They reach max temp at lowest voltage. Running them down to 2.5 volts is fine for determining generic specs when application is unknown. Since he's doing these tests for the vaping community, his testing parameters are flawed. For our purposes a vtc5 is a 30amp cell.
Thanks for your feedback! I feel my test results are directly applicable to vaping.
Every single vaper, new or experienced, uses the continuous discharge rating (CDR) when initially determining if a battery is worth a closer look or purchase. All of us. It's the only way we can compare one battery to another as "pulse" ratings are useless without knowing a lot of info about the pulses, the criteria used to set the rating, etc. The CDR is a standard method of comparing batteries for a good reason, it's done fairly consistently across the big manufacturers.
Determining the CDR is also critical for determining which cell might be the one being rewrapped by the various companies doing that.
The CDR is also a very handy number to have when recommending limits for new vapers.
Lastly, extending the continuous current testing beyond the CDR allows me to determine when a battery might become dangerously hot if there is a mod malfunction or accidental button press (my Maximum Vaping Amps, MVA, rating). This is an important limit for a lot of vapers taking their first step into higher power vaping or unregulated/mechanical mod use.
I measure the temperature of the battery during discharge because it's the only way you can set the CDR (as temperature is the primary determinant of cycle life) and to set safety limits. A rating set without knowing the temperature is useless.
Any vaper is free to vape at current levels higher than the MVA rating, of course. They're not set as a limit for safety or performance. They're set as a way to directly compare one battery against another to determine which might be the best for the way we vape. Some vapers can, of course, use them as safety limits if desired.
We don't need to exactly duplicate the way each vaper uses batteries in order to pick the right one. The relative performance of these batteries changes very little if you compare them when running continuously or when pulsed. Which makes sense. Any discharge over a few milliseconds long is "seen" by the battery as just being a continuous discharge of a different length, whether 3 seconds or 33 minutes.
IMHO, the testing parameters I set for determining the continuous current rating, modeled after those used by Samsung, Sony, LG, and Panasonic/Sanyo, are well chosen for determining the continuous current rating of a battery. What parameters do you feel should be changed?
Or do you mean my feelings that vapers would find the numbers useful is flawed?
To help those who wish to go beyond the CDR and/or MVA rating I do pulse discharges for almost every battery. These go up to 70A if the battery can handle it without dropping below 2.5V immediately. Up to 80A for incredible performers like the A123 26650. This is about a 0.04 ohm total resistance, from the battery out to the coil and back again, simulating a 0.02 ohm or lower coil resistance once contact/mod/atty/connection resistances are taken into account. This would seem to cover just about any vaper out there.
These pulse discharges can be used to directly compare run time, voltage under load (i.e., how hard it hits), and maximum temperatures. None of the tests have to match the way any particular vaper uses them. The tests only have to make it easy to determine which is the best performer at certain discharge current levels.
Why down to 2.5V? It allows for easy comparison between batteries at higher voltages and it helps to show that batteries sag much, much more than people think. Cutting off the discharges at 3.2V or 3.5V (or wherever) wouldn't add any new data and would keep us seeing the true sag in unregulated/mech mods.
You can certainly just set your own cutoff voltage and see how each battery performs down to that point in the graphs.
Why only measure max temperature? I could certainly post plots of the temperatures of each cell during each discharge but most vapers don't need to know the temperature at a certain point, just which battery runs cooler/hotter, i.e., their relative performance. It's already quite confusing for many vapers just to understand the voltages shown in the pulse plots. Having them also have to read the temperature graphs would cause a lot more confusion.
I use constant-current pulses because that discharge method is in between the two methods we use to discharge batteries when vaping; constant-resistance and constant-power.
Constant-resistance discharging simulates what happens when we use an unregulated/mech mod. As the battery voltage drops the current through the (relatively) fixed-resistance coil also drops. This is the discharge method that is easiest on the battery.
Constant-power discharging, used by regulated mods, increases the current through the battery as the voltage drops in order to keep the power being delivered steady. This is the discharge method hardest on the battery.
Constant-current discharging is the standard used for battery testing as it's easiest to specify and duplicate. I use it because it's in between the two methods we use when discharging a battery when vaping. Holding the current steady is tougher on the battery than what's done when using a mech but easier on the battery than when we use a regulated mod.
Doing both constant-resistance and constant-power discharge tests, at any discharge level or down to any voltage, wouldn't provide any better data. It would just take much, much longer to do the tests. The relative performance of the batteries wouldn't change.
You say the VTC5 is a 30A cell for our purposes. That's fair. I would probably say 35A due to its decent internal resistance keeping the temperatures and voltage sag average for a high performance 18650.
But those are statements of capability, not battery ratings. Ratings are set to help us choose batteries based on consistent, standardized testing that determine cycle life, safety limits, and (for my pulse tests) actual voltages-under-load. This is what my testing is for.
A battery's capabilities will change for each vaper and their vaping style. We can make some conservative statements that cover most vapers, i.e., VTC5's are a 30A cell, but my testing provides a known, consistent way to narrow down your choice of battery. The pulse discharge testing can help you narrow down your choices even more.
Some only need a general statement of capabilities to determine what battery to buy. Others might want to know that the VTC5A hits harder than the HB6 even though the HB6 has a higher current rating. Or what the safety limits might be in case of a mod malfunction or accidental button press. You can't determine that from capabilities statements, it takes the specific tests that I do.
My test results are there for those who either want to set some conservative safety limits or for those who want to know which battery will actually give them the best performance, i.e., which will give them the highest voltage, longest running time, and/or lowest temperature during use.
I am genuinely interested in hearing what testing parameters you would use, ones you feel would not be flawed. I'm always open to improving my testing.
