Mag 3D with Nite Ize (0.5w) and 3 x AA batteries in adapters only good for about 12 hours! why??

I thought to give my maglite a try, that has been in my emergency backpack,

with 3 xAA (LSD Nimh 2000mAh) batteries in AA to D adapters.

I wanted to see how much runtime it would provide, and turned it on at 8PM, thinking it would still be good the next day at 8pm...... Wrong!

The next morning around 8AM it was okay.. but at around 11 am the light was soo weak, I could just look right into the bulb, without any problems.. it was really dim.

I hoped this NiteIze (0.5w) bulb would have a really really long runtime.. But now Im really doubting.
Maybe a Mod with a R5 or so, and a good Low would be better?

1. Why do you guys think this light didnt actually work longer than about 12 hours?batteries just empty?

2. Do you think that when I put in some energizer lithiums in it, they wont drain at all?

3. Is it better to store batteries only Outside the light, in stead of Inside (for draining)?

(I guess I wont be able to come back to this thread for a few days, switching Internet provider, and previous one will stop tomorrow, and the new provider hasnt hooked us up yet)

If you do the math, your three AAs contain about 7 watt-hours of energy (2.0 Ah * 1.2V * 3 = nominally 7.2 Wh), so if the dropin truly draws 0.5 watts, you'll get about 14 hours.

In real life, the dropin is probably sucking more than 0.5 watts to drive the LED at 0.5 watts, the batteries probably have less than 7.2 Wh of energy, and the dropin may not be able to extract all of the battery's energy anyway....

Hi Ralf, sorry for my late reply.. we have currently no internet at home.. some trouble with the providers..

thanks for explaining..
I honestly thought that this setup would last a lot longer.. I guess a D cell has a much higher capacity than AA cells..

Does anyone know by chance, how much mAh a regular D cell has? for example a D alkaline duracell..