SporkSports - NiMH Battery and Charger Review -- February 2008

(5-31-08)

Condensed notes on the battery testing:

Last updated: February 6th, 2008

What follows is a condensed version of the data collected from my battery testing. The charger used is a Maha Powerex C-9000 battery charger. The primary real-world discharge device is a Garmin GPSmap 76S rated at 16 hours battery life in battery saver mode on alkalines.

My current battery inventory is as follows:

Brand Model Capacity Quantity

Sanyo Eneloop AA 2000 12

Powerex AA 2700 8

Energizer AA 2500 4

Sanyo Eneloop AAA 800 8

Powerex AAA 1000 4

My desired array of tests would be something like this:

Cycle each set of batteries at least 10 times to assure totally broken in
Test batteries in Maha C-9000 to determine reported capacity
Measure capacity in near-freezing temperatures
Determine lifespan of various cells in GPS both in and outdoors if needed

So here's the data so far. More to come as the testing continues.

Garmin GPSmap 76S discharge testing

Battery Test condition Duration

Energizer 2500 Normal run, 50 degrees overnight 14:03

Powerex 2700 Normal run, 50 degrees overnight 16:59

Powerex 2700 Full backlight, 35 degrees overnight 9:49

Powerex 2700 Battery saver mode, 65 degrees when dead 22:07

Eneloop 2000 Normal run, indoors @ window ~55 degrees 13:35

Eneloop 2000 Full backlight, indoors @ window ~65 degrees 7:39

Discharge test from newly delivered cells

Battery Rating Discharge Rate Avg Capacity Percent of rated

Powerex AA #5 - #8 2700 mAh 200 mA 174 6.4%

Eneloop AA #1 - #4 2000 mAh 200 mA 1346 67.3%

Eneloop AA #5 - #8 2000 mAh 200 mA 1362 68.1%

Eneloop AA #9 - #12 2000 mAh 200 mA 1373 68.7%

Eneloop AAA #5 - #8 800 mAh 100 mA 585 73.2%

Break-in charge reported capacity

Battery Rating Capacity Percent of rated

Powerex AA #5 - #8 2700 mAh 2585 95.7%

Eneloop AA #1 - #4 2000 mAh 1946 97.3%

Eneloop AA #5 - #8 2000 mAh 1996 99.8%

Eneloop AA #9 - #12 2000 mAh 1935 96.7%

Eneloop AAA #5 - #8 800 mAh 805 100.6%

200mA 37 degree discharge test

Battery Rating Capacity Percent of rated

Powerex AA #5 - #8 2700 mAh 2333 86.4%

Brand	Model	Capacity	Quantity
Sanyo Eneloop	AA	2000	12
Powerex	AA	2700	8
Energizer	AA	2500	4
Sanyo Eneloop	AAA	800	8
Powerex	AAA	1000	4

Garmin GPSmap 76S discharge testing
Battery	Test condition	Duration
Energizer 2500	Normal run, 50 degrees overnight	14:03
Powerex 2700	Normal run, 50 degrees overnight	16:59
Powerex 2700	Full backlight, 35 degrees overnight	9:49
Powerex 2700	Battery saver mode, 65 degrees when dead	22:07
Eneloop 2000	Normal run, indoors @ window ~55 degrees	13:35
Eneloop 2000	Full backlight, indoors @ window ~65 degrees	7:39

Discharge test from newly delivered cells
Battery	Rating	Discharge Rate	Avg Capacity	Percent of rated
Powerex AA #5 - #8	2700 mAh	200 mA	174	6.4%
Eneloop AA #1 - #4	2000 mAh	200 mA	1346	67.3%
Eneloop AA #5 - #8	2000 mAh	200 mA	1362	68.1%
Eneloop AA #9 - #12	2000 mAh	200 mA	1373	68.7%
Eneloop AAA #5 - #8	800 mAh	100 mA	585	73.2%

Break-in charge reported capacity
Battery	Rating	Capacity	Percent of rated
Powerex AA #5 - #8	2700 mAh	2585	95.7%
Eneloop AA #1 - #4	2000 mAh	1946	97.3%
Eneloop AA #5 - #8	2000 mAh	1996	99.8%
Eneloop AA #9 - #12	2000 mAh	1935	96.7%
Eneloop AAA #5 - #8	800 mAh	805	100.6%

200mA 37 degree discharge test
Battery	Rating	Capacity	Percent of rated
Powerex AA #5 - #8	2700 mAh	2333	86.4%