Ah - a chance to rag on TomTom.
I bought a TomTom Go730 some time ago before I bought my 2013 Trail with Navi. 730 was last made in 2010 after Microsoft sued so they could not use FAT32, they switched to all Linux.
I had bought several TomTom map updates along the way. The last one I bought, in say July 2013, the last update was in May 2014. After loading that, the map was too big to install into internal memory. So I followed instructions and installed to a 4G SD card. After that, the touch screen no longer works. After following some notes on somebody's post on a GPS site, I was able to get the touch screen working, but then once I install the map, again, no touch. Worst of it is, I didn't find until too late, I was supposed to back it up NOT using their software - the backup I have is of something that was no good (didn't follow instructions, my bad).
So now I have a lump.
I am going to try one more time, but I am royally pissed at them, sell me a map knowing full well its going to screw up my unit. This elephant won't forget.
So, any brand other than TomTom.
I had come across some Android App that allows downloading of maps. Make sure to do it with WiFi on. That would be my vote.
Remember anything with a battery, the battery is only going to last so long. GPS, cell phone, car, cordless drill. At least cars you can easily get a new battery.