I store my lights with batteries in them as you do. I occasionally have a battery go bad and it does destroy the light. It's a risk I am willing to take for the convenience of not having to bother with assembling the light / battery when needed. Unfortunately a dead battery is cheaper than a dead flashlight. I have considered storing the batteries in the lights with some protection. One light that I bought for the car kits came with a little plastic disk that kept the batteries from connecting while stored. This was a great thing and I left it in-place. This means that I will have to dissasemble the light and remove that disk before I can use the light. It also means that the light won't run down the battery without me by accident. Some ideas that I have seen use include saram wrap the battery inside the light when in storage thus protecting both the battery and the light, Using ranger bands or similar to hold the batery to the outside of the light while in storage. Having a dedicated battery box with every imaginable backup battery, a charger, and a variable output power source with a deep-cycle marine battery in the truck - This one I use.