RadioLink R7FG - 8s voltage telemetry!?

[stock20]

Hello all,
I have the RC6GS V3 and R7FG TX/RX combo. I'm interested in using the vehicle battery telemetry function on a Kraton 8s. The included "voltage telemetry connect cable" is not going to work with QS8 connectors and 8awg wire. Can I just open up a spot on ESC +/- power wires and solder in the JST cable? Also, can I really run 8s directly to the receiver??? This seems insane to me, but I have no idea how it works, given there is a special port on RX for this function. (Manual states up to 8s is supported for vehicle battery telemetry)

Thank you

 

[SrC]

Just Solder JST leads to the ESC leads, being mindful of correct polarity, close to the ESC. Just cut a notch in each ESC lead, to reveal a tiny spot of bare wire, and solder directly to it. Use Liquid Electrical tape over the solder to seal and isolate the joints. The JST plug goes into the Rx. ( bus port) I did this Voltage Telem connection on my Lim. using the same Radio/Rx combo. You won't need that whole Inline adapter there, just the JST connector and it's leads. It should plug into the Rx Telem port no issue. No need to touch/alter the QS8's at all.

>>>>>>NO, never plug 8s volts directly into the Rx standard ports
It will probably go on fire. Rx will be toast.
>>>The manual is just stating that the Radio can read as high as 8s Volts in its Display. And the Radio offers a Lipo alarm voltage setting as well. Only If plugged into the Telem Bus port. Hopefully I understood you correctly.

I'll try to send you a pix here of my Lim setup, if you need, to give you an idea.

Good luck.

 

[stock20]

Solder to the ESC leads close to the ESC. Just cut a notch in each leadf and solder directly to it. Use Liquid Electrical tape over the solder to seal and isolate the joints. The JST plug goes into the Rx. ( bus port) I did this Voltage Telem connection on my Lim. using the same Radio/Rx combo.

>>>>>>NO, never plug 8s volts directly into the Rx!
It will probably go on fire. Rx will be toast.

I'll try to send you a pix here of my Lim setup, if you need, to give you an idea.

Good luck.

Awesome thanks, that would be great. So 8s is okay for the telemetry port then? That port must be completely isolated from channel ports.

 

[SrC]

Yes Isolated from the Channel ports.. And I believe your ESC has a BEC output selectable only as high as 8.4 volts FWIW. (at the Channel Ports)
Not to confuse further. Only plug Telem into the Bus Telem Port.
You got this.

 

[stock20]

Great, thanks again. Helpful pics too. Your cable routing inspires me to try and do a better job of it!

 

[SrC]

When I just took pix of my Lim, I just noticed in the close up pix, that I had smashed 2 of 3 of my Capacitors on my XR8 ESC. From a side wreck this summer. The ESC still works, But I may need a new one soon. IDK. I run a cap pack anyway.
Funny how I just noticed. Haven't run my Lim for quite a while. I have to travel far to speed run it.
Thanks to your thread I just noticed that.

 

[stock20]

Hey @SrC what do you use as a voltage alarm? Stick to 3.2v/cell or a little higher? (Or disable alarm?)
Got this wired up on mine and really liking it.

 

[SrC]

Telem won't read each lipo cell !
So multiply the number of cells times 3.4v or 3.5v /cell. Depending on the Lipo pack cell count. 4s or 6s. Personally, I feel 3.2/cell is rather too low. But is fine to start off.
If running a 6s pack for instance, 6 x 3.4v/cell = 20.4v total (Fully charged being 25.2v total pack volts) 20.4v being set as the alarm at the Radio.
You have to drop volts down some If you get premature alarms., Some cells may dip low briefly and may trigger the alarm prematurely . And is not really a sign that LVC will necessarily soon cut in.
"Trial and error". You also can start with 3.2v and work your way up. No problem. This Telem just gives you a rough idea through the radio. ESC's LVC takes charge with Cut off points. When LVC does Cut-Off, make note of the Radio's Telem Lipo volts at that time, to gage yourself and the lipo next time you run. Different lipos may vary.
Enjoy your RL radio.

 

[stock20]

Telem won't read each lipo cell !
So multiply the number of cells times 3.4v or 3.5v /cell. Depending on the Lipo pack cell count. 4s or 6s. Personally, I feel 3.2/cell is rather too low. But is fine to start off.
If running a 6s pack for instance, 6 x 3.4v/cell = 20.4v total (Fully charged being 25.2v total pack volts) 20.4v being set as the alarm at the Radio.
You have to drop volts down some If you get premature alarms., Some cells may dip low briefly and may trigger the alarm prematurely . And is not really a sign that LVC will necessarily soon cut in.
"Trial and error". You also can start with 3.2v and work your way up. No problem. This Telem just gives you a rough idea through the radio. ESC's LVC takes charge with Cut off points. When LVC does Cut-Off, make note of the Radio's Telem Lipo volts at that time, to gage yourself and the lipo next time you run. Different lipos may vary.
Enjoy your RL radio.

Ha, thanks. I knew about the cell multiple. I wouldn't dare set 3.2v cutoff when I start with 33.6v! . Was just trying to put it in general terms with "per cell".

You still answered the question though and great point on LVC reference. Was trying to find a good balance between premature beeps and something too low. Started with 3.5v (28v). Might go down to 3.4v.

 

[SrC]

Yeah don't stress it much. The telem volts and alarm is just a nice reference when bashing. I like to stop running way before LVC cuts in. So this helps. Especially when I speed run. Nothing worse than LVC cutting in at the big end of a pass. Carnage......... Been there.