rg12 said:
I don't understand the chart, what are the other IR numbers on the other columns?
DCIR IEC is a standardized "two stage method" of measuring DCIR, which requires slightly better equipment to perform, DCIR 10s is "single stage" method, which is very easy to perform, you have to just measure the voltage in 10th second of applying defined load current. Measuring of DCIR is tricky, because there is no "true" absolute DCIR value usable for all cases, so the common approach is to choose method, which is close to your mode of operation and then just compare the cells side by side. You can see in this table, that those two methods are mostly only shifted.
rg12 said:
I don't get it, how come 30Q and 25R have the same IR but one is rated for 8C and one for 5C?
My opinion is that Samsung do this because cycle life of 30Q, ale least from initial production batch sucks.
rg12 said:
Also, how come you say that 40T is good according to this chart while it goes bad really fast?
If you perform "a lot" of your own measurements, you find out that there are to little generalization rules to follow when evaluating li-ion cells. In fact most of informations about cell life which you find on internet are only "old wives' advice" based on rules which actually did not works in significant amount of cases :?
Many people forget when evaluating cell EOL, that there are two major conditions. Capacity fade and DCIR rise, where the DCIR rise is important particularly in applications with more than 0.2C (rated capacity) discharge load. Also there is of course no general rule about dependency between this two parameters. So you can find many cells with high capacity fade but with relative stable DCIR and also cells with relative low capacity drop but significant DCIR rise, which make some cell almost unusable just at ca 85% of remaining capacity.
By the way he asked for 8C discharge cell and 40T can do this, I am thinking that nobody sensible will expect that 40T or similar cell design can do much more than 250 cycles under this continuous load or the discharge end cell temperature will be significantly lower than 80°C.