The costs of running this huge site are paid for by ads. Please consider registering and becoming a Supporting Member for an ad-free experience. Thanks, ECF team.
Color
Background color
Background image
Border Color
Font Type
Font Size
  1. Because there are no absolutes when it comes to battery testing and battery ratings. The same "20A" battery, using the exact same test data, could be rated at anywhere from below 10A to above 40A. No one can look at the test data and give you "the" one and only battery rating.

    If a company thinks that its batteries should last 2,000 cycles then that "20A" battery could be rated at only 10A. If they don't care how long the battery lasts and just want the highest performance from it they might rate it at 40A. All those ratings use the same test data. But each tester or company has their own opinion of what's important.

    I base my methods of setting a rating on those used by Samsung, Sony, LG, and Panasonic/Sanyo. This allows for easy comparison of the batteries I test against batteries from these companies.

    To help prevent confusion though I am removing "In my opinion..." from the Bottom Line section of all future test reports. In each test report's disclaimer I state that my ratings are my opinion so it was redundant to say that elsewhere too.

    Because the same battery can be given a wide range of ratings it's important to find a tester you trust. Look at their test results, ask questions! Do they test each battery the same way? Do they tell you what criteria they use when setting ratings? Do they measure temperature? All these are critical for determining a battery's rating.
    RPadTV, anjelvape77, Baditude and 9 others like this.
  2. I'm often asked what batteries I would recommend. Here's the entire list. :)

    It does not mean I think your batteries are bad if you use ones not on this list!
    These are merely my personal recommendations for consistent performing and reliable batteries that can be purchased at a reasonable price.

    Note: The non-Samsung/Sony/LG/Panasonic/Sanyo batteries can change what is used under the wrap at any time.

    IMG_4813.jpg

    Click on the thumbnail above to download the table
  3. There are several things you can do to help your Li-Ion batteries last as long as possible before needing to replace them. Some are easy, some are quite inconvenient. Some have a big effect, some very little. But doing any of them can help slow down the aging and degradation of your batteries.

    Temperature
    • Don't overheat them. High temperatures are the biggest cause of battery damage and reduced battery life. Anything over about 45°C/113°F, what most would call warm, and your batteries start aging faster. The more time they spend being warm or hot, and the hotter they get, the more damage you're causing.
    • Don't use them when they're very cold, below -20°C/-4°F. The chemical reactions in a battery are a lot less efficient at low temperatures leading to poor performance. The sudden heating of the battery if used when cold can cause localized internal heating, possibly damaging the battery.

    Discharging
    • After using your battery, let it cool to room temperature before charging it.
    • Don't overdischarge them. Our batteries are rated down to 2.5V or lower but you can extend their life by staying above 2.8V-3.0V***. Going below 2.0V or so leads to metal being plated inside different parts of the battery, eventually causing an internal short circuit and possible bursting of the battery.
    • If you accidentally overdischarge your battery below 2.0V immediately recharge it at the slowest rate your charger supports. Once the battery rises up over 3.0V or so you can switch to your normal charge rate.
    • If battery has been at 2.0V for a while then it's probably damaged. It's not worth trying to use the "recovery" mode of your charger (if it has it) because the damage can lead to an internal short circuit later.
    • Li-Ion batteries do not need to be discharged occasionally all the way down in order to keep them in top condition. Li-Ion batteries do not suffer from "memory". This is only needed for NiCd (nickel-cadmium) or NiMH (nickel metal hydride) batteries.
    • Partial discharging and recharging multiple times is better for long battery life than discharging all the way down to where the mod indicates "low battery" and then recharging.

    Charging
    • After charging, let your battery cool to room temperature before using it.
    • Don't charge a battery that is below 0°C/32°F. It causes metal to be plated inside the battery eventually leading to an internal short circuit and possibly bursting of the battery.
    • Where possible, setting your charger to 4.1V will reduce stress on the battery and extend its life. But you will lose 10%-15% of the capacity of the battery.
    • Make sure the charger you use turns off once the charge is complete. Check the instructions for the charger you want to use.
    • Never use a trickle charger with Li-Ion batteries! The continuous holding of the battery at the trickle charge voltage damages it.
    • Don't overcharge them. To get the longest running possible time from a battery some chargers go up to as high as 4.27V. While this does result in a bit more vaping time before needing to recharge, it damages the battery. Most of the batteries we use are rated at up to 4.25V but even this is quite high. It's not dangerous until we're approaching 5V but battery damage starts occurring way below this.
    • Without a separate meter monitoring the battery's highest voltage before the charger stops it's hard to know what our batteries are actually being charged to. Our best option is to have our batteries spend as little time as possible fully charged and charge them just before using them. This usually isn't very convenient but it does extend battery life.
    • Charging at a slower rate is better, to a point. Most of our 18650 batteries have a "standard" charge rate of 1.0A-1.5A and a "rapid" charge rate of up to 4A. Charging at 0.5A might help extend the life of your batteries a bit but if the batteries are not getting warm at 1.0A then that's a good compromise between battery life and convenience. Going down to 0.375A or 0.25A won't help much versus charging at 0.5A.
    • Charge 18350's at 0.5A until you know that they aren't getting more than a bit warm.
    • Charge 26650's at 1.0A until you know that they aren't getting more than a bit warm. The better 26650's can be charged at up 2.0A without adversely affecting battery life.

    Miscellaneous
    • Storing batteries in the refrigerator doesn't make much of a difference in battery life unless you live in an area with high temperatures year around. It's not dangerous to refrigerate them but be sure to let them come to room temperature before opening whatever airtight wrapping/container you have them in.
    • If a battery wrap becomes damaged, replace it immediately. Replace the top insulator ring if it's also damaged.
    • Every time you buy batteries also buy battery boxes or sleeves, wraps, and top insulator rings. You...will...need...them.

    Additional Information

    ***This is the resting voltage, NOT the voltage "under load" that the battery drops to when being used. If your mod stops firing when the battery drops to 3.2V the battery can rise back to to 3.5V or even higher after resting for a while. This "resting voltage" is the important voltage, the one to be used when determining how low you are really discharging your batteries.

