I was looking for batteries online yesterday and found a Chinese Wholesaler that will ship for FREE so as I was looking through the thousands of types to choose from I started to get confused. Some batteries would clearly state they had PCB Boards which means they are safe to stack right? Then some of them would just say that they had overcharging and undercharging protection and then some just said they were protected and of course some didn't say anything about being protected. Are all of these protections the same thing or are there different types of protection on different batteries?
PCB Protection Questions
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The protection circuit in li ion batteries does three things #1 under volt protection it shut the battery off once it get to around 2.75 volts. If li ions get too low a voltage it will damage them. #2 over volt protection this makes sure the battery doesnt over charge and get damaged or explode. #3 is over discharge protection. This shuts the battery off if too many amps are being drawn off the battery. which can also cause damage and /or a explosion
Might want to watch out for china batteries a lot of knock offs and poor quality cells coming out of there. I wont use anything but Japan or Korean made li ion or IMR batteries. Saving a few bucks on batteries is not worth having a PV blow up in your face. i highly recommend using ONLY! High Quality li ion cells in mods.
Might want to watch out for china batteries a lot of knock offs and poor quality cells coming out of there. I wont use anything but Japan or Korean made li ion or IMR batteries. Saving a few bucks on batteries is not worth having a PV blow up in your face. i highly recommend using ONLY! High Quality li ion cells in mods.
I agree with Java. I'm no battery expert, at least not quite yet, but I have been doing a lot of reading recently, and it seems to me that stacking batts is one of the things that raises the risk level the most, if that is what you are set on doing, I would follow Java's advice and get high quality cells, lots of those super cheap ones are counterfeit from what I hear...
Stacking protected cells is no more hazardous than a single cell. The protection works regardless of how the cells are connected
When people say "stacked cells", they are often referring to the 3.2V LiFePO4 cells. Those can provide a suitable voltage when stacked where voltage is too high when stacking 3.7V cells.
LiFePO4 cells are typically not protected and are typically not rated for the currents required to power an atomizer. Those are the ones that have failed catastrophically when stacked. They are a "safer" chemistry, but that does not eliminate the possibility of thermal runaway.
The safest configuration is either a single protected cell or stacked protected cells which requires a regulator.
When people say "stacked cells", they are often referring to the 3.2V LiFePO4 cells. Those can provide a suitable voltage when stacked where voltage is too high when stacking 3.7V cells.
LiFePO4 cells are typically not protected and are typically not rated for the currents required to power an atomizer. Those are the ones that have failed catastrophically when stacked. They are a "safer" chemistry, but that does not eliminate the possibility of thermal runaway.
The safest configuration is either a single protected cell or stacked protected cells which requires a regulator.
Interesting point o view 
. After now I think, stacked it`s refer to any batt`s. However what for stacked 3.2V when we have VV with 3.7V stacked .
. After now I think, stacked it`s refer to any batt`s. However what for stacked 3.2V when we have VV with 3.7V stacked .The batteries I am stacking are two CR2-123 Ultra-Fire 3.0 volt batteries. Are these LiFeP04 batteries you are talking about?
Stacked 3.2V cells are sometimes used in unregulated mods that accept an 18650 or 17670 cell. Open circuit voltage is around 7V (they come off the charger at 3.6V), but since the cells have higher internal resistance than ICR or IMR types, voltage at the atomizer under load is around 5.5V which can work well with a 3Ω atomizer.
The problem with the CR2 (RCR123a) LiFePO4 batts is they may be over-loaded when powering an atomizer. They are typically not high C rate cells. A 2C cell with 500mAh capacity has a max drain of 1A. A 3Ω atomizer draws almost 2A with two of them stacked.
I'm not sure on the chemistry for any particular make/model CR2 batt. Some are LiFePO4 and some are not. Typically, 3.7V CR2 cells are the protected ICR type and 3.2V CR2 cells are the unprotected LiFePO4 type. Whatever the case, making sure the cells are protected will eliminate any concerns. Otherwise, if using unprotected LiFePO4 batts, the user must take care the drain limit is not exceeded.
My feeling is that it's best to avoid LiFePO4 batts altogether and use a couple protected ICR batts with a regulator. They're sucky cells anyway. The energy density is considerably lower than any other Li-Ion battery and with the higher internal resistance, they are considerably less efficient.
The problem with the CR2 (RCR123a) LiFePO4 batts is they may be over-loaded when powering an atomizer. They are typically not high C rate cells. A 2C cell with 500mAh capacity has a max drain of 1A. A 3Ω atomizer draws almost 2A with two of them stacked.
