Was talking to @Bear about Eneloop batteries and the adaptor sleeve for C & D size batteries. We were looking at these 3 AA parallel D size adaptors. I have been using the single AA Envelop D adaptor in my lantern for years. We take it camping and I typically change the batteries out about once a year. They have never died on me, so far. Some info... a typical D battery is about 8000 mAh and an Eneloop AA is about 2500. The Rayovac site says the lantern runtimes on 3 D batteries are 40 hours on high and 60 on low. So what I expect is for the lantern to run about 1/3 of those runtimes with the 3 AA's. So here's what it looks like with the 3 "fresh" AA's. I am not sure when they were last charged up, but suspect recently. The Rayovac lantern is a solid light. The 240 lumens is plenty in the dark. I set up the lantern for the test downstairs. And when the lights went out, I could see a very bright light spill upstairs from my bedroom. So while it isn't the brightest, it works for most things. Still going after 15 hours, so I call the hypothesis correct so far. The AA's make the lantern much lighter and it is easy to carry spares as well as a charger for camping, as I do. But truth be told, never needed them yet.