Garmin Edge 305 shuts off from vibrations during normal use.

Hello,

Try resetting the unit by pressing the "Mode"(reset/lap) and "Power" buttons at the same time.
Also, be sure that the unit has the latest update.
Reloading the latest update will resolve most issues.
download the latest version of WebUpdater software

Could be yes. There are contacts inside the device that become sensitive to vibrations after a while.

I have seen on Internet that it may also be due to USB plug that acts on these contacts.
Anyway in this situation there is no other way than opening the devices and soldering contacts or adding wires to replace these contacts.

As opening device is not at all easy, I recommend you send your device to Garmin support.

Otherwise please check the relevant procedure on the internet

Probably a bad contact inside then.

Be careful however to update the device and hard reset it once again before trying opening it.

If device under warranty please send back to Garmin, if you open oit warranty will end automatically.

If none of this is possible then try trick posted at following site :
http://blog.mtbguru.com/2008/11/06/surgery-on-the-garmin-edge-305/

It is a contact problem inside the device, Details of how to fix at following link

http://blog.mtbguru.com/2008/11/06/surgery-on-the-garmin-edge-305/

This is internal problem due to contacts that are getting dirty or spaced because of too much pressure on the USB port.

Better way is to unmount the device and solder wires in place of gold contacts.

Unmounting device is not easy, see following link

http://blog.mtbguru.com/2008/11/06/surgery-on-the-garmin-edge-305/

It is a connection problem inside the device. If it is under warranty you should send back to garmin, otherwise you can apply trick as described at following site :

http://blog.mtbguru.com/2008/11/06/surgery-on-the-garmin-edge-305/

This is a generic problem with the 205 and the 305 go to MTBGurublog and look up 305 problems there is a blog that shows how to open and fix it

The above link no longer works.
But this one does (for now): http://blog.mtbguru.com/2008/11/06/surgery-on-the-garmin-edge-305/

I made this surgery and it now works great.

I have the same problem. When I contacted Garmin they quickly diagnosed that my battery disconnects as a result of vibrations (like the ones you feel on your handlebars). Since I purchased this device over a year ago, their solution was for me to send it to them and pay $100 to get it fixed. Now one of the guys I ride with is having the same problem. I am very disatisfied with the Garmin 305's reliability. I'm not giving Garmin any more cash. (I paid $350 for this GPS 18 months ago!)

Does anyone know how to open the 305 so I can resecure the battery?

I moved the battery wires to the main board, bypassing the spring contacts. No doubt my warranty is voided but at least the thing works now.