I have GPSMAP 62sc latest firmware and when i connect to PC it goes to flash drive mode and with USB logo appears on device screen.
Made some research and noticed that unit has no way to power on or charge from USB cable using wall AC adapter, car charger or computer, there is specially wired USB cables on sale to enable this, but if you have no such cable you might try this.
Here's how you can use it without battery with USB cable, i only tried on windows based PC running Windows 7 64bit.
1. Connect unit to PC and a new virtual drive appears under "My Computer".
2. Using VMware Virtual PC Workstation software (free VMware player might work too) [Only registered and activated users can see links. ], boot guest OS and selected from main menu VM > Removable Devices > Garmin USB Mass Storage Device > Connect
3. Now it will try to connect it might succeed and you see new virtual drive in guest OS or it might report error, it does not matter next step will work in either way.
4. Now again go to main menu VM > Removable Devices > Garmin USB Mass Storage Device > Disconnect
5. Unit now disconnected from guest OS, but instead of new virtual drive appearing in your main OS - unit just powers on normally and works. Even without batteries.
At least if you in the truck or car you can power your laptop or handheld from charger and use unit that way if your battery died.
EDIT: Now my unit started to power on into normal mode at step 3 so keep eye on device when you go trough steps.
Last edited by 555; 21st June 2014 at 02:24 AM.