2 aa vs 3 aaa

dougw

Newly Enlightened
Joined
May 8, 2010
Messages
33
Which set up has the most available energy? ie if they are running the same emitter and control circuitry, which would last longer?
 

AnAppleSnail

Flashlight Enthusiast
Joined
Aug 21, 2009
Messages
4,200
Location
South Hill, VA
Your post is in LED. 3 AAA could direct-drive an emitter, so it would tail off towards zero output over infinite time. 2 AA requires a boost driver, which will have a particular efficiency and a minimum functional voltage.

AAs usually have 2 Amp hours, while AAAs usually get about 800 mAh. A pair of AAs has 2 times voltage times capacity - for eneloops, 2*1.45v*2 Ah = 5.8 watt-hours. This is approximate, as the voltage will drop slightly towards the end of battery life. 3 eneloops AAAs would have 3 * 1.45v * .8 Ah = 3.48 watt-hours.

You'll get more photon-hours at a reasonable level from 2 AAs, but 3 AAAs will still weakly light for a long time.
 
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