7" GPS Windscreen Mounted Sun Protection

It works fine, just concern that the unit gets mighty hot.

As do the more expensive Garmins. But the fact that they do "operate OK" is separate to the short internal battery life from the sun beating on the back of the case (matt black, inevitably, for reflection reasons). And I'm sure Garmins aren't the only ones to suffer this.

If the GPS is ONLY ever going to be used in the vehicle, maybe independent battery life doesn't matter. My first Garmin Nuvi (late 2008) has spent only nine months on the road, and the original unplugged battery endurance has dropped to about FIVE SECONDS. Yes, the thirty second shutdown after power-off gets to 25 seconds and "battery low" comes up. Our later Nuvi has a "sunshade" made from cardboard and the internal temperature would be a heap lower. Can't hurt.

And before people start saying "batteries don't last that long anyway", I have an early Li-Ion laptop battery dated 1997 that still delivers over an hour's run-time. There's more degradation due to elevated temperature than cycling in these batteries.

I stupidly left a tranny on the dash once and it turned into a plastic mess. Not a bad idea to cover it with something to stop the direct sun when the car is parked in the sun.