Hello mogur and other ECF members,
I just recently joined this forum and have been browsing around quite a bit. Upon finding this thread, and realizing that it has been relatively active through it's life I figured there'd be no harm in joining in on the conversation. Just reading the first few posts were quite startling. There are obviously still some major misunderstandings of li-ion tech probably circulating on the forum. I am going to make a best effort to provide some clarity. I will do this in a quote/response method while going through the thread. Nobody should take any personal offense to being "corrected" as I am certain that everyone had the best intentions regardless.
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How safe are lithium ion cells?
The potential for injury and considerable property damage is definitely a concern. One of our members just experienced an explosive fire in his back seat from a lithium. There's videos of exploding lithium batteries all over You Tube, and seemingly endless recalls of laptop batteries. But, before you go throwing your ecig in the ocean (wouldn't help, anyway, lithium ignites in water),
Lithium-Ion cells do not actually contain any lithium-metal. It is true that once a li-ion OR lithium-primary cell goes into a thermal runaway condition, the likelihood of extinguishing the resulting fire with water is very low. It is a chemical fire. The intensity of the resulting fire or off-gassing and toxicity of the off-gases depends on the specific chemistry of the cell. Lithium Cobalt chemistry (most common) as well as Lithium-Manganese-DIOXIDE (primary cells, not to be confused with Lithium-Manganese-Oxide secondary (IMR) cells), both produce their own oxygen during a burn and can release dangerous levels of hydrofluoric-acid (highly toxic, attacks nervous system, relatively small doses can kill). In other-words, these cells "fuel" their own fire.
I advise a longer perspective. Despite the media frenzy, I have only heard of one injury. An early cell phone battery burned the face of a man. Commercial ecigs are relatively safe if used normally. They incorporate a micro chip that prevents both over-discharge rates and under-voltage conditions of the battery.
Good advice here. My only concern is do we really know for sure what chemistry they are using for those commercial ecigs? The little 8mm x 40mm jobs seem like a risky maneuver, we have to hope that they are not LiCo chemistry. I assume they aren't in *most* cases of good quality ecig, but I should point out, that LiCo chemistry AAAA cells are available. Most of this stuff is made in China and there is no liability from that far away. The cell could be anything. I have not personally seen any on-cell protection circuits small enough to mount to the end of a 8mm diameter cell, it was just recently that a small enough one became available for 10440 size cells. I don't know that it should be assumed that all "ordinary-commercial" egics contain a proper protection circuit.
[/quote]Their chargers (usually) prevent overcharging and subsequent thermal runaway. However, electronics can fail so the most frequent battery castastrophes occur while charging. DO NOT stick your charger on a window sill, on carpeting, or near any other flammable materials (especially curtains), just because it is near the most convenient outlet. Find a spot on a flame resistant counter (kitchen, bath) and don't leave the house or leave it charging overnight.[/quote]
This is also good advice, but I will add to it and say that it should be assumed that all cheap li-ion chargers charge incorrectly until proven otherwise. I developed the philosophy of guilty until proven innocent for li-ion chargers several years ago when I discovered that most of these new "consumer-oriented" loose cell li-ion chargers available on the Internet did not actually use a proper charge algorithm for li-ion chemistry, nor did they properly terminate the charge.
Also, don't charge until the green light comes on and then give it few more hours, like I have heard repeated so often.
This is EXCELLENT advice that should be followed by anyone using a li-ion charger that has not been tested and proven to properly terminate the charge. Ordinarily speaking, there would be nothing wrong with leaving the device plugged in, but you can not trust that these chargers are built correctly.
That is a myth leftover from the days of NiCds and NiMHs that have a 'memory effect'.
Actually, the whole "memory" effect as portrayed by the advertising departments for nickel chemistry cells was also a huge myth..... but that's not something we need to worry about for the sake of the topic at hand
Lithium ions have no such memory effect. None. Nada. They don't need to be 'topped off' like NiMHs, nor frequently discharge cycled like NiCds. They do like a moderate discharge to 3 volts or so every 100 charges to recalibrate the electronic surveillance circuit that monitors its charge status.
