I did want to add a bit to the conversation here...
I did the Aspire 1800mAh testing mentioned earlier.
My original testing of the Aspire 1800mAh battery was done to just generally compare the performance of a cell in a Keystone holder versus one in a low resistance test rig. I uploaded the Keystone holder results first, expecting to follow up about 12 hours later with the test rig tests...huge mistake. Everyone ran wild with the, as you would expect, lousy results for a cell discharged at high rates in a holder.
So I retracted that test, apologized for the confusion, and decided to start over with new cells. This is the second set of test results that look so much better. Why? Because the cells were in a low-resistance test rig. They actually tested quite well, equaling the VTC4 just in those tests. Would I ever recommend them as replacements for the VTC4? Never. The Aspire 1800's get damaged at above 30A a lot more than the VTC4's and they're ICR chemistry. They're not hand grenades waiting to go off but it is an additional risk that I feel is unnecessary with all the other choices out there.
For the record, Aspire's 40A rating of the 1800mAh cell was criminal. When testing I try to stay neutral and leave any thoughts about the actual performance versus the rating to others. The tests say a lot all on their own. Though that has been harder and harder to do with the preposterous ratings some cells are given. I'm very glad that for the 2500mAh cell that they went with a two-figure rating, 20A/40A. Though the pulse rating is useless, at least there is a continuous rating that I hope will prove to be accurate. Testing will begin on that cell soon.
My constant-current tests are not in any way to simulate what happens while vaping. They're meant as a basis for comparing one cell against another and against datasheet discharge curves from the Big 4 manufacturers; Samsung Sony, LG, and Panasonic. These discharges are used to establish a safe continuous discharge current rating based on max temperature and damage done to the cell over multiple discharges done at the max continuous rating. They set a limit for how hard you can run them but still not reach a dangerous temperature in case of a regulated mod autofiring or a mech mod having its button break, get stuck, or be accidentally pressed in a pocket. There is a 100°C limit for all ratings.
I do "shootouts" at various discharge current levels, directly comparing the performance of various cells at different constant and pulsed current discharges. The 4s on/30s off pulsed current tests are a decent approximation of how a majority of vapers...umm...vape. Well, at least according to the poll I posted at ECF. While there was a bit of shuffling of the top performing cells, the differences between performance in the constant current tests and the pulsed tests was only a few percent. There really isn't too much of a difference in the relative performance between cells for the two test types. I will continue to do these shootouts though because I think vapers can much more easily relate to and understand the pulsed current results. Though the graphs are much more crowded!
While plotting the temperature during a discharge can be done I feel it wouldn't add much to the already available data. The max temperatures I record for each discharge show the differences between the cells. The temperature increase during a discharge over time is quite linear and cell temperatures for various points along a discharge can be estimated, up to the point where the voltage nosedives. Most certainly not as easy as reading plotted temperature, but it can still be done. I do about a dozen discharges for each cell, along with recording max temperature, and a test report. That adds up quick and I just didn't feel that plotting temperatures and creating those graphs was worth the time for what it would add to the data. I realize that some folks feel quite differently than I do about this.
I'd be happy to answer any questions about my testing methods and results and look forward to becoming a part of the VU community. Thanks for your time in reading this!
