Battery selection is crucial. And crucial not just from an electrical point of view but also safety. We could devote an entire book to batteries. Suffice it to say that they rarely live up to their ratings. Look for testing results from Mooch on ECF. Note as of June 2016 Mooch is also on PBusardos website. I look up the ampere draw of my Advanced Pernal Vaporizer (APV - a.k.a. "mod") then use the safe numbers from Mooch's testing chart to pick the appropriate battery. More capacity in maH is better but higher capacity batteries deliver less amperage safely. What I like about Mooch's test data is that he tests temperature along with current draw which is the primary key to battery safety. That plus he tests nearly every battery available. I like his testing so much that I have stopped doing my own. Mooch does an excellent job at testing batteries.
A lot of the companies rebrand OEM cells. But I am aware, there are lots of knock-offs out there too, so I buy my batteries from a reputable vendor like imrbatteries. As a BLUF, these are the batteries I consider for 18650; Sony VTC3/4/5, LG HB2/4/6, LG HD2, LG HE2/4, LG HG2, Samsung 20R/25R/30Q. There are others but these are readily available and have been tested and will safely support a 20amp continuous discharge. The LG HBs support a 30amp continuous discharge. The VTC3 supports 25amp continuous discharge. For 26650 the MNKE, BASEN, MXJO and AWT all support 25A continuous discharge but the MNKE all look the same so buy from a trusted source only. And as of June 2016, I highly recommend the Brillipower Green 26650 from Eightvape. With that said there are some unusual labels that I like too such as EFEST, Orbtronic, Keepower and AW but they get knocked off a lot. For 18350, AW red is the way I go.
Today we have the 20700 and 21700. I have stopped buying any mod that uses anything less than a 21700. My favorite 21700 is the Golisi S35. I like the iJoys as well for both 201700 and 21700. What I do not understand is why mods continue to hit the market that run on anything but a 21700. Nor do I understand why mods that sport Only 18650 are still being released. The Golisi S35 is undoubtedly the best lithium ion cell battery I have ever owned. And I have quite a few. Those cells are capable of current draw that no 18650 can match and have capacity that no 18650 can match at half that current draw. And I am making DIY flashlights that use the S35 as well.
There are five primary Li-Ion cell manufacturers, Sony Energy Devices Corporation (SEDC), Primearth Electric Vehicle Energy (PEVE), Lucky Goldstar (LG) Chem Power Incorporated (LGCPI), Sanyo, and Samsung SDI (Samsung, Display and Digital, Interface and Internet Component). PEVE was known as Panasonic EV Energy Company until 2010.
Most e-cigarettes use Lithium Ion batteries. Same types used in cell phones, laptops, cordless tools, flashlights, vacuum cleaners, hover boards, radios and etc. When you hear reports of e-Cigarettes blowing up or catching fire, it is the battery and the very same events happen with all those other items listed above that use Li-Ion batteries. These events are not common. Some products may experience the problem more than others due to the design. In other words, e-Cigarettes are not prone to catching on fire or blowing up any more than any other product that uses Li-Ion batteries. Further, I am not aware of a single e-Cigarette that is more prone than any other, unlike the Segway for example. Most Li-Ion battery fires are caused by improper use, storage, and maintenance which translated means discharging and charging. It is possible to discharge a Li-Ion too fast or too far and charge a Li-Ion too fast or too far. A proper design accounts for these limitations of the specific cell used. Which does not account for the human selecting the battery, charging the battery and using the battery and device. It is also possible to let a Li-Ion set too long without a charge increasing the likelihood of a catastrophic failure. It is also possible to charge them with a defective or incorrect charger. In order to mitigate these risks, I select the correct battery for the e-Cigarette (using the e-Cigarette's manufacturer amp draw data and Mooch's battery test results based on safe temperature margin given his amperage rating of that specific battery), using the e-Cigarette's built in USB charge port (if it has one) or a safe and reliable external charger (I never charge unattended), and proper handling of the battery itself (I don't put it in my pocket with keys, change or other metal items, do not sit it in sunlight, vehicle or anywhere it can get hot) and never let a Li-Ion battery set uncharged (and if it does then I will properly dispose of it). Further if a Li-Ion battery event does occur, I plan to drop the whole e-Cigarette and move away and call the authorities unless there is a Class D Fire Extinguisher nearby (water and other extinguishers can spread the fire instead of stopping it, the Class D will not stop the Li-Ion as it is self oxidizing, the Class D just prevents other stuff around the battery from catching on fire as the battery itself burns itself out). I do carry my spare batteries in a plastic battery box designed for them.
