I am discharging a few cells to see how they preform and thought some of you guys might be interested. Im sure there are better was to test but this is how i have quickly set it up. My Fluke meters are calibrated by an external company (Pullman instruments), these give a accurate idea whats actually being drawn from the cell.
Ok just to explain what the pictures show. The Fluke 179 on the right is wired in series with the cell and charger, so what ever current goes through the cell goes through the meter, this shows that the hobby charger is actually discharging at the correct rate as they are far from accurate in some cases.
The Fluke 123 on the left is displaying the voltage across the cell, this again shows how accurate or not the charger is. In this case it shows that infact the cells are being terminated early so the capacity reading will be lower than could be expected should you discharge further, ie 2.7volts.
If the two figures are multiplied then the result is the power consumed, eg 3.8v X 1a = 3.8watts.
The other variable for my charger will be the timer itself so perhaps I will stick a stop-watch next to the counter and ensure that is accurate. Edit:Tested to within 2seconds at 2hours.
Please only compare my results within themselves, my methods mean that lower readings will be obtained compared to other people's. Within themselves these results should be very accurate and representable of performance.
Little table with Impedance readings and some random calculations i was interested to compare:
Why Impedance is important: The output capability is determined by the Impedance if nothing else limits the cell, ie in a direct drive light, lower impedance = more current and more output (or a blown emitter). Impedance also steadily increases with age and gives a good ability to trend and thus monitor ageing. Impedance matching is also more useful than voltage matching cells for multi-cell set-ups, it tends to give far more accurate results, tho DC matching is still essential.
King Kong 26650 - 4031
Panasonic NCR18650A 3100mAh - 2609>2619
Sanyo 2600 - 2256>2339
SenyBor SYB18700 2600mAh - 2219
SoShine 2800mAh - 2095
TrustFire Flame 2400mAh - 1817
UltraFire 'blue' 2400mAh - 913
Trustfire flame 14500 900mAh - 640 (1a)
TrustFire tr 10440 600mAh - 243 (0.5a discharge)
Ultrafire (silver) 14500 900mAh - 124 (1a)
Anyway, SenyBor first:
Please comment if these are usful and i will add some more as i do them (Trustfire Flame discharging at present)