Steel,
I had the exact same thing happen to me this year. My spedo is a Livorsi but I believe they both use the same antenna. I called Livorsi & they confirmed for me that Yes there is a battery soldered into the antenna puck & it lasts about 4 to 5 years. They had me send it to them & replaced the battery for $75.00 & the battery will last another 4 to 5 years. I put it back in the boat & everything is perfect & back working. Call Gaffing & I will guaranty they tell you the same thing. I know it seems stupid but there is a battery in the antenna puck that you can not replace on your own.

Dave

Skill dependant, yes you can. Its a small watch type battery. If you can solder, you can change it yourself.

The battery will charge if you leave the gps on for 24 hours ,you will find you'll have to do it evry few weeks since the battery is old & gettin weak