The only devices that contain any such "surveillance" circuit would be modern "smart" electronics like cell phones, laptops, mp3 players, etc. No need to worry about this on simpler devices like ecigs and flashlights.
What about modders?
Aaarrrgggh, matey, we're pirates, not girly-men. We only have one leg and one eye, anyway. But, if you happen to be a nerdy pirate, then it would be wise to always use 'protected' lithium ion cells.
First, all rechargeables in a can have a vent. When a cell overheats and the pressure starts to build, the vent opens and dissipates the excess pressure to avoid an explosive event. Unfortunately, the vent can fail. And, in the case of a Li-Ion cell, thermal runaway often overcomes the vent's ability anyway. Because of this particular concern in Li-Ions, a thermal fuse, or more commonly, a positive temperature coefficient (PTC) current limiting switch, is incorporated near the vent. This usually prevents the cell from reaching thermal runaway temperature (about 166C). Since LiPos aren't in a can, they do not explode, they simply have a flaming vent occurance, known in the trade as a 'Holy Crap... I don't want to be a pirate anymore' moment.
The term "protected" as it applies to li-ion cells is actually more of an either/or. It should never be assumed that a cell labeled as being "protected" contains a PTC. The term "protected" usually just means that the cell has a circuit mounted to the end of it that attempts to prevent over-discharge, over-charge, over-current, and short circuit. (often called a "PCB" or "protection circuit board")
But on with the 'protected cell' lecture. As a modder, you have the choice of a protected or unprotected cell. They sell both types at most suppliers. This is the final line of defense for us idiots.
The first line of defense would be the build quality and proper implementation of the cell to begin with, in the case of customs, the first line of defense is the human in charge of that cell selection and implementation. The second line of defense is a functioning protection circuit, the third and final line of defense is the PTC.
It is essential to choose the protected type in any single cell situation.
Actually, it is multi-cell applications that pose the highest risk when working with unprotected cells. In a series configuration, cells with variations in capacity can wind up reverse charging other cells in the circuit towards the end of the batteries discharge. Reverse charging a lithium primary or lithium secondary cell is extremely dangerous. The highest occurrence of CR123 primary "explosions" are caused by cells used in series configurations that were not matched for state-of-charge before use. More often than not, those CR123 primary cell explosions were not the fault of the consumer, but rather, caused by factory defect cells with below normal capacity that were assumed to be "like-new" by the consumer. When those lesser performing cells were mixed with properly performing cells, a reverse charge condition was created, leading to the potential for thermal runaway. Nearly every CR123 "explosion" that I am aware of occurred on cells that claimed to have a PTC device, in each case, the device failed to prevent catastrophe. Funny how CR123 primary (non-rechargeable) cells have a much worse track record than li-ion (if you take the RC LiPo crowd out of the comparison). I actually derive comfort using li-ion cells INSTEAD of CR123 primary cells in my flashlight collection. It's SAFER!
Single cell applications are actually an area where lacking a protection circuit can be managed with very reasonable safety by a properly educated modder who uses his brain and his DMM.
The protection circuit itself actually introduces it's own degree of safety issues. See... in order for a protection circuit to "monitor" cell voltage, there must be a conductive strip that runs the length of the cell to complete the circuit to the PCB. In the event of an unfortunate physical accident, it's possible for the thin insulator material between that strip and the cell can to be damaged, causing a short circuit right on the cell.