    While stopping at 3.4V, 3.6V, or even higher might extend battery life a bit you are missing out on a lot of additional vaping time that you could use before needing to recharge. That additional vaping time can be enjoyed every day for, at most, just the cost of one extra set of batteries a year. Stopping at these higher voltages won't hurt the battery though. Just let the batteries sit for an hour before charging to see what their true resting voltage is when deciding how low you want their voltage to go in your mod.
    Heartsdelight, Wisdom, Katya and 20 others like this.
    • When you start getting earlier and more frequent "low battery" alerts from your regulated mod even though you haven't increased the power.
    • When you notice that your mechanical/unregulated mod doesn't hit as hard, or for as long, as it used to (before needing to recharge your battery).
    • If your battery starts getting warmer during use or charging even though you haven't changed power settings or your coil resistance.
    • If your charger will no longer get to 4.20V before stopping. Make sure the charger is functioning properly and try switching charger bays before replacing the battery though.
    • If you see physical damage to the metal top or can of the battery. Things like dents and deep scrapes should not be ignored! A damaged wrap and top insulator ring can be replaced without needing to replace the battery.
    • If the battery vents and leaks fluid, even the smallest amount. Continuing to use a battery after it has vented can lead to the battery overheating and possibly going into thermal runaway and bursting.
    • If the battery has rusted badly. You don't need to worry about a few small spots but if they are pushing the wrap up or growing larger then replace the battery.
    • If the battery discharged down below 2.0V for a long period of time. Accidentally discharging down below that for a short period of time is ok. But if you left a battery unused for a long period of time and it's now dropped below 2.0V, replace it. You might be able to "recover" the battery with certain chargers but it's probably damaged and it's just not worth it.
    • There's no need to replace a battery on a fixed schedule, e.g., once a year. Those who use their batteries at high power levels might have to replace them every few months, or even sooner. Low power vapers can easily get a couple years of use out of their batteries.
    • Never throw your battery in the trash! Please recycle it. Many electronics or home improvement stores and vape shops will accept your batteries for recycling. First give the battery a couple of wraps in whatever tape you have to insulate it from any metal it might touch.
    • You do not need to replace a battery if you dropped it but there's no physical damage
  4. Inside each battery there are two things that can interfere with the flow of current in or out of the battery. The two of them together are called the internal resistance of the battery.

    Why is internal resistance important? It's what causes your battery to heat up and the voltage of your battery to sag.

    So what are the two things that add together to create the the battery's internal resistance?

    First, it's the actual resistance of the metal contacts and the internal structure that carries current through the battery (the electrolyte, separator, etc.). This resistance is typically only a few milliohms (thousandths of an Ohm) to a couple dozen milliohms.

    Second, it's the efficiency of the chemical reactions and flow of the ions through the battery. These ions can't be transported through the battery at any rate we want. As the current level rises there is a difference in the density of the ions in different parts of the battery. This change in the density and distribution of the ions results in a voltage difference between different points of the battery. We see this effect as a voltage change as soon as current flows. Knowing the voltage change and how much current is flowing we can use Ohm's Law to determine the equivalent resistance that would cause the same voltage change.

    These two resistances added together (one actual and one equivalent) give you the internal resistance of the battery...or the IR. The "DC IR", direct current internal resistance value, is the one we want to use. Since we pulse our batteries for up to several seconds we want to use the IR value measured when switching between two steady current values, one of them being zero amps in our case because we pulse our batteries on/off.

    The "AC IR" value often quoted in battery datasheets is lower but this is something we would use only when measuring performance in an unregulated PWM device. It's measured by pulsing the current at 100Hz or 1000Hz.

    The typical DC IR (which I'll just call IR) of a new Samsung 25R battery at room temperature is roughly 0.022-0.025 ohms. For a high-capacity 5200mAh 26650 battery the IR can be as high as 0.06 ohms. This is what causes the large voltage sag when we try to vape with these high-capacity 26650's at higher power levels.

    The IR of a battery affects how we vape by causing the voltage to sag during discharging and the voltage to rise during charging. Since these voltage drops or rises are just temporary, and aren't the true voltage of the battery, this can be a problem.

    So how does IR affect us when vaping? What other problems does it cause?
    We'll cover this in a future article.
    AciD_RaiN, DarrellG, Immortel and 9 others like this.
  5. The batteries I tested can change what's underneath the wrap at any time. Since there are no 26650's from Samsung, Sony, or LG available to us this can happen any time, even if the battery is not being counterfeited.

    This table was created to help you choose a battery based on discharge current levels that should be safe to vape with even if your regulated mod autofires or your mech mod's fire button is accidentally pressed for a long period. The recommendations in these tables also help to minimize damage to the battery that shortens its life due to overheating.

    It also contains pulse discharge performance data for experienced vapers who thouroughly understand their mod, Ohm's Law, and battery safety.

    You can find the test results, my comments, pictures of the cells, and the discharge graphs at:
    18350/18500 Battery Bench Test Results and New Ratings Table

    The recommendations in these tables are not the maximum power or current levels that the batteries can operate at! We pulse our batteries when we vape. This means we can use them at much higher levels than what the continuous current tests show. This table lists the actual continuous current rating for the battery, based on my testing, and how hard you can push them and still be safe in case of a device malfunction (which can discharge the battery continuously). You can push them beyond the recommendations in these tables. Each person has to weigh the risk and make their own decision as to how far they will go.

    This data is not just stuff gathered from around the Web. The grades are based on the results of my battery tests: List of Battery Tests | E-Cigarette Forum

    Note: The conclusions and recommendations I make here are only my personal opinion. Carefully research any battery you are considering using before purchasing.

    Caution: You are responsible for your own safety! These tables are only meant as a first step for you to use in narrowing down the best choices for the way you vape. Do not use them as the only source of information when picking a battery to use! This is especially true if you intend to use a battery at over 50% of its continuous current rating. I am not responsible for any damage or injury sustained by anyone using this table to select a battery.

    Links to my cell (battery) testing method and equipment:
    What's done for each cell test?
    Why bother with testing cell temperature?
    My cell testing equipment and setup
    Why do I sometimes rate a cell lower than other testers do?


    Other Battery Tests
    18650 Safety Grades -- Picking a Safe Battery to Vape With

    26650 Safety Grades and Pulse Performance Data



    PLEASE DO NOT CROP OFF THE EXPLANATIONS (FOR THE TABLE ENTRIES) AND MY WARNINGS WHEN DISTRIBUTING THE TABLE! IT MAKES THINGS VERY CONFUSING AND CAUSES A LARGE NUMBER OF PEOPLE TO ASK ME A LOT OF QUESTIONS ABOUT THE TABLE.

    image.jpeg

    Below is a list of the five different cells used for the 18350's I tested, their internal resistance, and their length.
    image.jpeg
    Leilani, Winblows, Titus Kho and 9 others like this.
  6. I wanted to outline some of the differences in the safety of the chemistries used in our batteries. The Battery Bro website has a fantastic explanation of the different chemistries themselves: Battery chemistry FINALLY explained.

