That is a novel idea but the problem with the cheap units is that they work on triangulation of cell phone towers. This is not very accurate, as opposed to GPS positioning (within a few meters).
Forgive any grammatical/spelling/logical errors as I've drafted this out before finding my bed.
I would not do any purchase of a unit if it does not have GPS; some advertise as such (plenty of those on eBay) but do not have a GPS chip at all, using cell phone towers for triangulation. At least you know where it is, within a Km radius +/- a few hundred meters, since to do that it would need mobile SIM capability and possibly can send location data to you. Handy if it is in the bush but not so much once it gets into the suburbs (by which time it would have been found and promptly disposed of).
Problem two however is where they do not use a mobile sim card at all (ie, no means to transmit GPS co ordinates to a remote device) operate either using blue tooth (out of luck if the device gets out of range of your phone paired to it) or worse still with mesh networks (battery drain looking for the phone and/or another device to transmit to), which is pointless when the devices nearest neighbor is over 10 Km away (out of range).
Another problem with the cheap units is longevity. Battery life is uncomfortably short when idling and shorter still when you actively connect to the device (where it is capable of transmitting its location) as polling GPS/mobile reception towers uses energy to generate location data prior to transmission (again more power use, presuming it has that functionality).
I looked at similar devices to get cheap GPS car tracking before settling on attaching an older model smartphone to a vehicle. Tracking is simple with Google providing Android Device Manager (Find my phone), Samsung devices have a similar program or even third party apps like Prey. Phone tracking, especially where GPS is in the phone, is ideal and a proven technology and it does not need to be the latest and greatest to do the job (some of you reading this post probably have a spare smart phone lying around that would work for car tracking).
Battery life is good and better still if you can wire it up a vehicle, but be careful with placement of the phone because of the battery, same reason to avoid battery powered car dash cameras in favor of the super-capacitor units. Just be careful what SIM card plan you use, preferably prepaid with no excess data costs (no bill shock) and online recharge so the phone stays undisturbed. Check intermittently that it is still tracking/working correctly so you can fix any issues before Murphy pays you a visit (Murphy's Law).
Phone (or similar device) should IMO have at least 3G on any device you use; Telstra 2G is being shut down Dec 1 2016 so mind that when looking at the cheap car/boat/caravan units on eBay or those TK units that cost a bit more than an older smart phone (nothing about them screams avoid to me, pending 2G v 3G/4G, but I had the spare phone lying around so saved a little coin
).
Not sure what I would use on a GPX/Zed (opening the box = goodbye warranty, don't do that) as there are not too many places to hide a phone. A phone in a protective cover would be a short term solution, but someone stealing one of these is clever enough to know about phone tracking, IMEI device tracking and other tricks of the trade will either attempt to flash the phone quickly, remove the battery or simply leave it in your car/campsite so your not instantly aware of being burgled to catch them in the act.
Otherwise it is finding a phone/similar device that fits the technical requirements and can be attached somewhere the untrained eye will not find it, just seems a waste to have the battery unit right there and not be able to leech off it between recharge and outings for that extra peace of mind.
I'm hoping posting the above however will get some peoples grey matter going so I can benefit in protecting my investment (paid more for it than I did my car actually :8 ); or Minelab catch on and add an accessory and/or something inside the box for future models and savings on recovering lost stock.
Now I believe I was off to bed...