I would argue that the largest danger in using li-ion cells comes from improper implementation and cell quality. Modern name brand US, Japanese, and Korean made cells are in a whole new category of safety than first and second generation cells going back into the early 90s. An unprotected name brand cell from a reputable source made in the last couple few years is arguably safer than a protected crap-fire unknown brand Chinese import cell with a name that suggests that you should "trust" it or something of that nature... (TRUST that it will FIRE, lol). A li-ion cell can "go-off" without any warning, or can be aggravated to "go-off" through misuse. generally speaking, a culmination of factors must come into play for a li-ion cell to burst into flames. One of those factors, perhaps one of the most important, is the level of impurities introduced during the manufacture process. I wouldn't put it past a Chinese exporter to manufacture batteries in a dirt floor warehouse. Not saying that it IS happening, just saying I wouldn't be surprised.
This protection consists of a tiny pcb with a micro, a voltage sensor, and an electronic switch. It's frenched into the cell, just under the anode plate. Its job is to prevent thermal runaway and over-discharging of the cell. It monitors current drain on the battery and shuts the circuit down in runaway conditions.
I'm not aware of any protection circuit on a loose li-ion cell that contains thermal protection. Many global protection circuits that are wired to battery packs DO have the ability to monitor pack temps (like in laptops). In the case of the single protected cell, the hope is that the electrical protections in place will wind up preventing an exaggerated thermal condition from ever happening in the first place.
It also shuts the circuit down to avoid an undervoltage occurance.
Most PCBs have their low-voltage cut-off set at ~2.5V. Under a moderate to heavy load, this will generally result in the cell rebounding to a voltage in excess of 3.0V open circuit, which is considered reasonable for cell health. Even with the low-voltage protection in place, it is possible to mildly over-discharge a protected li-ion cell if the load is relatively light.
Most importantly, it prevents overcharging. These functions do not interfere with normal use, they simply add a mandatory insurance policy. (Okay, okay, maybe the overcharge mode can tangle with the charger's cutoff circuit and the charger light can toggle colors, but that isn't much of a penalty since you can just consider the change from red as the 'charged signal' and don't have to wait until it is fully green.)
Funny you mention that the over-voltage protection shouldn't interfere with ordinary use... The irony of this, is that most protection circuits put on loose li-ion cells over the last 5+ years have had their upper-limit set purposely a little on the high side in order to prevent the cell from terminating a charge prematurely in chargers that don't use a proper CC/CV charging algorithm. While on the one hand, they were trying to maximize compatibility, the other hand in the deal is that a different type of improperly built charger (of which I know exist) could wind up trickle charging a cell far beyond the 4.25V maximum recommended charge voltage.
Another interesting limitation of most protection circuits is that, due to the intended application of most of the loose protected li-ion cells available to consumer over the years (flashlights), the high current limit is generally set higher than the true safe maximum continuous rate. In many cases, it is set a LOT higher. The reason for this stems back to the early days of li-ion powered flashlights and li-ion conversions for flashlights. At the time, incandescent flashlights were still king. Incandescent bulbs are kind of like attys, power hungry heat machines. In the early days, people quickly found out that the lower resistance of a cold filament, and the short spike of current (in-rush current) caused by that cold filament, would trip the current-limit of the PCB. Even though the continuous operating state of the bulb was below the maximum safe rate for the cell, the PCB got in the way of being able to power up many bulbs. This lead to a demand for a work-around of the PCBs. To this day, it's not uncommon for the PCBs current limit to be set at 2-4X the maximum safe continuous discharge rate.
What about lithium polymer?
You had to get fancy, huh? Well, lithium polymer (Li-Poly, Li-Po) is a close brother to traditional lithium ion (Li-Ion, LiCoO2) and uses the same cobalt oxide type cathode. The difference between the two is the polymer electrolyte of the Li-Po. It does have the best output (largest mouth) with huge discharge rates of up to 30C. The term 'C' refers to the nominal charge rate of a battery. In reality, it is just the capacity of the battery (in mAh) expressed as amperage. Thus, a 500mAh battery charged (or discharged) at 1.5C simply means a charging rate of 750mA (1.5 x 500mA).
