Sanyo Eneloops under a constant current 250mA discharge. Even under this load they hold over 1.25 per cell for hours.

Added 4-21-2010 .

There seems to be a fair amount of interest in te 250mAh rate discharge graph I posted. Bear in mind that a good non rechargeable AA is only aprox. 2000 mAh and since the normal life in an X-10 DS10A sensor is a year which is 8760 hours the average discharge rate(load) is therefore less than 0.228 mA. or 5.5 mAh per day.

One hour on the graph equals aprox. 45 days plus, Also consider that as the load rate is decreased the voltage under load increases.

To help make this a little clearer perhaps and as I have never done a lower discharge rate test I am now going to conduct a 100 mA(0.1A) CC discharge using two Eneloop AAs in series. These were last charged several days ago and at start of test were just over 2.6 volts for the pair.

I will provide updates latter.

Checked voltage of sanyo Eneloops in my Shop Door Sensor( (DS10A) and after 7 days they read 2.62 volts and there is a fair amount of traffic on that door.

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Here is a link to Energizer factory performance data

http://data.energizer.com/PDFs/E91.pdfOn page 2 note that at 250 mA at 21C the cell crossed the 1.2V point in four hours while my Eneloop graph at same 250 mA load still had 8 cells at 9.84 ( 1.23 per cell average)? after 5 hours. So much for thier (Energizer's) claim to great performance in high drain applications.

The two Enellops at 100 mA drain (current on going test) after 5-1/2 hours (550 mAh ) are still at 2.55 volts.

8 hours (800 mAh ) / 2.53 volts this is likely 5 to 6 months perhaps more of service life.

12 hours 1,200 mAh and 2.49 volts under load / 2.52 no load.

Attached graphs links below.

How two use A123 cell in DS10A (Door / Window Sensor)posted here

http://www.rcgroups.com/forums/showpost.php?p=14916113&postcount=1Worth a look IMO. 15 hours at 100 mA discharge rate and cell was above 3.2 volts.

Note to moderators. The above is a Hot Link but RC Groups has no problems with them and I am a long time / active member there.

I wonder if there would be any interest in a rechargable battery Thread?