Lots of tests are done on batteries to determine their current delivery over time. A typical curve is shown below.
As they discharge, their voltage drops and their heat rises. And heat is the number one enemy to batteries. The faster they discharge the quicker they heat up. So batteries have a “C” rating. The C rating stands for capacity. But really it is discharge rate. The C rating is the maximum discharge rate. If you see 10C on your battery, it means it can be discharged at 10 times that batteries capacity. So if the battery is 1000mAh (1Ah) and has a C rating of 10, then it can discharge at 10A. However, the capacity rating and C rating are almost always over exaggerated. Mooch typically includes this knowledge with every cell he tests.
The charge a battery holds is expressed in milliamp hours or mAh. More capacity means longer vape time. So let’s assume a nominal Li-ion battery voltage of 3.65V. A 1000 mAh battery will provide 3.65Wh. Let’s assume you are vaping at 12W. Divide 3.65Wh by 12W multiply by 60 minutes in an hour and 60 seconds in a minute and that yields 1095 seconds. So let’s assume a little inefficiency and to make the math easier, really 1000 seconds of vape time. If your draw is 5 seconds than that means 200 puffs. Spread out over a typical 16 hour day that is 5 puffs every 24 minutes.
While not very useful, it certainly was a humorous calculation! Suffice it to say that I find 2000 mAh the minimum battery capacity I need. More is always better and it depends on how much I vape obviously. I always keep a battery on charge while I am vaping one. I like to swap out at the end of the day. If I can swap at mid-day, then a good start would be two at least 1600mAh batteries. But that’s just talking capacity.
What I do is match what battery I need to what the mod/APV needs. The maximum current a DNA-40 needs as specified on its data sheet is 16A. So a true 1600mAh 10C battery will work. Now you can use batteries with lower numbers but the DNA-40 may not be able to operate over its entire range and will show low battery even though I think it is charged. This happens with batteries that have been overheated or are at end of life. Most batteries will take 200-250 full charge cycles and then drop to 60% of their rating. It is always good to have a little margin. And given there are several batteries today that can deliver 20A continuously for a reasonable price, then buying a better battery than the mod needs is a good idea.
The “pulse” current delivery capability is different from its “continuous” current delivery capability. And some use the pulse for its C rating. And not all manufacturers use the same amount of time for rating pulse. The LG-HE2 can pulse 35A for 75s with a C rating of 14 and can deliver 20A continuous. While others “pulse” for a few seconds. Moreover, this pulse rating is being so twisted that it can be dangerous. Batteries used to be rated in terms of true continuous discharge. And that meant the battery was safe to discharge at that rate. Now with companies taking liberties with ratings, if you don’t get the right battery for your mod, there is significant risk of heat building up too rapidly. At best this means your hand gets warm and the battery is permanently damaged. At worst it means a potential health hazard that could result in the battery venting (a.k.a. what people call explodes).
There are batteries that the industry promotes as “safe” chemistry Lithium manganese (LiMN) which means reduced risk of venting with flame or explosion. I’m not sure I would call them safe maybe reduced risk. "IMR" simply indicates that LiMn2O4 is used, typically in the cathode. In other words, the chemicals in the battery a.k.a. “chemistry”. IMR does not necessarily indicate that the battery is safe nor that it has improved safety characteristics. So “safe” is relative. I also always ensure the mods battery compartment is vented and am aware of where that vent is, i.e. I keep that vent pointed safely away from myself and others just in case. The vent will control where the hot gasses exit the mod in case of a Li-ion battery “event”. And that assumes the mods battery compartment is structurally sound enough to confine the gases to only the vent hole.
Also note that IMR cells don’t usually have a protection circuit built in. These are called unprotected batteries. There are other batteries that do and are called protected. The protection circuit is normally a small fuse or resettable/auto resetting fuse which typically makes the battery a little longer and that can cause fitment issues with some mods/APVs. Unprotected cells are fine for APVs that do have protection built in to the APVs regulation board but maybe not so much for a mech. And with that said I have used the Panasonic Li-ion NCR 18650 batteries of totally different chemistries but at very low discharge rate. For example, the AW 3100 mAh ICR 18650 uses a Panasonic NCR18650A cell and a protection circuit. But these protection circuits can interfere with some regulated devices. The point is, I need to know what the APV/mod protection is and what battery it needs. The APV manufacturer should list recommended batteries. If it doesn’t, I stay away from them.