    Before we go into the chemistry differences lets define the two different events that can occur if the battery is abused too hard; venting and thermal runaway.


    -- Venting --
    Venting is a purely physical process that releases excess pressure that forms inside a battery if it is discharged too quickly or charged at too high a voltage. Both of these situations cause excess gas to be created and that increases the pressure inside the battery.

    Each battery has a pre-weakened area of metal underneath the top contact. At a certain pressure level the weakened metal splits open and allows the pressure to escape. The solvent for the battery's electrolyte often oozes or sprays out too. This can be a problem because not only is it toxic but venting typically happens at around 130°C-160°C, which means the liquid is very hot.

    Venting can be a rather gentle event or it can be a pretty energetic spurting and spraying of gas and liquid. Be careful, that liquid is toxic and flammable! The battery does not burst and there are no sparks or flames. The amount of gas produced is relatively small and can usually be handled quite easily by the venting holes we see in mods.

    Once a battery vents, even just a little, it is ruined and should never be used again.


    -- Thermal Runaway --
    This is a catastrophic failure due to uncontrolled chemical reactions inside the battery. It always results in the bursting of the battery, sometimes quite violently, and can be accompanied by sparks and flames.

    As the temperature of the battery rises during a discharge, certain exothermic chemical reactions can start as the temperature goes above about 75°C. This is the beginning of the process that can lead to thermal runaway if these reactions are not stopped.

    If not being discharged too quickly, or the battery is being cooled a bit by ambient air flow or a metal mechanical mod tube, these new reactions can stabilize at a certain rate and not continue to increase the battery temperature. If the discharge current level is too high, or there's no cooling, then these reactions keep increasing the temperature of the battery. This causes more exothermic reactions to begin, which heats up the battery even more, which causes even more reactions to begin, and so on.

    As the battery reaches about 125°C the plastic sheet (the "separator") between the two sides of the battery, positive and negative, begins to melt. This can lead to small short circuits forming at different points in the battery. These short circuits increase the temperature at those points, further increasing the rate that the battery temperature rises.

    As the temperature continues to rise certain compounds start decomposing and releasing large amounts of gas. This increases the pressure inside the battery and, hopefully, leads to venting of the battery to release the pressure. But if the temperature and pressure buildup happens quickly enough, the battery won't vent in time.

    At about 230°C - 270°C the thermal runaway threshold temperature is reached. This is where there the materials inside the battery are decomposing incredibly fast. There is a huge buildup of gas and the battery bursts open, often ejecting its contents and throwing pieces of battery a long distance. Depending on the threshold temperature the solvent can also ignite, resulting in a fireball to accompany the shrapnel.

    While it can be quite violent, this isn't the explosion seen in a few videos that have made their way through the vaping groups and forums. Those explosions happen when a device doesn't have a pop off side panel or large open areas for the pressure to escape. The device holds back the gases for a bit but eventually it can't withstand the increasing pressure and it explodes.

    It is quite difficult, but not impossible, to bring the temperature of a battery up quickly enough to go into thermal runaway without it venting first. About the only way to do it is with a short circuit.

    Both venting and thermal runaway can take hours to occur or they can happen very quickly. You will typically be able to feel a battery getting hot before it vents but do not assume the same for preventing thermal runaway. That depends on a very, very fast rise in temperature, happening before the battery can vent. You might not feel the battery get hot first.

    How do we prevent thermal runaway then? Never allow our batteries to be short circuited! Keep your battery wraps and top insulating rings in perfect condition, replacing them when necessary. Never use an atomizer with a press-fit or spring-loaded 510 pin on a hybrid top mechanical mod. Always make sure that the 510 pin sticks out past the threaded stem of the atomizer.


    -- Differences in Battery Chemistry Safety --
    Each chemistry has different characteristics that make it safer or less safe than another. The attached table makes some basic comparisons between their safety.

    As the table outlines, ICR is the least safe, INR is safer, and IMR is the safest of the three. IFR batteries (lithium-ferrous-phosphate), like the ones from A123 , are the safest Li-Ion chemistry. Their lower nominal voltage, 3.3V versus 3.6V-3.7V, causes problems for regulated devices though. The "low battery" warning comes on much sooner than when using the higher voltage chemistries.

    The term "IMR" is being used by some battery companies as a generic term for any of their batteries that aren't ICR. These "IMR" batteries can be true IMR chemistry or one of the hybrid INR chemistries. While not accurate this isn't a safety issue as both IMR and INR are the safer chemistries.

    Not safe...safer. Any battery can be unsafe if abused enough.

    ICR batteries are not recommended unless you are very familiar with your device, Ohm's Law, and battery safety. The consequences of abusing these batteries is much, much worse than with IMR and IMR.

    image.jpg

    -- Conclusion --
    This can all sound quite ominous, making every battery sound like a bomb waiting to blow. While Li-Ion batteries can be dangerous if abused, we shouldn't fear them. A little knowledge and respect goes a long way towards making sure we never have problems.

    Know your batteries and vape safe!
    AciD_RaiN, Katya, Katdarling and 22 others like this.
  7. The batteries I tested can change what's underneath the wrap at any time. Since there are no 26650's from Samsung, Sony, or LG available to us this can happen any time, even if the battery is not being counterfeited.

    This table was created to help you choose a battery based on discharge current levels that should be safe to vape with even if your regulated mod autofires or your mech mod's fire button is accidentally pressed for a long period. The recommendations in these tables also help to minimize damage to the battery that shortens its life due to overheating.

    It also contains pulse discharge performance data for experienced vapers who thouroughly understand their mod, Ohm's Law, and battery safety.

    You can find the test results, my comments, pictures of the cells, and the discharge graphs at:
    26650 Battery Bench Test Results and New Ratings Table

    The recommendations in these tables are not the maximum power or current levels that the batteries can operate at!
    We pulse our batteries when we vape. This means we can use them at much higher levels than what the continuous current tests show. This table lists the actual continuous current rating for the battery, based on my testing, and how hard you can push them and still be safe in case of a device malfunction (which can discharge the battery continuously). You can push them beyond the recommendations in these tables. Each person has to weigh the risk and make their own decision as to how far they will go.

