Proposed testing procedure is as follows, designed to produce reasonably
relevant results for real-world uses such as digital cameras.
New cells only: Discharge at 0.2C to determine maximum off-the-shelf
capacity (for Eneloop cells) and prepare all cells for breaking in.
The 0.2C rate is used here because it will provide a direct comparison
with the 0.2C discharge used in the break in (step 3).
Used cells only: Fast charge (0.5C rounded up to nearest 100mA), then
discharge at 0.2C to determine initial condition.
Both new and used cells are broken in (or "formed"), using
the claimed capacity entered into the MH-C9000 for it to determine charge
and discharge rates. As per the MH-C9000 regime (from an IEC specification,
apparently), cells are charged at 0.1C for 16 hours, rested for one
hour, discharged at 0.2C, rested for one hour, charged at 0.1C for another
Rest then discharge AA cells at 1 amp, AAA cells at 400mA.
Fast charge (0.5C rounded up to nearest 100mA), rest, then discharge
at 1 amp (AA) or 400mA (AAA).
For Eneloop AA cells: Charge at 2 amp for 1.1 hour, rest, discharge
at 1 amp.
For Eneloop AAA cells: Charge at 800mA for 1.1 hour, rest, discharge
All charge and discharge rates are nominal; the MH-C9000 integrates the
total mAh based on the actual current. It terminates discharge at 0.90V,
avoiding a possibly damaging deep discharge. 500mA is the analyser's default
discharge rate but at present it seems like too much work to include it
in the test regime, and it's the same as the 0.2C test for 2500mAh cells
anyway. 1 amp is a very common discharge test, since digital cameras often
use about that much current.
Resting the cells after charging gives more realistic capacities than
using them "hot off the charger".
All testing done at room temperature, whatever that may have been at the time.
Break-in Start/Finish Completion Times Chart
The whole break in process takes at least 39 hours - more than a day
and a half. See the table below for start and finish times.
Light grey for the day after commencing, darker grey for the day after