The Activ Energy AA cells tested were 2400 mAh capacity, low self-discharge and “extra long life”. Here is a comparison with Eneloop specifications:
|Activ Energy AA cells compared to Eneloops. Minimum rated capacity reported. The standard eneloops I own and measured. The Panasonic Eneloop Pro dimensions and mass are from lygte-info.dk|
The mass of the Activ Energy AA cell is about the same as for 1900 mAh Eneloops and lower than 2450 mAh Eneloop Pros. The capacity of the Activ Energy cells appears over rated in this comparison.
Maximum cycles was not specified for the Activ Energy AA cells. I assume maximum cycles is about 500, like Chinese Eneloops
Self-discharge performance was not specified for the Activ Energy AA cells. I assume 85% capacity retention in one year, like the Eneloop Pros and 2nd generation Eneloops.
The Activ Energy packaging included an LGA tested quality mark. It was not explained what product features were tested.
I don’t have a battery tester. I discharged the cells using a 2.4 ohm resistor and recorded voltage and current at regular intervals. Discharge current was about 400 mA and discharge duration was about 5 hours. I stopped the discharge when voltage decreased below 0.9 V under load. Estimates of capacity are imprecise because of low sampling frequency and variable end-points.
I charged the cells with an Olympus Ni-MH Battery Charger BU-100 (around 2002 or 2003 vintage) at 490 mA per cell.
The Activ Energy cells were tested in the following sequence:
- Initial charge (top-up).
- Discharge 1.
- Discharge 2.
- Recharge and one week rest.
- Discharge 3.
For comparison, I also tested one new Panasonic Eneloop and one well-used Sanyo Eneloop:
|Discharge capacities. Four Active Energy cells were discharged three times. One Sanyo Eneloop and one Panasonic Eneloop were tested one time.|
Average discharge capacity for Activ Energy cells was similar to Eneloops. Other tests of Activ Energy cells have reported mean capacities of 2045 mAh after a few break-in cycles (previous generation, 2300 mAh cells) and 2220 mA. Altogether, these tests show 200 to 500 mA less than rated capacity.
The Activ Energy cells had flat discharge curves and mid-discharge voltage was close to nominal 1.20 V for NiMH cells.
Activ Energy cell voltages initially were 1.29 V at 12 months after manufacture. This was not far below freshly charged 1.42 V and well above nominal 1.20 V. Although I did not measure initial capacities, these voltage measurements strongly indicate that the Activ Energy cells are low self-discharge cells.
Referring to the previous section, discharge capacity after one week of rest was 3% lower than the preceding test. Another test of Activ Energy cells reported 3% capacity loss in 5 days and 8% capacity loss in one month. The self-discharge rate declines over time and maybe these Activ Energy cells can retain 80% of their capacity after one year.
In four-cell packs, Activ Energy AA cells (AUD 1.75 per cell) cost less than the Australian retail price of Chinese Eneloop AA cells (about AUD 5.00 per cell). However, I am not confident about cycle life for either of these products. I would choose Activ Energy cells if I urgently needed to buy NiMH cells. I would choose Activ Energy cells over Chinese Eneloops if cycle life was similar. The best choice remains quality Japanese Eneloops.