Real GPS devices such as Mio, Wahoo and Garmin usually last far longer than one day. Most types also let you change their batteries, but with a charged GPS, you can usually use your device for several more days. Why is that?
- Your GPS has a processor that is far less powerful than the one in your phone device. Don't forget that your current phone device has a far more powerful processor than the first PC you ever purchased. This is why you can do so many fantastic things, like video calls, playing videos, taking nice pictures... But that comes with a cost. And it is not just the cost of your phone, but the energy cost as well. Your GPS (and the processor that comes with it) is chosen to do what it has to do: navigate. On the other hand, though a GPS is not that multifunctional and is less powerful, it is also far more energy efficient.
- Your GPS has a screen that uses far less energy than the one on your smartphone. This is why your smartphone has much nicer colors. Some GPS devices even have a passive screen.
- Scanning frequencies to find which satellites are sending out a signal also involves a lot of energy. That's why a great number of GPS devices have a frequency reference chart that depends on your position and the time. This means that that chart knows - if you are at LAT, LONG location at a certain moment - which satellites are "visible" for your GPS. As a result, it does not need to check the frequencies of the satellites that are not visible, which saves you some energy. However, that trick can also be applied to your smartphone,
so it's give and take.