Technically speaking; "C" rate is primarily a function of time. Doesn't matter if it's charging or discharging. A "1C" rate means that the complete charge or the complete discharge occurs over the course of 1 hour. 0.5C means 2 hours, 2C means 30 minutes. During a discharge of say for example, a 1AH battery, a 1C discharge rate may actually only be 950mA because of the losses to resistance in the cell at the higher drain rate than the label capacity was derived from. In reality, most manufactures and resellers have moved away from this technicality and just treat "C-rate" as a multiple or divider of the label capacity of the cell.
Is that it?
No. Lithium Manganese (LiMg204, spinel) and lithium iron phosphate (LiFePO4, LFP) have recently been developed and hold some advantages over traditional lithium cobalt (mainly safety). But of course, then there are their disadvantages which mainly are that they aren't widely available yet, and they have different voltages and other characteristics which make them an extra hassle to use. But DX is starting to sell LiFePO4 cells in convenient sizes, so it may be time to experiment.
Obviously some time has passed since this was originally posted, we now have access to quite a reasonable variety of LiFePO4 and LiMn chemistry cells to utilize.
I would argue that the nature of a compact ecig really has LiMn and LiFePO4 written all over it. Considering the average atty resistance found in many units (~2.3 Ohm), anything less than a ~1AH rated LiCo cell would be operated at discharge rates in excess of manufacture recommendations. I can guarantee that there are numerous ecigs being sold with LiCo cells that are too small for the intended load.
What about shelf life and self discharge rates?
Almost unimportant to modders. We use 'em and abuse 'em. It is interesting, though, that li-ions only last about two years, whether used or just sitting there. You would be best served buying your li-ions from a distributor with high turnover. Any store selling nixie tubes wouldn't be my first choice.
Good advice on choosing a distributor with high turn-over to ensure fresh cells. In ecig applications, depending on the size of the cell and how "modded up" the atty situation is, I see no reason why some modern quality cells couldn't last several years of vaping. Especially the LiMn/LiFePO4 cells and large format modern LiCo cells. On the other hand, we'll probably continue to see the average life of the little AAAA cells to be pretty short lived.
What about the notoriously poor battery life?
In commercial ecigs, the battery size is approximately AAAA (8mm x 40mm) with about 180 mAh capacity. Those five second vapes approach 5C, so the commercials are sacrificing battery life for greater than rated output.
If a typical atty is in the 2-3 Ohm range, and we calculate for the enormous losses of energy that occur inside the cell when operated at these loads, I think you'll find that the actual C-rate (as calculated as a function of time) is probably around or in excess of 10C on many of the small ecigs.
But we are modders, so to hell with that. When a battery mod is AA size (10mm x 44mm) or greater,...
AAA=10mm x 44mm
AA=14mm x 50mm
...the battery capacity jumps to at least 750mAh, and the output falls to only a little greater than 1C, bringing it back into spec (usually 2C) and gain a much longer battery life (unlike the commercial cigs false claim of 300-500 charging cycles).
I agree 100% that the claims of several hundred cycles on the small ecigs is completely unrealistic when considering the loads presented. Having proof right at hand that the manufactures of the ecigs are being less than truthful on this specification should also be enough reason to raise an eyebrow regarding other claims or operation recommendations as well (more on this later.)
I would also point out, that even at the 14500 (AA) size cell, the loads produced by most attys are still in excess of 2C. The 750mAH rating, while not terribly exaggerated (I have seen some 14500 size cells from reputable sources deliver over 700mAH when tested at low drain rates), can not be used to derive the true "C" rate since the effective capacity at these higher rates is lower. Probably closer to 3C rate here for most 14500 cells.
Absolutely!
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Sorry But This Is Wrong: Maybe Thats Why No One Asked You.
I would like to take this opportunity to point out that the efforts made by mogur in trying to help piece together a compilation of useful information for the community was a net positive and does not deserve this kind of response. It is not constructive in any way.
RIGHT WAY On How To Charge Your Devices Battery: Always Follow The Manufacturers Battery Charging & Use Procedures. PERIOD!
