test6.x-series: This post is about discharge tests with my
Eagletac CR123A's
Here i am testing the Eagletac CR123A, a "3V 1500mAh" lithium cell, brand new, in my EBC-A device. Room temperature was close enough to 25°C, it was a sunny day outside. Problem: there is no PDF datasheet available, the official parameters are unknown which are to lead to the 1500mAh claim. What's the discharge rate (0.2C?), what's the cutoff voltage (can't be 2.50V because it's a lithium, not li-ion cell! did they use 1.50V or 0.80V as cutoff or anything else??), what's the temperature (prolly 25°C not 20°C)? Next question, is C to be taken as the rated/minimum capacity or the typical/nominal capacity?
No official or public answers/info is available, so i had to take my own sensible decisions.
I chose the following discharge parameters:
C = nominal capacity (since the min. capacity is unknown!) = 1500
standard discharge = 0.2C = 0.2*1500 = |-300mA|
cutoff voltage = 0.8V (that's the lowest possible on my device!)
Temperature = ~25°C
and i got the following result:
cutoff voltage@1.50V:
1400mAhcutoff voltage@0.80V: 1511mAh
Once the cell hit the 0.80V, i let it rest for some time and re-run the -300mA load to see if i could squeeze a few more mAh's from the "recovered" cell:
Interestingly, a CR123A cell doesn't auto-recover capacity like Alkaline cells do. Once it is fully discharged, it is dead and stays dead. The offline voltage apparently slowly recovers to say 2.60V but that's just "empty calories" so to speak.
The
accumulated capacities are:
1511mAh
1537mAh (after 1st rerun)
1546mAh (after 2nd rerun)
1553mAh (after 3rd rerun)
My point is, with measured 1511mAh i did hit the nominal capacity of "1500mAh". However, i had to discharge the cell down to inhumane 0.80V cutoff voltage. If i had stopped the test run at 1.50V cutoff voltage, i would have measured 1400mAh only! I am not familiar with CR123A primary cells, so i don't know what a reasonable or common choice for cutoff would be. 1.50V sounds like a good choice imo for various reasons, so next time I'll test in a similar way 0.5C discharge rate (=-750mA) when it's sunny and hot again in the test room
Stay tuned.