Guys: I've argued for two years now that the D cell batteries with an expiration date 7 years out didn't need to be changed every two years. I argued the only reason it was common place is that what we got used to with the earlier ELTs. Well, I take it all back, I was wrong, and I'm not sure they should go two years. Let me explain, I am in the process of doing my 2nd condition inspection on my RV-9A, it will be two years old next month and has 315 hours on airframe and engine. Today I removed the AmeriKing ELT to change the 6 D cell batteries. I found that one of the six had leaked acid into the battery case and that all six had a voltage of 1.47v. The new batteries had a voltage of 1.62. I brought the old batteries home and put them into my 3 cell flashlight and the bulb was not as bright as it was with new batteries. The old batteries are the Duracell Alkaline Battery, MN1300, LR20, and 1.5v with a Mar 2014 date. I wonder if I should routinely change the batteries every year or find another brand of battery that will not leak and will hold the voltage for at least two years. What do ya'll think? Dan.