Is there a way to broadcast the HR from my Garmin 245 watch to my laptop for while I’m using trainer road?
If you just want to see it there’s apps like “ HypeRate Desktop App“ that will show it live on screen. No TR required
Seems like you can but I have a 265 and completely gave up on using it for cycling HR. Save your sanity and get a HR monitor (polar verity sense is great).
My Fenix is hopeless for HR on the bike, maybe the Forerunner is better but my advice is to get a HR belt
I have a forerunner 55. On that watch you go to the menu, click “wrist heart rate.” Scroll and click “broadcast heart rate.” Hit the “play/start” button. It gets picked up on TR app via Bluetooth.
Another work around on the Forerunner is to open a virtual run activity and it will broadcast to TR.
My Wahoo Rival has similar functionality. Keep in mind that accuracy is likely compromised at higher degrees of wrist articulation compared to a heart rate strap.
My watch isn’t too bad if you actually set it to broadcast because that forces the sensor into high accuracy mode.
If I just wear it while riding it can be reporting up to half of what my HRM strap does because the watches sensor is in low power mode.
Either way it’s not as accurate as a dedicated HRM though.
I have a Garmin belt but it’s inaccurate
Thank you 
My Garmin strap was showing 188 last night during a recovery ride lol
I’ll try the battery. I’ve had it for a couple years. Not too interested in buying another strap though if I can use my watch.