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Etrex 20 hangs during download of topo map to SD card

I wanted to use the Northcentral topo map (Idaho, etc) but it was too big to load onto my etrex 20. So I bought a 64 GB SD card, thinking I could have several maps. I am using the Garmin app on a Macbook Pro running 10.10.5. The download proceeded through the first file and on the second file the progress meter when from -40% to -10% to zero and then stopped. I have tried two separate network connections. I've been looking for documentation on loading maps onto SD cards but haven't found any. The Garmin manuals are rather terse. Does anyone know how to properly load maps onto the extrex 20 SD card? Does anyone know of the practical limit on the number of maps it can hold other than memory size?




  • sussamb 798 Points
    Your problem isn't due to memory size, pretty much every Garmin device, and certainly yours, requires cards to be formatted FAT32, which by default a 64Gb card isn't.
  • t923347 426 Points
    If your computer OS doesn't have an option to format a 64GB card to Fat32, do a Google search for Fat32 Formatter. There are a number of free programs that will allow you to format SD cards bigger than 32GB to Fat32.

    I've not used an Etrex 20 but another issue you may have even with a properly formatted 64GB card is that the device may not support a card that big. 32Gb maybe a safer choice.
  • Boyd 1974 Points
    edited June 2016
    Garmin maps consist of many smaller "tiles" or "segments". Your eTrex can only access about 3000 segments total. The total includes all maps you have installed in both internal memory and a card. It doesn't matter whether the maps are enabled, the 3000 segment limit applies to everything. If you exceed the limit, you will have problems with maps not displaying properly.

    There are no standard sizes for segments, they're determined by the mapmaker. But my point is, you will hit this segment limit long before you fill a 32gb card. Frankly, I think you will hit the limit in most cases with about 8gb of maps.

    With Garmin's 24k topo map series, I think you will find that you'll find yourself close to the segment limit immediately. IIRC, they typically contain 2000 segments. Anyway, you certainly don't need a 64gb card. 16gb will give you all the room you're likely to need.
  • sussamb 798 Points
    I've got about 10Gb of maps on my Etrex 20, so don't skimp on the card size should you decide not to reformat your 64Gb one. I wouldn't normally go smaller than 16Gb, but as Boyd points out your problem may be the tile limit rather than space.
  • mmuratet 0 Points
    Thanks for the tips. I'm going to head over to the store and get a 16GB card. I can use the 64GB card in my camera. I used the Mac DiskUtility to reformat the 64GB card to FAT32 and it still doesn't work, so I'm guessing that's evidence that Garmin won't support the 64GB card. I can't be in Alabama and idaho at the same time, but having maps of favorite places already stored cuts down on the headaches of travelling. I'll let you know how it turns out.
  • mmuratet 0 Points
    Replaced the 64GB card with a 16GB card. Reformatted the new card to FAT32. Progress meter still goes from -40% to 0% and hangs on second file of Northcentral topo maps. I guess it's in the hands of Garmin support now.
  • mmuratet 0 Points
    I left it plugged in and over the course of the afternoon it eventually finished. I can select features on the map so I conclude it is installed correctly. During the download, which took about three hours, the progress was stuck at 25% and the time to completion went up and down from 13 to 54 minutes. It's the most erratic behavior I have ever seen with any product. I am guessing it is a server-side problem, but I don't know. At any rate, it appears to be working. Thanks for the help.
  • sussamb 798 Points
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