For Proper Battery Information & Other Battery Information Please Use Wiki or Any Other Legitimate Site.
[/quote]
Wiki? Legitimate? that's funny... Yea there's a lot of good info on there but it always must be double checked for accuracy. Anyone can edit it with any good or bad information at any time.
The guys writing up the information and putting together the marketing side for these products are not engineers, they are just trying to get it to market. Most of this stuff comes out of china and this is a whole new market where most of the people selling it probably have no real clue about the true nature of the product being imported and sold. Heck, it's possible that those devices really do need 8 hours to charge up right, but that would be a major engineering flaw for a li-ion powered device.... I would say it's just as likely that the charging instructions were copy/pasted from instructions that came with consumer devices containing NiCD cells years ago.
There are manufacture recommendations that come from sources that can and should ordinarily be trusted. Go to the root of the parts and read the data sheets on the stuff that went into making these products, you can likely trust most of that information. Don't trust the middle-man. When you go and read THOSE data-sheets, you'll find out that the end-product "manufacture" recommendations for "use and charging" are at odds. It's also likely you'll find that the charger is not charging correctly to begin with.
I Am Sorry, I Can't Agree and This Is Still Wrong Battery Charging Information For E-Cigs & Most All Other Standard Type Lithium Batts & Other Batts!
Thats My Personal Opinion and It Happens To Be All The Battery Charging Manuals That Come With The E-Cigs That I Have (Over 2 Dozen Different E-Cigs).
It is in fact, the ecig instructions that are contrary to li-ion cell manufacture recommendations for charging. If the charger really does need those many extra hours "after the light turns green" to charge up all the way, then it is using an improper charging algorithm for li-ion cells. Li-Ion cells should under no circumstance be "trickle" charged.
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Overcharging is very dangerous on lithium ion cells. Even on sophisticated chargers, the manufacturers don't recommend leaving li-ion in the charger after the charge cycle is complete. If noobs listen to that four hours after the light turns green crap, needless risk is taken.
Correct!
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In that case, I do not agree with you. I recommend following the manufacturers suggestions. Let me explain how lithium ion chargers work. First, they charge at constant current until they sense the current fall off.
The charger holds a constant current until the charging voltage reaches the intended termination voltage, at which point the charger simply holds that voltage constant from there on forward. The current flowing naturally drops from the previous constant current phase of charging as the cell voltage comes into equilibrium with the constant voltage output of the charger...
Then they switch to a constant voltage mode and monitor that voltage until the cell reaches that voltage. At this point the cell has about an 80% charge, and the charging voltage masks the cell voltage, so the micro switches off the charger and senses the battery voltage via A/D converter. It then switches the charger back on and repeats this cycle every 20 seconds or so (depending on manufacturer), until the cell voltage reaches 4.2 volts.
The charge method described above, is essentially a CC only charge method that, depending on the charge rate, can wind up applying charge voltage well beyond the maximum recommended voltage for the cell. I have personally measured in excess of 4.4V (charging voltage, not state of charge) on chargers that use this method. It does not conform to li-ion manufacture charging requirements. The WF-139 and a few other popular Chinese li-ion cell chargers use this method. Technically speaking, it is a rather sophisticated way to charge, I would argue that it is equally as complicated to build as a regular CC/CV charger, too bad all that effort went towards a less than desirable charge algorithm.
The state of charge reached by the cell when the charge voltage reaches the intended termination voltage (4.20V in most cases) is determined by the charge rate and the resistance of the cell. On small cells with higher resistance, the cell may only be at 60% state of charge when the charger reaches 4.20V, on a large LiMn low resistance cell, it may be at 90%. (this is a purely academic point that doesn't really matter).
A few manufacturers vary this scenario, and instead use a shunt resistor to indirectly measure current via the voltage dropped by the shunt. Fairly uncommon, because the shunt is an extremely precision, low resistance, high wattage resistor and increases the manufacturing cost. In that event, the charging voltage is always constant and the topping charge occurs either when the charge timer expires, or the current falls below 10% of the current limit. The light doesn’t turn green on first voltage attainment, it only turns green after the cell is fully charged.