There are essentially two classes of Li-Ion cells, the name brands like Sony, Samsung, LG, Panasonic and then Chinese ones that may or may not be branded. Some makers use the high quality name brand cells and use good protection electronics in them conducting rigorous testing before putting their brand on them. AW is a fine example of this and I like authentic AW cells. But there are lots of AW knockoffs out there. So I only by from a trusted vendor. And I stay away from buying batteries on ebay. There are Chinese criminals using cells disposed of for recycling and/or poor quality then putting illegitimate copies of brand name labels on them like AW. These are extremely hazardous. At best they are factory rejects. To find out direct from AW who is an authorized vendor, I email firstname.lastname@example.org. The only place I have found where he posts and can buy them direct from him is cpfmarketplace.
The ICR (LiCoO2) chemistry is the most dangerous I know of. If used in an unprotected device like a mechanical mod there is a much larger probability that they will vent. And since it is going to need recharging you also want protection while charging. The ICR battery itself needs protection. Regardless, ICR cells need special chargers. The Nitcore Intelligent series handle protected ICRs. Under the ICR numbering schema are various chemistries including Nickel Manganese Cobalt (NMC) which is relatively safe (used in Sony, Samsung and LG cells) to Lithium Cobalt Oxide (LCO) which can be more volatile (used in LiPo). There are a lot of chemistries including INR, IMR, CGR and etc. Some have lower internal resistance and can therefore deliver more current than others that have higher internal resistance and deliver less current given a certain temperature the cell reaches under load. So I just stick to picking a battery from Mooch's test results that match the mod's requirements.
AW excepted, Chinese makers are notorious for fudging specs. And batteries are no exception. For example a 3000mAh ICR 18650 that actually tests at 2500mAh. The high quality cells such as the Panasonics, LG, Sony and Samsungs have accurate mAh ratings, so does the S35 Golisi accordingto Mooch's test data.
If I see someone advertising an 18650 over 3000mAh, it's a bogus rating. And those on eBay stating outrageous numbers like 4000mAh or more are counterfeit.
A Li-Ion battery “event” is "explosive" at first and then continues to fizz and melt down being dangerously hot. The initial "explosion" is dependent on the battery case design and can vary from a pop to a bang. I want to make it clear that the use of the word "explosion" is not really accurate. As case pressure mounts to the yield point of the vessel, the thin metal case or pressure vessel ruptures violently in a few milliseconds. This is what is meant by an "explosion". Though reportedly not enough to take fingers or hands off but can cause 3rd degree burns. Basically the chemistry is breaking down creating gases that build up pressure and then the battery case serving as a pressure vessel ruptures or ultimately yields spewing dangerously hot gases and chemistry that is continuing to break down. As the chemistry continues to break down, it produces a lot of thermal energy. Even one with little electrical charge left. It is usually the heat from charge and most prevalent discharge way above what the chemistry is capable of that triggers the breakdown. And the result is a sustaining thermochemical reaction. While it has never happened to me, I have seen reports of it happening and youtube videos and it is quite scary and dangerous. I don’t buy clones or knockoffs of batteries and chargers. This is not something I scrimp on.
None of these batteries should be discharged below 2.5 volts or cycle life/performance will be reduced. Maximum charge voltage is 4.25 volts. As long as they stay cool then there is infinitesimal risk. And keep in mind, they heat up during charge as well as discharge.
Most APVs today have a USB port on them and a USB charging circuit built in so they only need a USB charger. And those are typically limited to a half amp which is good. And there are USB adapters for the cig-a-like rechargeables and eGos. But some mods require the battery to be removed and placed in a charger. I prefer the Nitecore I series. Though the eFest LUC series work as well.
I use several different vendors/manufacturers’ batteries, Hohm Tech, AW, Keepower, Efest, Sony, Panasonic, MNKE, LG, and Samsung. They all work fine, no issues.
And now with the DNA-200, Lithium Polymer battery packs are commonly being used in OEM APVs. The DNA-200 uses a 3S or 3 cell lithium polymer battery pack and has a built-in, on the regulator board, balance charger so all I have to do is connect to the APV externally to a USB charger. The 3S LiPo in a DNA200 is connected to the balance charge port internally. For LiPo battery packs balancing chargers are a must. Anytime more than one cell is used even in APVs that uses multiple 18650s or 26650s the voltage of each cell and the charging of each cell must be accommodated. Charging multiple cells whether they are in series or parallel is a bad idea. A typical lead acid car battery is this very concept. The car battery has multiple cells in series and the cells are charged connected in series not per cell. And while explosive events with lead acid batteries are typically created by sparking and hydrogen gas build up, a single shorted cell can make the entire battery unusable. But the Lithium chemistry in e-Cigarette batteries makes them inherently even more dangerous if they are not charged per cell.
All the information contained in these pages are only the opinions of the author and the author is not an expert at anything.