Either use a quad lock and phone with airplane mode.
Or get a more modern garmin. 530 or 830. Tou can shift route across bluetooth from rwgps to the garmin. And the battery on those models will last 20 hours. 830 will allow you to pan around on the map as its thouch screen, 530 is buttons and wont.
Personally I'd be tempted by independent devices, then you've a backup.
How long are the ridea?
Either use a quad lock and phone with airplane mode.
Or get a more modern garmin. 530 or 830. Tou can shift route across bluetooth from rwgps to the garmin. And the battery on those models will last 20 hours. 830 will allow you to pan around on the map as its thouch screen, 530 is buttons and wont.
Personally I'd be tempted by independent devices, then you've a backup.