EGR - what do we need to tick off now?, page-40

As I think you are aware, one of the quirks of graphite is that battery testing takes time, a lot of time.

Testing how the battery performs over the first say 100 cycles is easy and fairly quick but the battery uses of stationary storage and EV's want knowledge about how long the battery will work, not that it should last a year or two. You want to know were the end-of-life period is. When will the graphite and other battery components mean the battery falls below 80% state of charge. How quickly does it degrade at the end of its life. The better the battery/graphite, the longer that testing will take. For instance, does the graphite and other battery components enable 2,000 cycles, 5,000 cycles, 10,000 cycles or more. If its more than 10,000 cycles is this just some of the batteries or all of them, and if >10k cycles, how much more? This would appear simple enough to test, you set up a system that charges and then discharges multiple batteries at the same time so you can see what variation there is across the sample of batteries being tested. The issue is that testing a large number of cycles takes a long time.

For example, if the battery were to be charged and discharged over a 1 hour cycle, you can physically only test 24 cycles per day. Running 24-7 you could test 8,760 cycle in a year. Unless you shorten the test cycle window below 1 hours, a test out to 15,000-20,000 cycles would take 2 years. You might know fairly quickly if you had a dud product, but knowing how good a good product is would take a long time. Note - I'm not sure how long the cycles would be in a test environment but they can't be super-short if its going to be representative of normal use.