I'm not sure on the chemistry for any particular make/model CR2 batt. Some are LiFePO4 and some are not. Typically, 3.7V CR2 cells are the protected ICR type and 3.2V CR2 cells are the unprotected LiFePO4 type. Whatever the case, making sure the cells are protected will eliminate any concerns. Otherwise, if using unprotected LiFePO4 batts, the user must take care the drain limit is not exceeded.
My feeling is that it's best to avoid LiFePO4 batts altogether and use a couple protected ICR batts with a regulator. They're sucky cells anyway. The energy density is considerably lower than any other Li-Ion battery and with the higher internal resistance, they are considerably less efficient.
@CraigHB
So the batteries I have are the ones you were talking about. I remember the sign said LiFeP04 and I told the guy behind the counter that I heard negative things about those types of batteries and he just shrugged it off. I also asked him if they were protected and he said something to the effect of "it isn't going to matter." I was specifically asking him to tell me what would be safe to stack to make a high voltage mod. Can you figure out whether the battery is protected or not just by its physical appearance? For example because of the positive end has the vents etc?
So the batteries I have are the ones you were talking about. I remember the sign said LiFeP04 and I told the guy behind the counter that I heard negative things about those types of batteries and he just shrugged it off. I also asked him if they were protected and he said something to the effect of "it isn't going to matter." I was specifically asking him to tell me what would be safe to stack to make a high voltage mod. Can you figure out whether the battery is protected or not just by its physical appearance? For example because of the positive end has the vents etc?
Well, you can't always trust someone behind a retail counter knows what they're talking about.
The 3.2V Li-Ions use the "safer" LiFePO4 chemistry, but the CR123a sized cells are not intended to be used for high drain applications. They're mainly a rechargeable replacement (designated as RCR123a) for things like cameras, smoke detectors, and other consumer electronics. For those applications, they are safe enough without protection, but for an e-cig, the load may be too heavy.
3.7V protected cells are commonly available in the CR123a size, but are sometimes referred to as 16340 which is not entirely correct. A 16340 is 16mm x 34mm and a CR123a is 17mm x 34.5mm. A CR2 is actually somewhat smaller than a 16340. There's some ambiguity there. You need to verify the particular cell dimensions for your application.
There's also this cell. It's actually a 3.7V ICR cell with a built-in 3V regulator. If that is the cell you are using, it should be okay since it's protected and has a relatively high drain limit. Because it's an ICR cell with a built-in regulator, two in series will deliver 6V under load, unlike stacked LiFe cells which sag below that under load. The down side is they require a special charger that can only be used for those particular cells.
If it's not indicated on the label, there's no easy way to tell for sure if a cell has protection. Sometimes you can tell there's a protection PCB on the negative end under the shrink wrap. Typically, the 3.7V cells are protected and the 3.2V cells are not.
I appreciate trying to help me figure this stuff out but now I am even more confused unfortunately. I was under the impression the PCB protection was on the positive side of the battery because of the vents, cap, and piece of cardboard or plastic covering the top which helps from shorting out from bumping the positive side with a metal or aluminum whatever your using. If that is supposed to be on the negative end then every battery I have every used has not been protected. I uploaded pics that shows what I am talking about. The top part of the battery is the positive end which looks exactly like what your picture shows on the negative end. Very confused...
The vents, cap, and piece of cardboard is not what is referred to as "protected".
A "Protected cell" has a circuit board with overcharge/over discharge/over current/short circuit protection.
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I don't use the RCR123A 3.6/3.0 cells. So rely on others more familiar with them.
Rocket
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To me that looks exactly what is on the positive end on the battery in my picture. The battery in my picture and what I was asking about is not an RCR 123a battery it is a Tenergy 3.7 volt 1400 mAh Li-ion battery. Here are the specs. Its the one highlighted in the red box.
View attachment 86267View attachment 86268
Here are the exact RCR 123 a batteries I have that I uploaded the picture and the extremely limited details about them from the actual website of the shop I bought them. Because the specs were basically non existent and know knew exactly what model number the batteries were I searched the internet and found some additional information on them but everything is still unclear because of contradictions within the specs from on its own page on the website. I uploaded the pics and added comment to them below.
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You're right, it's hard to find any manufacturer data on them. I found them for sale here with a Google search. That retailer says they are protected. It looks like they are similar to the Tenergy cells I linked to earlier. They may have a built-in 3V regulator. In that case, the circuitry may in fact be on the positive end. In any case, it looks like they are protected.
BTW, those cells are 15mm x 27mm (15270) so they are CR2 size exactly.
BTW, those cells are 15mm x 27mm (15270) so they are CR2 size exactly.
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