I have a PDW Dangerzone and a Planet Bike 2W Blaze that I run on Sanyo Eneloops. I charge the batteries up every Sunday night so there is no doubt in my mind whether or not I have good batteries for the commute week. My commute is during the day usually, but I run the lights in blink anyway because in urban environment, the lighting is always changing between light and shadow.
The amount of charge applied over the past few weeks has been fairly consistent. My AAA are charged with about 380-410 mAh for the PDW and the AAs for the PB Blaze get 330-350 mAh.
What I'm curious about is how my PDW is using more energy than my PB when it has two 0.5W LEDs and the PB has one 2W LED. Does this mean that the PDW is on more of the time during blink function compared to the PB?
PDW claims 50 hours run time, this seems very optimistic considering that the battery seems to be half-depleted after about 6 hours. The PB claim of 18 hours flash does seem realistic, and perhaps underrated since the batteries were only depleted by 1/5 after 6 hours.
Also please check the below calculation for cost to operate...I think it's right but need someone to do a look over.
Charge applied x voltage
1520mAh * 1.2V = 1.8 W*h
Cost of electricity
12 cents per kWh -> 0.012 cents per W*h
Charging a NiMH battery is about 67% efficient, and assume power adapter and charger are about the same so about 44% efficient.
Amount of energy needed to charge the set of batteries taking efficiency into account
1.8 W*h / 0.44 = 4.09 W*h
4.09 W*h x 0.012 cents / W*h = 0.049 cents
So for me to operate my lights is about 0.05 or 1/20 cents for electricity per week.