Just ordered an XL*S from Costco ($249) but haven't received it yet. Was looking at the expected battery life and rather dismayed by the 2 hour estimate. Wondering if there is a Lithium Polymer replacement available. Also wondering about how easy the unit is to disconnect from the windshield. I travel quite a bit and use rental cars so being able to mount and dismount the unit quickly is an issue. Thanks for any assistance.