    This data is not just stuff gathered from around the Web. The grades are based on the results of my battery tests: List of Battery Tests | E-Cigarette Forum

    Note: The conclusions and recommendations I make here are only my personal opinion. Carefully research any battery you are considering using before purchasing.

    Caution: You are responsible for your own safety! These tables are only meant as a first step for you to use in narrowing down the best choices for the way you vape. Do not use them as the only source of information when picking a battery to use! This is especially true if you intend to use a battery at over 50% of its continuous current rating. I am not responsible for any damage or injury sustained by anyone using this table to select a battery.


    PLEASE DO NOT CROP OFF THE EXPLANATIONS (FOR THE TABLE ENTRIES) AND MY WARNINGS WHEN DISTRIBUTING THE TABLE! IT MAKES THINGS VERY CONFUSING AND CAUSES A LARGE NUMBER OF PEOPLE TO ASK ME A LOT OF QUESTIONS ABOUT THE TABLE.

    IMG_0611.jpg

    Click the thumbnail above to open the full size table.
  8. Calculating the current being drawn from the batteries in a regulated device can be very confusing. You can't do it the same way as you would for a mechanical/unregulated device and there are so many different battery configurations; single, dual parallel, dual series, triple series, etc.

    The way I keep it all sorted out is to remember that, in a regulated mod, the coil isn't connected to the battery. The regulator is. To calculate the current being drawn from each battery when using variable-wattage (VW) mode you need to calculate the maximum wattage each battery supplies.

    Here's how I do it...
    As an example, the RX200 has a maximum wattage rating of 200W. Since it uses three batteries that means each battery supplies 200W / 3 = 67W. For dual parallel or series 150W devices each battery supplies 150W / 2 = 75W. You use this method for series or parallel devices, it doesn't matter.

    Once you have the maximum wattage for each battery then you can use the following formula to determine the maximum amount of current that can be drawn from each battery...

    Max Amps Per Battery = Max Wattage Per Battery / Minimum Voltage Per Battery

    For the RX200 the minimum possible cutoff voltage is 9.0V, which is 3.0V per battery (unless you set the cutoff higher). For most other devices the minimum is 3.2V or 3.1V per battery. Let's use the Sigelei 150W TC device as an example. This device has a minimum battery voltage of 6.4V, which is 3.2V per battery...

    Max Amps Per Battery = 75W / 3.2V = 23.4A

    So you want a battery that can safely supply 23.4A of current if you're using the mod at its maximum rating of 150W.

    I should add that to get as close as possible to calculating the max current being pulled from your batteries you should add an additional 10%. This will account for the inefficiency of the regulator. For example, if your device draws 23.4A then add 2.34A for a total of 25.74A. Not a big difference, but it's there. That changes the equation to...

    Max Amps Per Battery = (Max Wattage Per Battery / Minimum Voltage Per Battery) / 0.9

    If you know you will not be exceeding a particular wattage that is less than the maximum then you can use that wattage in the equation instead. This often means you're able to use a higher capacity battery like the HG2 or 30Q instead of a high current rated, but lower capacity, battery like the VTC4 or HB6. It's worth doing the math to find out.

    This works for series or parallel devices. It does not matter how they are connected as we are already taking that into account when we calculate the max power for each battery.

    It takes much longer to explain all this than it does to actually calculate the amount of current being drawn from your batteries. I hope this helps make the very confusing process of determining how much current is being drawn a little bit easier. :)
  9. Have you considered using a battery because of its high pulsed current rating? At first glance the pulse rating seem to make a lot of sense. After all, when we vape we don't run our batteries continuously. We only use them for a few seconds at a time. And considering how much higher the pulse ratings are, versus the continuous current ratings, it's very tempting to choose a battery based just on its pulse rating.

    Don't!

    There are no standards for these pulse ratings. One battery reseller could base their rating on taking 4 second draws every minute and another might base their rating on 10 second draws every 20 seconds. These two examples will result in very different temperatures and performance. The same battery could get a 40A rating one way and a 30A rating the other way. This makes comparing batteries by their pulse ratings very difficult, if not impossible.

    But that's not the worst of it!

    What happens if our regulated mod autofires or our mechanical mod's button gets stuck on or accidentally pressed in our pocket? If we have set up our mod with a low resistance coil that forces us to only rely on a battery's pulse rating, we could be in big trouble. We could easily overheat the battery, causing it to vent or perhaps even burst.

    Choosing which battery is best to use based on pulse ratings is not only practically impossible, it can be unsafe too.

    So how should you choose a battery to get both the most power for your mod and still be safe? Either go by the continuous discharge rating (CDR) or find a reviewer that tests batteries beyond the CDR and records temperatures to know when it becomes unsafe. But for longer battery life, consider running your batteries below their CDR. It adds a greater safety margin as the batteries age and lets them run cooler.

    I have set up a table of safety "grades" for all the batteries I have tested to date. This table shows you what discharge current levels are safe and which might be dangerous for each battery. It can be used as part of choosing which battery might be best for you:

    18650 Safety Grades -- Picking a Safe Battery to Vape With

    For more detailed information on the batteries I've tested, here's a list of links to the results of each test:

    List of Battery Tests

    If you're considering using a battery that has a rating above 30A, check this out before you buy them:

    There are no 18650 batteries with a genuine rating over 30A!
  10. We've all seen them, the batteries with 35A (35 amp) or higher current ratings. And it seems that they would be the perfect choice for mech (mechanical mod) users or really low ohm coil builds, doesn't it?

    Except for the fact that as of July 2015 January 2016 there are no 18650 batteries rated at above 30A continuous available to us vapers!

    Batteries are manufactured by only a handful of companies like Samsung, Sony, and LG. It takes millions of dollars to start up even a modest battery production line. The companies you see selling these high-amp batteries are just too small to be able to afford that kind of investment. So where do they get the batteries from? The established battery manufacturing companies like Samsung, Sony, and LG!

    These smaller companies buy the batteries, rewrap them (i.e., they put their own "wrap", or sleeve, on them), boost up the current and capacity ratings, boost up the price too, and sell them as high performance batteries. This is how we know that there are no 35A or higher rated 18650 batteries out there. None of the big battery companies make them!

    Since these battery rewrapping companies use the same batteries that we can buy at a lower price with the original manufacturer's wrap still on them, why should we buy them? In my opinion, no reason at all unless they are the only ones you can get.

