A friend who is a bit visually impaired wants to use his I-Phone as a gps which will give voice directions as well as text cues.

Ridewithgps has an app that is listed as doing this. Have any of you used this and what are your experiences?

Also, he would need an external battery to power the phone as I assume it will probably not last more than a 4-5 hours with the I-Phone's internal one. He would like to be able to ride a century and up to a 200k brevet so would need power for about 12 hours. Any recommendations on external batteries and is there a special cable needed that allows the phone to charge and still run as a gps at the same time?

Thanks,

Jim

He could use a Mophie Juice pack but that only gives one extra charge. Better to get an external battery pack from Mophie of Anker. He just needs a lightning cable, it should affect the gps.