In most "proper" chargers that I have tested, this final method you describe is (roughly) the method used. Chargers like the Pila IBC for example conform to a proper CC/CV charge method very strictly, with proper termination triggered by a reduction in current flow to the cell. Also, a proper termination should completely isolate the cell from the charging circuit and allow the cell to rest. There should be no remaining trickle or float charge effect occurring, that final point is where almost all chargers that I have tested completely fail. To this day I have only tested 2 consumer oriented loose cell li-ion chargers that conform to all of the necessary requirements for a safe and proper charge.
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I wish someone would explain me why the DSE-801 user's manual specifies the batteries must remain on the charger for 8 hours prior to initial use. The exact Chinglish instruction says: "The first charging must be kept for 8 hours".
I noticed the light turns green quite quickly when initially charging newly delivered batteries.
Only way we're going to know what is really going on it to slip a DMM on the circuit and see what's happening actually. I'm surprised someone hasn't done this ... maybe someone has? If I had one of the little ecigs I would.
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I Really Don't Give A Flying Fluck. Your Wrong & You Can See The New Post's Coming Up Already With Battery Charging Confusion.
If You Know So Much You Would Have Known That Every Battery / Device Manufacturer & Engineer Has Their Specific Instructions For Their Batts, But Thats Why You Lost Out In The Business.
Back To The Books For You.
Now You Can See You Just Started Confusion & Questions, Hope You Answer To What You Started. I Tried Saving Your .... Yesterday Trying To Get The Thread Deleted, But They Decided To Let You Punish Yourself.
You Might Have A Few Hours Left To Delete The Post (You Have 24 Hours To Edit or Delete The Post If You Don't Know That, The Clock Is Ticking...) & Save Face, But Thats Up To You.
I am Not Trying To Bust Your Nuts, I Have Nothing Against You & Mean No Disrespect To You. So Take It As You Please.
So You Posted In The Modders Forum, Where Are Your Mods?
Anyone Who Has An E-Cig Will Know Your Wrong & Clueless.....
All The Real Lithium Battery Info Is Written By Real Experts Lithium-ion battery
From Wikipedia, the free encyclopedia
~Keep Vapin~!
How amazingly constructive. Thank you for your words of great wisdom. We have all benifited greatly.
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The voltages are all over the place in modders forums, because coils vary so much in resistance, and atomizers in design. I've seen commercial coils at 4.5 ohms, and I just disassembled a DX cigar with a 1.2 ohm coil. It would take almost four times the voltage to heat a 4.5 ohm coil to the same temperature as a 1.2 ohm coil. The reason is that current determines the temperature of the coil, and it takes four times the voltage to push an amp of current through a 4.8 ohm wire as it does through a 1.2 ohm wire.
Total power at the atty determines heat.
Examples:
12V / 16 Ohm = 0.75A, 0.75A x 12V = 9W heat energy.
6V / 4Ohm = 1.5A, 1.5A x 6V = 9W of heat energy.
3V / 1Ohm = 3.0A, 3.0A x 3V = 9W of heat energy.
All of the above scenarios would have the same amount of heat energy at the atty and similar vaping performance.
Most Li-Ions have a nominal voltage of 3.7, with a peak voltage of 4.2, and cut-off at 3 volts. But a commercial ecig usually stops vaping properly at about 3.5 volts anyway, and their micro disables the cell at ~3.3 volts.
It's probably cutting out under a load at 2.5V, and the cell is rebounding to ~3.3V open circuit. Regardless, most li-ion cells should be considered depleted if they are measuring below 3.5V open circuit.