    Can these 35A and higher rated batteries actually be used at those high current levels? Technically, yes. Those high current ratings are just "pulse" ratings, passed off as continuous current ratings. This means those batteries can only be used at those current levels for short pulses of current. You might be thinking that this isn't a problem because we only vape for a few seconds at a time. But using them like that isn't safe.

    Since battery rewrapping companies typically exaggerate the ratings by quite a lot, or pass off the pulse rating as the continuous current rating, we don't know how hard we can safely run those batteries continuously. And this can lead to big problems if we have a regulated mod that autofires or if we have a mech mod and its button sticks or is accidentally pressed in our pocket. Without knowing the battery's true continuous current rating this could easily lead to the battery spraying hot, toxic stuff inside your mod ("venting"). Or worse, it could cause the battery to go into "thermal runaway" where the temperatures rise tremendously and the cell violently bursts open.

    To help you figure out how hard you can run different batteries, take a look at my 18650 Safety Grades table. It can help you narrow down your choices:

    18650 Safety Grades -- Picking a Safe Battery to Vape With | E-Cigarette Forum

    For some great information on batteries and battery safety (and many other topics), see Baditude's blogs:
    (18) Baditude's Blogs | E-Cigarette Forum

    And don't be afraid to just ask for advice here at ECF. If you see a battery that you want to buy, but aren't sure if it's safe to use in your mod, please ask us! We want to see everyone vaping safely and will be glad to help.

    So, are there 30A batteries? Only one, the LG HB6 1500mAh 18650. You can see the classic tradeoff between capacity (number of mAh) and the current rating here. Typically, if you want high capacity you can't have a high current rating. And vice-versa. If you see a battery with both, check around for test results or a review before buying it.

    There are other batteries that handle almost as much current as the HB6 though. I recommend the Sony VTC4 as the best all around battery for over 20A. At around 20A it's hard to beat the Samsung 25R. Just be sure to buy from a reliable vendor that carries genuine batteries, like one of these (in no particular order)...

    illumn.com
    rtdvapor.com
    orbtronic.com
    liionwholesale.com
    imrbatteries.com

    So be careful of these batteries boasting that they're rated above 30A and vape safe!

    This blog is my personal opinion only and is based on my battery testing results and knowledge of the batteries that are available on the market. If you are a vendor or supplier with a battery you are confident has a continuous discharge rating over 30A, I would be happy to test it and post the results.
  11. Which battery is safe to vape with?

    This table was created to help you choose a battery based on discharge current levels that should be safe to vape with even if your regulated mod autofires or your mech mod's fire button is accidentally pressed for a long period. The recommendations in this table also help to minimize damage to the battery that shortens its life due to overheating.

    The recommendations in this table are not the maximum current levels that the batteries can operate at!
    We pulse our batteries when we vape. This means we can use them at much higher levels than what the continuous current tests show. This table only lists the actual current rating for the battery, based on my testing, and how hard you can push them and still be safe in case of a device malfunction (which can discharge the battery continuously). You can push them beyond the recommendations in these tables. Each person has to weigh the risk and make their own decision as to how far they will go.

    This data is not just stuff gathered from around the Web. The grades are based on the results of my cell tests: List of Battery Tests

    This table will be updated as additional batteries are tested.

    Caution: You are responsible for your own safety! The conclusions and recommendations I make here are only my personal opinion. Carefully research any battery you are considering using before purchasing. This table is only meant as a first step for you to use in narrowing down the best choices for the way you vape. Do not use it as the only source of information when picking a battery to use! This is especially true if you intend to use a battery at over its continuous current rating. I am not responsible for any damage or injury sustained by anyone using this table to select a battery.

    IMG_0775.jpg

    Click on the thumbnail of the table above to open the full-size table
    abdulaziz, Sky R, foundway and 72 others like this.
  12. Here are links to the battery tests that I have done to date and links to my test methods and equipment. I'll keep this list updated as more tests are completed.

    Note: The conclusions and recommendations I make here and in the links below are only my personal opinion. Carefully research any battery you are considering using before purchasing.


    900mAh LiPo Pack Test Results

    1800mAh LiPo Pack Test Results

    20650/20700/21700/21-70 Test Results

    18350 Test Results
    The above tests include the following cells:
    Aosibo Red 800mAh
    AW Red (button top) 800mAh
    AWT Yellow 800mAh
    Brillipower Green 900mAh
    Efest Purple V2 (button) 700mAh
    Efest Red/Silver 800mAh
    Imren Blue 800mAh
    Keeppower Black 750mAh
    MXJO Red/Silver 800mAh
    MXJO Yellow 700mAh
    Tensai Blue 700mAh
    Vappower Green 750mAh

    Additional 18350 tests:

    18500 Test Results

    26650 Test Results
    The above tests include the following cells:
    AWT Yellow 75A 4500mAh
    AWT Red 45A 5200mAh
    Basen Black 30A 4500mAh
    Efest Purple 32A 3500mAh
    Efest Green 20 4200mAh
    Efest Purple 40A 4200mAh
    Efest Purple 15A 5200mAh
    Imren Orange 60A 3600mAh
    Keeppower Black 30A 4200mAh
    Keeppower Black 20A 5200mAh
    Kidney Puncher 20A 4000mAh
    MNKE Orange (narrow) 35A 3500mAh
    Orbtronic 20A 5200mAh
    Vappower Green 40A 4200mAh
    Vappower Green 20A 5200mAh

    Additional 26650 tests:

    18650 Shootout Test Results


    18650 Bench Test Results

    Eizfan 40A 3000mAh 18650 Bench Test Results...only a 20A battery, probably a 30Q

    EnerCig EC-C5A 35A 2500mAh 18650 Bench Test Results...a fantastic battery, Sony VTC5A rewrap

    EnerCig EC-NSX 22A 2600mAh 18650 Bench Test Results...a great battery, Sanyo UR18650NSX rewrap

    EnerCig EC-C6 25A 3000mAh 18650 Bench Test Results...a fantastic battery, Sony VTC6 rewrap

    Energy Vap 35A 3000mAh Bench Test Results...a dangerously overrated 20A 2700mAh battery!

    Energy Vap 20A 3000mAh (formerly 35A 3000mAh) 18650 Bench Retest Results... only a 2500mAh battery!

    Enook 40A 2600mAh 18650 Bench test Results...ridiculously overrated, poor performing 20A battery

    Enook 40A 3100mAh 18650 Bench Test Results...just 20A and same as Enook 3000mAh battery?

