Hi All, I thought that I'd throw some light on this as I know LOADS of people who have had trouble with the 3DAM mount not charging. Here is the reason.
Firstly, you should know that there are two versions of the mount, one for the XT and one for the XT2. The reason is that the XT runs on 5v (a voltage regulator is in the factory cable) and the XT2 runs on 12v so can be powered directly from the bike.
The problem with the XT version is that the voltage regulator that they fit inside the mount (MP4560DN) drops the voltage to 5v ok, but it doesn't allow enough current draw to actually charge the Zumo for a sustained period. I know this because I pulled it apart and put a meter on it (see attached 1). This means that the Zumo gets enough power to tell it to turn on and just about enough to slow the rate that the internal battery discharges a bit, but not enough to reliably charge it. Eventually, depending on what current draw the Zumo is using (screen brightness etc) the internal battery depletes and it shuts off. Also, depending on current draw and temperature, the voltage regulator (which has no heatsink on it) overheats and shuts down for thermal protection. It may then come back on again for a while, but it'll never run reliably all day with the screen on full brightness and everything on (Bluetooth etc).
They may have updated the module now, but in the version I have (one year old) it's a design flaw. 3DAM should replace them but their customer service is pretty bad and they’ll fob you off back to the dealer if they can or tell you it’s a problem with your BMW mount.
Which brings me on to the second point. An XT2 will fit in the XT adapter, but obviously won't charge properly because it wants 12v and is only getting 5v (and at low amps). If you have a XT mount and want to use it for an XT2, you can simply mod it by removing the voltage regulator board like I have (see attached 2). Just remember not to put an XT on there after the mod; Garmin may have put a voltage regulator chip in the XT just in case someone wires it in direct to 12v (would seem sensible) but I’m not smoking one just to find out!
HTH.
PS, just to show you how far out of spec that chip is, you can see on the
Garmin website that the XT draws 7.5 watts (5v x 1.5 amps). The max output of that voltage regulator according to the
manufacturer's website is 2.5 watts, so little wonder it overheats!