Heart rate very high since 5.50

I have the same problem - and gone through all the HR troubleshooting advice. However, this has been apparent for about 4-5 months ; the start and end of my workout it fails to pick up and the HR then goes through the roof  (

You can expect the built-in HRM to be as accurate as a chest strap or external HRM.

You can expect it to be so but quite evidently for many people right now it is far from accurate.

I've gotten slightly better results on runs in the second half of the week by wearing the watch about half an inch farther up on the forearm. Seems that running motion is affecting the sensor in some way? My average HR is still ~10-20 BPM higher than I would think, but that's certainly an improvement. I guess what I am seeing is that the increased sensitivity of the new sensor hub is causing spikes with a significantly higher amplitude than the previous version.

Here's a nearly identical route, at nearly identical pace, with nearly identical weather conditions, before and after the update. Both runs were an easy perceived effort (I say this based on 20 years of competitive running as experience). The post-update run (left image) not only has a greater discrepancy between peaks and troughs, but also much higher highs (180-185) compared to the pre-update run (right image) which tops out at (155-160). As I noted, the average BPM is actually not too far off (10-15 BPM) but that can be the difference between the algorithm thinking that I am working very hard and it thinking that this was the easy run that it actually was.

Not a huge difference but certainly noticable.

I've been having the exact same problem. I think it started at least two months ago, but firmware 5.5 and the cold weather seem to exacerbate it. My HR will jump from 145 to 180 and then back down to 150 in a matter of seconds, and like others mentioned, it's destroying my Vo2 Max calculation. Has Garmin offered any solutions? 

I've been having the exact same problem. I think it started at least two months ago, but firmware 5.5 and the cold weather seem to exacerbate it. My HR will jump from 145 to 180 and then back down to 150 in a matter of seconds, and like others mentioned, it's destroying my Vo2 Max calculation. Has Garmin offered any solutions? 

The official line is that they do not look at these forums. I understand that there are manpower resources required but if I was in their position I would keep an eye out without engaging for warnings of problems. There is some effort involved but it is possible to determine signal from noise if issues are raised in a reasonable fashion with evidence to support what is being said.

My workaround with a Polar HR is not what I would ideally like but it gets me to my desired result. It has the added bonus of having software that makes me appreciate Connect a lot more.

Right. Ironically, I tried that workaround myself by getting a Wahoo Tickr X.  But unfortunately by FR245 constantly drops the signal from the strap, so the workaround falls flat on its face. I'm honestly so frustrated with the 245 that I'm considering switching to Polar. 

Other than the software being pants and the record to device setting being very difficult to tell when it is engaged, the Polar OH1 has worked very well and the two drawbacks are negated if you simply use it as an external HR for the 245 as the watch does the recording and you don't need to care about the Polar software.