You missed half that conversation. The guy saying he can’t turn off the light has a Wahoo.
Wahoo doesn’t have 2 connections to the Varia (1 as light and 1 as Radar) it just connects as a radar.
Wahoo, can’t turn off the light and just run the radar.
Garmin can
right after Ray’s comment about using the button:
and
ironic that Wahoo is using Android as the OS, but Elemnt/Bolt/Roam are closed bike computer (no apps).
I saw that. Didn’t want to copy whole thread. Hence why I said:
And Ray said:
“On my 515 I can go to an off-mode, and the radar status light on the side continues to blink, but it doesn’t feed radar data to the ANT+ head unit.”
So I was more unsure how to interpret that statement in bold…
FWIW – I use the German 511 rather than the normal 510 because I don’t like the blink-on-approach on the 510. The 7lm is plenty bright. The 20lm is getting into Eye of Sauron territory if you’re doing AM group rides in the dark.
Main purpose for me would be just radar with light off and occasionally turning a lower light mode on if necessary. Would prefer 515 for more options or outside of Germany. So 515 or 516 would be ok.
If only anyone could solidly confirm on the “no light just radar” mode and its battery life (is it substantially increased? how long?).
In Ray’s review the gen2 RTL510, the comment section has reports that light-off / radar-on is working just search for #144, #147, #149, #151, and with enough evidence I stopped looking at that point.
It would be odd if gen3 515 didn’t support light-off / radar-on via Light Network menu (or Connect IQ app), but stranger things have been known to happen.
Yep thanks. That’s what I assume also. Now it’s just especially the battery life without light that’s interesting.
Im betting you will get 20+ with light off radar on. Day blinking is close to 15-16. And the radar does stay on with 510, 515, 516. You can see this with a small blue light on the side. 510, 515, and 516 are basically the same thing and they seem to provide exactly what you are looking for. Honestly, I dont know why anyone would buy the new “lightless” version. You can’t have too many lights and you have option to turn it off.
And I tested that it works earlier and posted that result somewhere in this post.
I solidly confirmed in post #4. I just don’t have concrete data on battery life. But with light off, it has to be more than 15hrs because the light has to run off of something.
Yep, thanks for your answer. And yes it seems logical to have substantial longer battery life in no light mode - but in that case shouldn’t the no light 315 version have a much longer battery life than 7 hours also?
So nevertheless I still would like to hear concrete experiences on the no light battery lifetime.
Hopefully someone will have a concrete answer for you on battery lifetime. That no light version looks smaller. It’s possible it just has a smaller battery.
Just to clarify. You should remove the current pairing, then re-pair it as a light only and NOT as the default radar that you get from “Search All Sensors”.
So the guy quoted a few times earlier is me. You can’t pair the radar as a light with wahoo, so you don’t get the option to turn the light off but keep the radar on. Garmin you can. So YMMV based on the head unit you have.
I turn my light off with the button on top of radar. You can switch modes that way too.
Yup. I can do that as well. But the radar doesn’t work when the light turns off on a wahoo head unit.
Oh, I see now. Thanks for clarifying that for me. 
Hi, I bought the varia rtl 515 and you can have just the radar on with no light if you press it 5 times. I’m not sure how long the battery last on that setting but the radar works fine without a light on. I’m using a Garmin 520 plus with it.
Trying to get a saddle mount for the Varia rtl 515 as I’m a short arses so my seat post is low. The radar work fine for cars but is picking up parked cars etc. Still gives me a piece of mind on the road as it still picks up cars just fine. Deffo think my mudguard is messing the radar up though as it needs mounted a bit higher. Come on somebody, make a good saddle mount for us short arses, lol.
Great product though, just way overpriced man.
Not official Garmin, but options I found from searching.