My cardio watch is about 6 years old and the battery only lasts 3-4 hours when using the gps.

Margo1

Would a new battery help and where do I get this done

nabu

https://www.ebay.fr/itm/Rechargeable-Battery-1-04Wh-280mAh-for-TomTom-Spark-3-GPS-Fitness-Watch/264307661968?hash=item3d89f6dc90:g:ZVcAAOSwPR9bpMmn

tfarabaugh

There is no service for this, you would have to do it yourself by getting the right tools, opening the watch, figuring out which battery you need, buying the battery and installing it (which may require soldering). You would be better off just getting a new watch, there are plenty of brands out there with better feature sets for less money these days (TT Sports went out of business over 2.5 years ago).