just has high temp venting protection (as far as I know).

Now note there is a thin computer chip on the bottom under a metal disc. One end is welded to the bottom (Negative Terminal) of the blue battery, and the other end uses a thin contact strip to run along the side and attach on the top Positive terminal.

It is this computer chip that does all the important sensing and interruption of the circuit, otherwise the blue cell is an unprotected cell. The additional black shrink wrap and label are added to keep the components anchored and insulated. You can feel and see the space at the bottom of the bottom of a protected AW battery where the PTC circuit is locate4d.

Please note AW's improvements on current version which parallel those of Pila in his post #9 of this thread. Excellent News because I have had a number of my Li-Ion's drop to the floor.


If the ones you are buying for other lights, such as R123 do not specify that they have this kind of protection, and especially if you don't see the circuit gap and feel the thin strip along the side, then it's pretty safe to assume you are not using protected Lithium cells. I hope this illustrates more clearly what a "Protected" battery actually means.






Finally, if I remove the blue wrapper you see the metal canister with the plastic circle on top that separates the Negative entire outside and the inner, middle top positive end. It is a shiny, stainless steel casing, it just photographed a darker color.

 
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LuxLuthor

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As my images show. There is a difference between a "PTC" "Positive Temperature Coefficient" vent holes (that elgarac mentioned above), and this electronic voltage/amperage circuit protection which is put on a computer chip. Many hear PTC as "Protection Circuit" which it is not.

Very few if any Li-Ion cells will have a circuit added like AW does. One other very high quality Lithium cell brand that does is Pila which is more expensive. However, in addition to many other demanding specifications, notice that Pila uses a white plastic ring to give better shock/impact damage to the chip and components use a layer of thick tape under metal end plate to insulate the chip from a fall. Stop and think about what happens if a battery falls on the bottom end in terms of crushing/damaging the chip components, which is yet one more thing to be careful with. (Most, if not more of these same features have now been added by AW's improved, current and more affordable priced brand, which is great news)


Click on Thumbnails

 
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Raoul_Duke

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Nice pics lux, and thanks for doing this. ( Althought I have already pulled apart li-ions, and knew this, I never thought it would have been a good Idea to post pictures to educate others.

In addition to dropping the cells on the circuits, squeesing to many cells into a small flashlight body risks damaging the protection cuircuit. Also a strong / stiff tailcap spring has been known to wreck the protection curcuit on Protected cells.

Now that you have bare cells, have you any plans to damage them further, to demonstrate the hazard involved in peircing the cells etc?

( That was said tounge in cheek BTW)

Please dont hammer a nail through them, but I have picked up from your post you own guns, so prehaps shooting them from a safe distance would be fun with a video cammera recording the results :D
 

AW

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Lux,

The picture you shown is the earliest version of my cells ( more than 1 year ago ). My new cells have a different construction now.

AW
 

carbine15

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Lux,

The picture you shown is the earliest version of my cells ( more than 1 year ago ). My new cells have a different construction now.

AW

I have two questions:

1. Why does the circuitry always go on the bottom of the cell. It seems to me that there is no need to create another negative path when one exists that is the under wrapper. If you could make the circuit integral with the button top of the cell, you could eliminate an entire layer of insulation and eliminate the need for the contact thread (wire running from top to bottom) that so often makes protected cells not fit in some applications.

2. Wouldn't it be cheaper and more effective against drops if the entire circuit was potted with non-conductive epoxy?

Maybe the reason this isn't done is because of the vent holes that need to be there just in case the cell gets angry. I'm sure there's a way to preserve the holes and mount the circuit on the top thus saving valuable width.
 

AW

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carbine15,

I think you have already answered your own question. There is no way to built an integral protection circuit with the vent assembly without blocking the vents or eliminate the ground path. The extra thickness of a protected cell comes from the bump of the wrapper. However, the industrial grade shrink wrap is still the toughest and provide the best protection against abrasion and wear compared to consumer wrappings.

AW
 

LuxLuthor

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Lux,

The picture you shown is the earliest version of my cells ( more than 1 year ago ). My new cells have a different construction now.

AW

Yeah, I know you made a change...but I didn't want to sacrifice a new cell! LOL! I stopped using these old 14670's and I used another to verify my contact welder worked properly with it.

What is the improvement....better protection of the PCB chip? I mainly just wanted to show the concept of how it is made, where the separate pcb is located, and what makes it different from unprotected.

I highly recommend AW's cells.
 

AW

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Since then I have upgraded the protection IC and insulation material. The new insulation material is cut to surround and support the pcb from being crushed ( same thickness with pcb components ). It has a high flash point ( 300 degree C ) and won't deform/melt like plastic above 80 degree C. The insulation for the nickel connecting strip has been replaced with heat resistant tape ( 260 degree C ).
 

LuxLuthor

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AW, that is really great news. I edited my above posts to reflect these improvements. I only did this to illustrate what a protection circuit looks like, so I'm sorry I didn't sacrifice a new model for all the shots....but I'm using those !!!
 

Fallingwater

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Thanks for the pics. I'll be removing the step-down converter from a 3v RCR2 cell shortly, and I already had an idea of how to do it, but your pics confirmed it.
 

LuxLuthor

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I just happened to have one of the newer improved AW 14670 Li-Ion cells that I decided to sacrifice because I kept wondering just what secrets it had over the older AW version.

Here is one more "contribution to the cause" so no one else is left wondering about the nice enhancements AW made. It shows his willingness to listen and improve the quality of his batteries, in addition to his lower pricing and excellent service. :thumbsup:

The red spacer is about 1.15mm. The contact strip is insulated from body with 1mil (0.001 inch) Kapton tape.

Click on thumbnails for high res.




 
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PhotonAddict

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Lux, thanks for sacrificing yet another one for the "cause".
btw: Is the last photo a picture of board with the protection circuit? ie., the negative contact of the battery?
 

LuxLuthor

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Lux, thanks for sacrificing yet another one for the "cause".
btw: Is the last photo a picture of board with the protection circuit? ie., the negative contact of the battery?

Yes. There is an outside metal disc covering the back of the PCB (Printed Circuit Board) at the NEG terminal end of the battery. Don't know what that glue is that attaches it...maybe Arctic Silver Epoxy?
 

RGB_LED

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LuxLuthor, thanks for sacrificing your batteries for the cause and for providing this information. I have used AW's 750mAh and LiFePO4 RCR123's, 17670's and 18650's for about a year now and, while I have had no complaints, I had been contemplating getting other brands of batteries but this is just further confirmation that there is no need as AW's are the best out there.

This is comforting information as there have been several threads in the past year about exploding CR123's - primaries and from other manufacturers. Thanks AW, for actively improving your batteries to make them better and safer for us all. :thumbsup:

I think I'll be putting in a new order soon for more AW batteries... :santa:
 

radellaf

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So on the RCR front, is it correct that there are like four different kinds the same size?
1. Straight unprotected 3.7 RCR123
2. Protected version
3. Regulated to 3.0V version (i assume ckt also protects)
4. LiFePO4 3.2V

Is #4 a replacement functionally for #3? Where the chemistry makes it need neither voltage reduction or protection circuitry?

I hope so, as I want to use two, safely, in a 2xCR123 Inova 3W LED (T3 i think).
 

LuxLuthor

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Last I checked on the topic, those were the RCR 123's I was aware of. There are pro's and con's to the #4, including safety & reduced capacity that makes it not be an identical performance trade.
 

LuxLuthor

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Had a number asking me about the length of AW's C Li-Ion with protection circuit as compared to the Kai unprotected model. I measure AW's length 53.5mm including button, or 51.5mm to top adjacent to button.
 
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