Can you replace the battery easily?

The battery in my Nuvi barely lasts any time at all and with a finicky charger, this means it will tend to quit in the middle of a trip. I was able to sort of see the battery in the disassembly guide, but I was wondering if the connection is soldered on or if I could open it up and get a replacement, possibly even a bigger one. Anyone happen to know?

I only use it for long trips now where I want to conserve my battery on my phone so I may just bust it open and see anyway.