Thread: Which is the limitation to the SD/microSD card size for Garmin devices ?

@Schermann
I agree with sergio2 that your problem maybe isn't to do with the actual capacity [size] of the card itself, but with the amount of data the unit's capable of handling.

All units have limitations as to number of maps tiles and also maps themselves. Numerous small maps with different FIDs will also also trigger a limitation. With an outdoor device you'll probable reach the tiles [segment] limit first as sergio2 stated. While there is not a specific ratio of map tiles to size because of the variation in the sizes of various tiles, it's a fact that it's generally pointless you using a card bigger that 16GB because you will almost certainly exceed the unit's limitations to read all the map data, and your etrex cannot handle more than about 3,000 segments whereas sergio2's montana can handle about 4,000. Auto devices can handle much less again.

That said however, your etrex will maybe even cope with a 128GB SDXC card reformatted from exFAT to FAT32 just as well as a standard 16GB SDHC provided both contain the same data. Did your test involve having exactly the same map data on both the 16 & 32 GB cards? Garmin is now saying this:

Card Size (the amount of storage space on the card)

• 32 gigabytes (GB) - Most Garmin mass storage devices can use cards up to this size
• 64 gigabytes (GB) - VIRB and VIRB Elite
• 4 gigabytes (GB) - Colorado and Oregon 400 series

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The 16 Gig limit as opposed to 32 Gig is recognised by Garmin as an ongoing issue.

The issue of map layering and tile limit is well understood by me and nothing to do with this Etrex firmware issue.

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So I contacted Garmin support and got the following 'non-answer' reply:

"Thank you for contacting Garmin International.

I am happy to assist you with this today.

I sorry to hear that the 32GB Micro SD card(s) aren't working properly in your device. The only 32GB Micro SD card we have tested to see if it will work is the SanDisk 32GB Micro SD HC card. We can't speak for every card made by every manufacturer but that is the only one we know works for sure. We usually don't advise to use a card that large though. For most people a 4GB-16GB will work for almost everything. Sorry for any problems that this may have caused.

With Best Regards,
David 6310
Customer Care - Outdoor Team"

He totally ignored the fact that I'm trying to use a SanDisk card. Oh well, I bought a 16GB card and it works fine, so I'll use it. Irregardless of what Garmin says, I think the new Etrex series has a firmware problem, so the 32GB cards aren't usable. I'm still trying to find someone who's successfully using that size card in their unit.

Originally Posted by Neil

............ it's a fact that it's generally pointless you using a card bigger that 16GB because you will almost certainly exceed the unit's limitations to read all the map data, and your etrex cannot handle more than about 3,000 segments .................
.............. Did your test involve having exactly the same map data on both the 16 & 32 GB cards?

Originally Posted by Schermann

The 16 Gig limit as opposed to 32 Gig is recognised by Garmin as an ongoing issue.

The issue of map layering and tile limit is well understood by me and nothing to do with this Etrex firmware issue. ........

It may well be a firmware issue, but is that an acknowledged fact or just a suspicion by WEAVEJD in the Garmin thread? He said: 'Irregardless of what Garmin says, I think the new etrex series has a firmware problem, so the 32GB cards aren't useable.' The alleged 'non-answer' from Garmin to him regarding practical card size is actually good sensible advice i think and in the real world most users will get by with a 4GB card and would never require, or perhaps even be able to use, a fully loaded 16GB card because of the universally understood limitations.

Regardless of whether there is or isn't a fw issue with the eTrex series coping with cards above 16GB, i do agree with Garmin and i don't advise using bigger than a 16GB card in any unit and that's simply for the reason that we all well understand, i.e. the tile limit. i don't have access to an eTrex to make the test myself. But did you do the test as asked above? Frankly, that's the definitive as to whether your etrex 20 has a problem with the overall capacity of the card itself or just the amount of data on it exceeding the capability of the unit itself. I know WEAVEJD reported negative results for the 16GB with the same data on both it and the 32GB in his eTrex30.

The old chestnut about Garmin only endorsing the card brands SanDisk & Kingston has been around forever and frankly I don't believe it either. I had a funny experience some time back which I reported about a small card I kept exclusively for doing NV backups. Always worked fine in countless units until one day i stuck it in a 2 series and nothing happened, card was ignored. A different card worked in it and the original card worked in everything else i tried it in, just not in that particular nuvi. The card was not read even with a small map on it, just didn't exist for that unit when i checked in hidden inventory. Can't explain that either and it was also either a Kingston or SanDisk. It's a total crock but i understand why Garmin keeps saying it, they can't test every card on the market.

I have the majority of my maps (14 Gig) stored on the Etrex SD card in another folder that is not seen by the Garmin System. I swap out (copy) the maps I need between the SD MAP and SD storage folders so that the Etrex tile limit of 3000 is never exceeded, works fine!



I never store maps in the internal Extrex memory so if the system breaks I can just ghost back the system from storage or Full reset without loss.

By doing it THE FILE TRANSFERS this way I always have the right map for the right location on hand.

I do the same with a 64GB SDXC card reformatted to FAT32 used with my nuvis. Most of the maps are in a folder named Spares and I just move them back and forth to the Map folder as required. Much quicker than copying even with a fast-writing Class 10 [UHS-II] card. It's a convenient way to have a vast amount of map data without swamping the unit. Neat trick!

Interesting question, not so stupid but sort of pointless maybe. I can't answer for you on your Montana [or any other outdoor device at present, 'cos i haven't got one to try with]. But it certainly works on a nuvi to run a txt command on the microSD to delete maps from the Map folder. However, a command to copy from the Spares folder to the Map folder seems to always fail.
The reason I say its sorta pointless is that you need access to a computer to write the update.txt file and add the ldr.bin in any case.