    Enook 40A 3100mAh 18650 Bench Test Results...just 20A and same as Enook 3000mAh battery?

    Enook 40A 3200mAh 18650 Bench Test Results...only 10A, shame on you Enook!

    Enook 35A 3600mAh 18650 Bench Test Results...a shamefully overrated 10A battery!

    ESYB Green 20A 3000mAh 18650 Bench Test Results...tested as 19A/2900mAh, seems to be HG2

    ESYB Green 12A 3500mAh 18650 Bench Test Results...tested 12A/3300mAh, seems to be NCR18650GA

    Golisi Gold G30 25A 3000mAh...bit overrated, appears to be HG2

    Gpower Yellow/Black 20A 2500mAh 18650 Bench Test Results...accurately rated, poor performing

    Gpower Yellow/Black 25A 2600mAh 18650 Bench Test Results...a poor performing 19A 2500mAh battery

    Gpower Yellow/Black 20A 3000mAh 18650 Bench Test Results...a poor performing 17A 2800mAh battery

    Hibatt Orange 35A 2500mAh 18650 Bench Test Results...only a 20A battery, probably a 25R

    HohmLife 36.3A 3077mAh 18650 Bench Test Results...only a 20A- battery but a great one, equal to HG2

    HohmWork 40.6A 2531mAh 18650 Bench Test Results...only a 20A battery but great, better than HE2

    Imren Orange 30A 2100mAh 18650 Bench Test Results...only a 20A+ battery[/COLOR]

    Imren Purple 40A 2500mAh 18650 Bench Test Results...a 20A cell that runs very hot

    Imren Yellow 40A 2000mAh18650 Bench Test Results...a decent 20A battery, may be an HD2

    Imren Gold 20A 2500mAh 18650 Bench Test Results...an accurately rated battery!

    Imren Leopard 50A 2600mAh 18650 Bench Test Results...just a 20A rewrap

    Imren 40A 3000mAh 18650 Bench Retest Results...only a 17A battery, damaged at 30A

    Imren Gold 30A 3000mAh 18650 Bench Test Results...a ridiculously overrated battery

    Imren Green 40A 3200mAh 18650 Bench Retest Results...just 17A, the purple Imren 3000mAh rewrapped!

    Imren Green 40A 3200mAh 18650 Bench Retest Results...now 10A, shame on you Imren!

    Imren Yellow 25A 3400mAh 18650 Bench Test Results...just a 12A battery

    The green 30A 3500mAh Imren is a 10A battery!

    IronSmith 40A 2050mAh 18650...hugely overrated, VTC4 performs better + hits harder

    Juicebox 22.5A 1500mAh 18650 Bench Test Results...a 20A 1600mAh battery, damaged at 25A

    Kdest Black 35A 2500mAh 18650 Bench Test Results...ridiculously overrated, one was a dud

    Kdest Beige 35A 2800mAh 18650 Bench Test Results...shamefully overrated, just a 10A battery!

    Kdest White 40A 3100mAh 18650 Bench Test Results...preposterously overrated, absurd pulse rating

    Kdest Black 15A 3500mAh 18650 Bench Test Results...just a 10A 3400mAh battery

    LG HB2 30A 1500mAh 18650 Retest Results...a great 30A battery, about equal to VTC3

    LG HB4 30A 1500mAh 18650 Bench Test Results...a fantastic 30A battery, beats HB6 when pulsed!

    LG HB4 "Mustard" 30A 1500mAh 18650 Bench Test Results...a great 30A battery, better than brown HB4

    LG HB6 30A 1500mAh 18650 Bench Retest Results...a fantastic cool-running true 30A battery, but low capacity

    LG HB6 Pink 30A 1500mAh 18650 Bench Test Results...great 32A/1500mAh battery, better than ivory HB6

    LG HB7 15A 1500mAh 18650 Bench Test Results...a low capacity 17A battery

    LG HD2 25A 2000mAh 18650 Retest Results...a great 25A battery, equal to VTC4

    LG HD2C 20A 2100mAh 18650 Bench Test Results...a 22A/2200mAh battery, better than the HD2

    LG HD4 Salmon 18650 Bench Test Results...a 25A/2100mAh battery, in between HD2 and HD2C

    LG HE2 20A 2500mAh 18650 Bench Retest Results...a very good 20A battery

    LG HE4 20A 2500mAh 18650 Bench Retest Results...a good 20A battery but 25R5 is better

    LG INR18650-HG2 20A 3000mAh Bench Retest Results...a great 20A battery!

    LG MH1 10A 3200mAh 18650 Bench Test Results...safe at 10A but suffers damage

    LG MJ1 10A 3400mAh 18650 Bench Retest Results...an good 10A battery

    ModWorx 38A 2100mAh 18650 Bench Test Results...only a 20A battery, collapses at 38A

    MXJO Yellow 30A 1600mAh 18650 Bench Test Results...just a 21A battery but 2100mAh

    MXJO Yellow 35A 2500mAh 18650 Bench Retest Results...a ridiculously overrated 20A/2400mAh battery

    MXJO Yellow 35A 2600mAh 18650 Bench Test Results...a 19A/2500mAh battery, gets dangerously hot

    MXJO Yellow 35A 2800mAh 18650 Bench Test Results...only a 20A battery but equals the 25R

    MXJO Yellow 30A 2900mAh 18650 Bench Test Results...a preposterously overrated 10A/2700mAh battery

    MXJO Yellow/Silver 35A 3000mAh 18650 Bench Retest Results...a dangerously overrated 20A battery!

    MXJO Yellow/Silver 35A 3000mAh 18650 Bench Retest Results...still an overrated battery

    MXJO Yellow/Silver 35A 3000mAh 18650 Bench Test Results...only a 15A-20A battery, but near an HG2

    MXJO Yellow 20A 3500mAh 18650 Bench Retest Results...ridiculously overrated, ruined at 20A!

