FredI just read your great write-up on adding (and organizing) POI files on the Garmin. Well done! Will the Garmin recognize the files if they are stored on an auxiliary card rather than in the unit's main memory? Works for routes (and apparently maps but haven't tried it). Even on the Zumo 665, there is precious little additional main memory available after installing some of the recent LARGE mapsets. I've deleted all of the "extra" languages/voices/vehicles etc. to maximize space but don't have a very large amount of leftover for POIs. Does the system slow noticeably if you invoke the extra POI files? If it is displaying the stuff on the screen, the points must be "living" in the active memory.
I believe that you can put them on the SD card in the same directory structure that they exist on the unit's internal memory (/Garmin/Poi ) and it will find them. However, I never do that. I just load them onto the device's memory because I have all of my mapsets loaded to the SD cards, which leaves the device memory essentially empty.
I have posted the detailed instructions for doing that (loading full mapstes onto SD card)
here. IMO, it is worth doing that on
any older Garmin GPS these days as their mapsets continue to grow in size, even the zumo 66X units are getting short on internal memory.
I did not realize that the added POI would show up as screen icons - very helpful. It would be nice if Garmin provided the means to edit the stock POI file that comes with the map downloads. I'm sure they take up a large amount of space and the only things I regularly search for are gas stations, hotels and places to eat.
Yes, the custom POIs are live and get placed on the map in real time. And, if you place a proximity alert in the POIs you will get an alert tone and banner with the POI name across the top of the display whenever you get within the proximity distance you set. For instance, I have a POI file with all 235 of the New Hampshire historical roadside markers with the proximity alerts set to 1/4 mile. Anytime I get within that radius of a marker it alerts me to its presence. I like collecting the photos of the markers with my bike.
I think you are correct that the POIs in the map updates accounts for the majority of their ever increasing sizes. The roads don't really change all that much but new POIs are always being added, and old ones don't always get deleted. I'm not aware of a way to edit the POIs in the mapset, but it really isn't an issue if you load your maps to a big SD card