SRM - Garmin Fenix 7X Power Drops

[OJ]

Have to bring this to forum crowd for advice after SRM not being too helpful. Thank you for any advice in advance.

I had both of my SRM powermeters serviced by SRM in 2021. Ended up selling older PM5 and installed newer PM6 onto my Praxis cranks last July (2023). My thinking was, that I'd keep the newer meter. The PM6 had been sitting on the shelve since the service. Also last year I upgraded my watch to Fenix 7X. Right from the start I started experiencing power drops, not short, not consistent in length or when the drops happened, just random drops where power went to 0. I've tried MANY different magnet set-ups from DIY to current K-edge cadence magnet, and tweaked the magnet position MANY times. None of the magnets perform better or worse. The SRM wakes up, and always works well at the start of the ride, but after 2-15min start dropping the power. Sometimes the power comes back, and stays connected for longer periods of time, or even for the rest of the ride, but more often I just get little bits along the way. Of course I have tried different watch locations anywhere from watch on the wrist to watch mounted on downtube. I have also tried the watch with different powermeters, and my Neo 2T trainer, and these work perfect. I have also tried Garmin Edge head units with the same problems.

Is SRM & Fenix 7X a known non-compatible combo? Is there some known fix for this? Any advice/ideas, I'm open to almost anything at this point?

Having said all this, PM5 & Fenix 5X (and Garmin Edge) combo worked near flawless.

[MichaelK]

PM6 would be a single EF651625 battery IIRC. Could have gone bad by sitting for 3 years, I probably change that first and see what happens.

[ms6073]

Is SRM & Fenix 7X a known non-compatible combo? Is there some known fix for this? Any advice/ideas, I'm open to almost anything at this point?

Which wrist are you wearing the Fenix on? I don't have my Fenix 7X connected to my DA powermeter, but back when I had the 5X paired with a Hollogram SRM for cyclocross, I found that if I wore the watch on my left wrist (non-drive side), I would get data loss on occcasion. While not a cure all, moving the watch to my other wrist helped, but I would also mention that dying SRM batteries will also contribute to this and would ask, is the zero-offset holding steady or is it gradulally going up/down? If so, probably time to replace the battery(s) again.

[OJ]

PM6 would be a single EF651625 battery IIRC. Could have gone bad by sitting for 3 years, I probably change that first and see what happens.

Was kind of thinking this might be the case, and just hoping I have missed something really simple/stupid. Might get a new soldering iron, and try myself, sending to SRM on Canadian $ seems bit steep.

[OJ]

Been doing some "tests". July was warm and dry here, and I experience next to no power drops. I'd say everything worked as well as I could expect. Then came last weekend, we went to spend a weekend with a family, and I brought my bike with me. Got there Friday night, and put my bike under the terrace/sunroom/thing, so outside, but under a roof. Saturday morning there was dew on everything as it's by a lake, and when I went riding on Saturday, the power dropped off after about 5 minutes. Road was wet in spots during the ride, and the power came on only sporadically. I think the SRM is somehow sensitive to water/humidity, which is pretty annoying even for a fair weather cyclist such as myself.

I need to ask SRM service if this is something they are familiar with before I send the PM in for service.

[OJ]

Monologue continues.

The problem persists. Some rides the PM works almost the entire ride, some days it doesn't really work at all. Not confident that SRM would fix the PM if I sent it to them. The PM is in this state after their service, so don't feel like spending good money after bad.

Ordered 4iiii PM...