On Wednesday, April 9, 2014 6:33:34 AM UTC+12, Paul Remde wrote:

Nothing. The Nano's battery compartment is separate from the sealed GPS

engine and logger section. Anyone can change the battery without affecting

the security seal.

I'd also add that the nano seems to work fine with no internal battery, just using external power. It retains the settings and the seal without any battery in the battery compartment. I've been using it daily with no battery for over a week with no problems.

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Philip Plane