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I just find it hard to believe that this myth about battery charging is continuing. mogur is right about the charging of protected Li-Ion batteries. The protection circuit is designed to protect the battery from over charging, trickle charging, and excessive discharging. I don't care what the manufacturer says about charging the batteries, it does not apply to Li-Ion batteries. Once the light on the charger turns green the charging circuit is terminated, period. You can leave the battery on the charger till hell freezes over and it wont charge the battery any more than it is after the circuit terminates.
This is of course assuming that they made the charger correctly, and it does actually properly terminate the charge.
You can do what you wish because there is no way you can harm these protected batteries with the battery charger. The protection circuit will always protect the batteries from abuse. So waste your time if you wish to, it wont hurt.
Kevin
I have tested numerous chargers that if left to their lonesome with a protected li-ion cell will trickle that cell up to the maximum the over-voltage protection will allow, which as you may recall from earlier in my very long post here, has been purposely set high for compatibility with another incorrect charging method. 4.35V is the typical cutoff for many PCBs on li-ion cells. Until the charger that comes with any particular ecig has been independently tested, it should be assumed that it is not doing things correctly.
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You are way over my head. I just have a simple question about the 18650's at DX. They seem to be less expensive for more mAh.
exp:
$8.18 for 2500 mAh (blue) vs. $8.79 for 2000 mAh (grey)
Is there any difference between the blue and grey? Reason for the pricing? What am I missing?
Thanks
Look for independent testing of the cells to make a purchase decision. I would highly suggest against buying the cheapest li-ion cells you can get your hands on. Historically speaking, the "xxxx-fire" brands of li-ion cells have been all over the map for quality, consistency, and capacity. In recent times, they seem to be getting better but they are not going to be as safe or long lasting as a good quality name brand cell.
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I too find that information to be confusing....
If the green light comes on and the battery is still trickle charging, all you are doing is charging the battery to it's max capacity. This is a bad thing for Lithium batteries.
The longevity of lithium batteries is affected by two things: Temperature and charge capacity.
You mean Temperature and SOC (state of charge), but yes....
[/quote]Lithium Batteries should be charged to 4.2 volts and then removed from charging. Charging batteries to 4.35 volts will HALVE the battery's life! [FONT=Verdana, Arial, Helvetica, sans-serif]
A continuous trickle charge above 4.05V/cell causes plating of metallic lithium that could lead to instabilities and compromise safety.[/quote]
Yes, Yes, and Yes. (with emphasis on perhaps the most overlooked problem with modern li-ion chargers)
[FONT=Verdana, Arial, Helvetica, sans-serif]Lithium-ion is designed to operate safely within their normal operating voltage but become unstable if charged to higher voltages. When charging above 4.30V, the cell causes plating of metallic lithium on the anode; the cathode material becomes an oxidizing agent, loses stability and releases oxygen. [/FONT]
And more YES and YES! (^listen to this guy!)
So, assuming that the charger is doing it's job, it should cut off the charge at 4.2 volts. Assuming it ISN'T, the battery itself should cut off at 4.3 volts.
In short, there's no good reason to spend 8 hours charging the battery before use.
One major point: Don't forget the effect on temperature on your batteries! If you are storing batteries for potential backup, keep them in the fridge with a 40% charge on them for longest life. DO NOT charge the battery and then put it on the shelf. DO NOT freeze batteries! The longer your battery stays at 100% charge, the shorter its life. (So, it's kinda a good thing that the batteries don't come pre-charged.)
If you'd like to follow the manufacturer's guidelines, then do so. But the original poster was correct, and for someone to say "Noone asked you" and "You don't know what you're posting" is both rude and foolish. There were alot better ways that could have been handled. A simple "As a supplier I always recommend following the manufacturer's guidelines" would have sufficed.
Well said! VERY WELL!
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CR123a, and it's rechargeable kin the RCR123a, are 3.0 volts.
The terms "16340" and "RCR123" are used interchangeably in the industry. In no case should either term be considered a reference to cell voltage or chemistry.
