Do you have a 511 or 551? I have nothing concrete to back this up, but I have heard that heat has negative effects on the N type batteries. I know some people who were having some issues, some of which seemed to be heat related. They have since switched to 552's and the AA batteries seem to handle heat much better. I dont know any of this for sure, it is all second hand info...

Like I said, this is all second hand info... so I am only passing along what I heard, I cant confirm it at all. But the problems I have been told about were when the guns were stored in the trunks of police cars. It get a lot hotter in there than in the desert sun. I dont want to say for certain, but I think what I heard was temps above 150 or something can cause N batteries problems. Guns would be deployed from where they had been sitting in hot cars since the last time they were taken out. Sites did not work right out of the trunk. After they were out for a while and the EoTech had a chance to cool, they would work again.

If this is in fact the case, it isnt a problems with EoTechs, its a problem with N type batteries. I have no idea if this is at all related, but Surefire batteries will "shut down" too when they get too how. Its happened to me a few times with Surefires.

Anyway, Im just saying if he has a N model EoTech that will be exposed to high temps, there is a possibility that he may encounter the same issues. Heat from blast etc is a lot hotter than heat from the sun in the desert.