    MXJO Green/Silver 20A 3500mAh 18650 Bench Test Results...still an 11A/3300mAh battery

    Nitecore 30A 2100mAh 18650 Bench Test Results...useless 30A rating, only 22A

    Nitecore 38A 2100mAh 18650 Bench Test Results...useless 38A rating, only 23A

    Nitecore 35A 2500mAh 18650 Bench Test Results...useless 35A rating, only 20A

    Nitecore 40A 2600mAh 18650 Bench Test Results...ridiculous 40A rating, only 20A

    Nitecore 35A 3100mAh 18650 Bench Test Results...only 20A 3000mAh

    Orbtronic ORB25 21A 2500mAh 18650 Bench Test Results...a low-capacity 15A+ battery

    Orbtronic SX22 22A 2000mAh 18650 Bench Test Results...a 22A battery, may be a 30Q

    Orbtronic SX30 30A 2100mAh Flat-Top 18650 Bench Test Results...just a 20A cell

    Orbtronic SX30 30A 2100mAh Button-Top 18650 Bench Test Results...a 23A cell at best

    Panasonic CGR18650CH 10A 2250mAh 18650 Bench Test Results...a so-so 10A battery

    Panasonic NCR18650B 4.9A 3200mAh 18650 Bench Test Results...a so-so 4.9A battery

    Panasonic NCR18650BD 10A 3000mAh 18650 Bench Test Results...an good 10A battery

    Sanyo NCR18650GA 10A 3300mAh 18650 Bench Retest Results...a great 12A battery

    Panasonic NCR18650PF 10A 2680mAh 18650 Bench Retest Results...an ok low capacity 10A battery

    Pegasus Vapor Academy Type A 10A 18650 Bench Test Results...a very good 10A battery, probably MJ1

    Pegasus Vapor Academy Type B 15A 3000mAh 18650 Bench Test Results...rated it 19A, probably a 30Q

    Samsung 15L 18A 1500mAh 18650...underrated but not a great performer

    Samsung 15M 23A 1500mAh 18650...30A battery but HB6 better at high current

    Samsung 20R 22A 2000mAah 18650 Bench Retest Results...a good 20A battery that never overheated

    Samsung 22P(M)...underrated but a poor choice for vaping

    Samsung 25R Blue Wrap 20A 2500mAh Bench Test Results...a great 20A cell

    Samsung 25R Green 20A (25R5) 2500mAh 18650 Bench Test Results...a great 20A battery

    Samsung 25R (6M Variant) 18650 Bench Test Results...25R5 is slightly better

    Samsung 26F 5.2A 2600mAh Bench Test Results...just not worth it

    Samsung 30Q 20A 3000mAh 18650 Bench Retest Results...a great 20A/3000mAh battery!

    Samsung 35E 3500mAh 18650 Bench Test Results...a so-so 8A battery

    Sanyo NCR18650GA 10A 3300mAh 18650 Bench Retest Results...a great 12A battery

    Sanyo UR18650NSX 20A 2500mAh 18650 Bench Test Results...a great 22A battery, about equal to the 25R5

    Shockli Blue 30A 2400mAh 18650 Bench Test Results...a poor performing 17A battery

    Shockli Blue 35A 2500mAh 18650 Bench Test Results...just a 20A battery, looks like 25R

    Shockli Blue 35A 3000mAh 18650 Bench Test Results...just a 20A battery, looks like a 30Q

    Sigelei 35A 2500mAh 18650 Bench Test Results...shame on you Sigelei!

    Sigelei 35A 2500mAh 18650 (with GPower Cell) Test Results...too inconsistent to test

    Sony VTC3 1500mAh 18650 Retest Results...a hard hitting 28A 1600mAh battery

    Sony VTC4 2000mAh 18650 Retest Results...a great 23A 2100mAh battery

    Sony VTC4 2000mAh "use only in packs" 18650 Test Results...identical to other genuine VTC4's

    Sony VTC5 2500mAh 18650 Retest Results...a great 20A 2600mAh battery

    Sony VTC5A 2500mAh 18650 Bench Test Results...a fantastic 25A battery!

    Sony VTC6 15A 3000mAh 18650 Bench Test Results...a great battery, equaling HG2/30Q

    SubOhm SE 20A 2500mAh 18650...accurately rated, probably a 25R

    SubOhmCell 35A 2800mAh 18650 Bench Test Results...only a 15A-20A 2500mAh battery

    Tesiyi 40A 2600mAh 18650 Bench Retest Results...changed cells, a very good 25A/2500mAh

    Vamped 40A 2300mAh 18650 Bench Test Results...a 20A/1800mAh battery, no higher

    Vape Haze 38A 2600mAh 18650 Bench Test Results...a good 20A battery, damaged at 30A-35A

    Vappower Green 35A 2500mAh 18650 Bench Test Results...a 20A battery, no higher

    Vappower Green 30A 3000mAh 18650 Bench Test Results...only 15A+ battery, but good capacity

    VRK 20A 3000mAh 18650 Bench Test Results...accurately rated, looks like HG2

    VRK 10A 3500mAh 18650 Bench Test Results...accurate current rating, looks like NCR18650GA

    Westinghouse 2000mAh 18650 Bench Test Results...only a 7A battery

    X2 Power 37.5A 2400mAh 18650 Bench Test Results...only an average 20A battery, damaged at 25A

    XTAR XTVTC4 25A 2200mAh 18650 Bench Test Results...it's not a VTC4!

    XXX 20A 3000mAh Bench Test Results...an accurately rated battery, looks like 30Q

    XXX 40A 3100mAh 18650 Bench Test Results...exaggerated ratings, looks like 30Q

    david4500, Bramsaurus, Katya and 43 others like this.
  13. Updated 10/24/15 to include pulsed discharge tests.

    For every cell I test, these are the steps I follow...

