Thanks everyone, some very good suggestions.
Here is what my plan is.
I have a Galaxy S3 phone that I'm not using at all, it's not "connected" to any cell service provider, it's just a spare phone. I found a 7000mAh extended battery and case on Amazon for $40.00, I'm going to give it a try. I like the idea of using the phone as a dedicated GPS device for other activities other than cycling such as back country hiking etc because I can download maps to the phone as well. Plus I can upload to Strava wireless. For rides 200K or less, I can use my Edge 305 and for greater than 200K I'll use the phone. Size really won't concern me too much as I always change out the smaller saddle bag for a larger one to accommodate the extra gear for longer rides, I'll stuff it in the bag or perhaps my jersey pocket if it isn't to gaudy.
If that doesn't suit my needs well then I'll try one of those portable chargers velcro'd to the the Edge 305.
As a side note, one of the things I liked about the Galaxy phones is the ability to use the GPS while the phone is in "Airplane" mode. This will save a lot of battery. My current iPhone will not do this, once the phone is placed in "Airplane mode", the GPS shuts down as well. Stupid IMO.
Last edited by c_bake; 05-12-14 at 02:29 PM.