The only thing that can be derived absolutely about the term "16340" is that it is probably a cell, and it is probably 16mm diameter by 34mm length. Assuming anything above and beyond that can be very dangerous.
CR123 and CR123a are the same thing.
Ordinarily yes, but in the few days I have been on this forum, I see a HUGE population of people using the term "CR123" in places where it does not belong (referring to secondary cells).
I encourage ECF members to be VERY specific when discussing a particular cell. Name the size, the chemistry, primary, secondary, anything necessary to ensure that there is not going to be any confusion created.
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Are the 3.0 Volt CR123 the same as ICR123, RCR123, LIR123
Always check chemistry and voltage. Naming conventions, especially for the rechargeable 16340 size cells are very loose in the industry. I have seen all of those naming conventions used on cells that are technically different over the years.
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I'm sure this has been answered before but, how long should an 18650 2500 or 3000 mAh battery last after fully charged and put in a carry case? Does it drain on its on without use? I have plenty of batteries, but don't want to be away from home, thinking I have charged bats.
li-ion has very low self discharge rates. If you were intended on "storing" them for long periods of time but want them to be "ready to go" it would be best to discharge them down to ~4.0V before storing them. This would leave plenty of capacity still available (~80%) while reducing the effects of aging pretty dramatically compared to storing fully charged.
If you're talking about the ultrafire 3000s, they would be about the worst possible choice of 18650 cell for an ecig. The UltraFire 3000s have abnormally high internal resistance for the cell size and should be avoided.
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I asked this elsewhere in the forum, and then I came across this nifty thread. What a lot of excellent info! I'm hoping someone with expertise in this area can help me with the following dilemma:
I purchased some of the Tenergy LifePO4 RCR123A batteries from LitecigUSA and then later noticed that on the product description on the website, it says "Only charge these batteries with the Tenergy LifePO4 charger."
I charged them once with an AG-126 Lithium Ion Battery Charger that I purchased from MadVapes.
Do I really need to purchase a special charger for those batts, or will the one I already have be ok? It worked fine the first time, but I thought it might be prudent to check with those of you who know more about this sort of thing.
Any advice?
LiFePO4 cells can technically shrug off the overcharge with a low likelihood of causing danger, but they are still more apt to go "poof" if repeatedly charged in a charger designed for 3.7V cells that charge to 4.20V. Almost certainly charging that high will at minimum reduce cycle life a fair margin. LiFePO4 should be charged to ~3.6-3.8V.
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can you parallel a 1.5 v and 3.7 v battery to get 5.2 volts?
No... but you could put them in series and get 5.2V.
Technically speaking, there are ways that this type of thing could be done safely, but for now, just assume that they don't exist and don't do it unless you have a really pressing need or desire to do it, in which case, make it known and we can sort out what considerations you would need to have in place for it to work.
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in short madvapes from what i hear
heres the biggest that Ive seen:
https://www.madvapes.com/Protected-18650-Battery-3000-mah_p_2094.html This is the battery I would like also.
Ok, I was hoping that someone can tell me if is it ok to wire 2 18650's in parallel so that I can get close to double capacitance. Also I do have unprotected batts and would love someone to post a "how to build a protected circuit" guide. I have already built a passthrough box mod for use with a USB/ac plugin. Any help or links would be greatly appreciated.
BTW if someone already asked this question my bad.
Thanx everyone & happy modding!
Nothing wrong with putting li-ion cells in parallel as long as when they are assembled into their parallel battery, they share a reasonably similar state of charge at the time of making that connection. A dead cell joined in parallel to a fully charged cell *could* result in faster than safe charge rates for the depleted cell while one dumpes into the other. Once they are joined in parallel they will balance out to the same state of charge.
Doubling the number of cells in a parallel configuration should roughly double your vape time between charges, and also imrpove the performance of the vaping as it will balance the load of the atty across the 2 cells, the result is less voltage sag.
However , AVOID those 3000s like the plaugue!
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Well.... I think that sums up everything I wanted to say!
Eric