    Continuous Current Tests
    • I use two of each cell for testing.
    • Photograph the wrap from one cell and top if a button has been spot-welded on.
    • Remove the wrap and photograph the case, top, and bottom.
    • Attach the thermocouple (temperature sensor) halfway down the cell with Kapton tape, making sure to cover the tip of the thermocouple to prevent any flowing air from cooling it.
    • Clean the test rig contacts with a Scotch-Brite pad and then a 90% alcohol wipe.
    • Mount the cell in the low-resistance test rig.
    • Charge 18650's and 26650's to 4.20V at 2.5A until the current drops to 100mA. 18350's are charged at 0.5A unless the manufacturer specifies a higher rate.
    • Run three constant-current (CC) discharges down to 2.80V to check basic cell functionality, including capacity and temperature. 18650's and 26650's are discharged at 10A. 18350's-18500's are discharged at 5A.
    • If all three discharges are essentially identical then I continue. If something keeps changing for each discharge I keep running them until the cell's performance has stabilized. So far, every cell has stabilized within three discharges.
    • For each discharge I measure the actual current level using a 0.25% tolerance current shunt and a Fluke 8846A meter. This not only confirms the starting current level but by using the min/max/avg functions of the meter I can confirm that the current level has not drifted.
    • Run CC discharges, down to 2.80V, at every 5A increment above that until the cell reaches 100°C or the voltage just quickly collapses.
    • Note the maximum cell temperature reached for each discharge.
    • After each discharge let the cell cool to below 40°C before recharging.
    • Recharge each cell to 4.20V, stopping when the charge current has dropped to 100mA.
    • Determine the cell's continuous discharge rating (CDR) by noting the current level that brings the temperature closest to the 78°C average (74°C-82°C range) I measured for the Samsung, Sony, LG cells I tested at their CDR.
    • Run an additional two CC discharges at the cell's CDR to check for voltage sag, loss of capacity, or increasing temperature. These are all signs of cell damage and indicate that the cell's rating is too high.
    • Run an additional two CC discharges at 5A above the cell's CDR to check for voltage sag, loss of capacity, or increasing temperature. These are all signs of cell damage and indicate that it's being discharged at beyond its rating. It also gives us an idea of hard it can be abused.
    • Take the second cell, run the three initial discharges, and then discharge at 10A and at the CDR of the cell. If the results are within 2% of the first cell then the first cell's discharge graph is used. If the discharges of the second cell are different from the first I do not post any test results until I can source another set of cells to test and compare.

    Pulsed Current Tests
    • Discharge the second 18650 or 26650 cell at 30A, each pulse is 5 seconds on/30 seconds off, down to 2.50V. 18350-18500 cells are started at 10A.
    • A lower cutoff voltage is used for the pulse testing to give those cells that have a significant increase in voltage when hot (due to lowered internal resistance) a chance to warm up.
    • Run pulsed current discharges, down to 2.80V, at every 5A (for 18350-18500) or 10A (for 18650-26650) increment above that until the cell reaches 100°C or the voltage drops to 2.50V for the first pulse.
    • After each discharge let the cell cool to below 40°C before recharging.
    • Recharge each cell to 4.20V, stopping when the charge current has dropped to 100mA.
    • Note the maximum cell temperature reached for each discharge.

    I don't have a standard yet for determining the pulse rating for a cell. When I have enough pulsed current discharge data I will give each cell I test a pulse rating. In the mean time you can view the discharge graphs to see what the voltage drop is for the cells I have been testing recently. All of the Samsung, Sony, and LG cells are being retested to add this pulsed current data.


    Important Notice!
    Testing batteries at their limits is dangerous and should never, ever be attempted by anyone who has not thoroughly studied the dangers involved and how to minimize them. My safety precautions are the ones I have selected to take and you should not assume they will protect you if you attempt to do any testing. Do the research and create your own testing methods and safety precautions.
    Ariel_MX, CG138, dcfluegel and 3 others like this.
  14. As an example, suppose one cell had a 30A continuous discharge rating (CDR) and another cell had a CDR of 20A. The 30A cell sounds like it would be a better choice for use in a device that draws lots of current. But if it rises to a temperature of 120°C delivering that current, that cell is overrated and will have a very short life...if it doesn't vent or burst first. The 20A cell might actually be a better choice depending on how hot it gets. Something you could determine if you had the temperature data.

    I feel strongly that temperature must be a part of any cell testing or otherwise the tests can't be used to compare cells. These tests are my first step in trying to get a handle on how we can give these cells true CDR's. Based not only on capacity and voltage-under-load but also based on how safe they are to use at different discharge current levels.

    Manufacturers rate their cells for use at temperatures up to 60°C, maximum. At temperatures exceeding about 45°C a cell's aging accelerates, shortening its life. At 70°C-80°C a cell starts increasing its self-heating due to additional exothermic chemical reactions. If this self-heating is not stopped, or the heat pulled away by cooling, it will eventually lead to venting, bursting, and possibly thermal runaway. At approximately 120°C an important component in a cell starts melting (the separator), leading to short-circuiting and more self-heating. This is a point where the cell starts to be in big, big trouble. And so is anyone using that cell.

    Different chemistries have different temperature thresholds for thermal runaway but all suffer similarly at temperatures below this (accelerated aging, exothermic reactions creating gas and increased internal pressure, separator melting, etc) which can lead to venting and/or bursting. It's why I did not differentiate between the chemistries when setting the maximum temperature I would let a cell reach before stopping a test.

    Testing ICR cells (LiCoO2, "lithium-cobalt-oxide", "LCO") is riskier than testing the IMR (LiMn2O4, "lithium-manganese-oxide", "LMO") cells we normally recommend for use in a vaping device. This is due to the lower thermal runaway temperature of lithium-cobalt. It makes measuring of the cell temperature during a discharge all the more important.

    I have set a safety limit of 100°C for all of my tests, which is a ridiculously high temperature to operate a cell at! But I know that vapers will always want to reduce device size by reducing the number of cells so we'll go as hot as we can without getting too close to thermal runaway. Know that operating at over about 45°C reduces cell life though. If the cell exceeds 100°C before completing a discharge at its continuous discharge rating (CDR), then the cell is definitely overrated. It's just to dangerous to use continuously at that discharge current level. Under certain circumstances I'll let the discharge continue even if the cell temperature is above 100°C. But this is guaranteed to damage the cell and might lead to venting or thermal runaway.

    For reasonable cell life, I have set a limit of 75°C. While this is high enough to speed up the aging of the cell, it will still allow using the cell for a reasonable amount of time before needing to replace it. Beware of using any cell at higher temperatures than this. Not only can the damage become quite severe very quickly but it also takes you closer to the temperature at which the cell could vent.

    I realize that vaping does not discharge the cell continuously and that it will run cooler when used in a device, even if each time the device is fired it draws current equal to the cell's CDR. But we must have a safety margin when using these cells! If a device autofires then knowing that the cell you have picked will not vent, or worse, is very important. And a cell that is short-circuited might not destroy itself, and your device, if we can pick the one that runs cooler at high discharge current levels. This can only be done if we know how hot these cells get.

    I would love to see the ECF community come together to create a set of standardized test requirements to use when comparing cells and determining their safety at different discharge current levels. Using these tests we could set an accurate and safe current limit for each cell. Not just for continuous current, but also for "pulse" current testing that better simulates what happens when cells are actually used in a device. Additional tests could include cell leakage rate (good for estimating degree of damage to a cell), internal resistance, total joules delivered for each discharge current level (not a test, just some math), and cycle life testing.