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Frsky R8 PRO receiver AIN2 port not working?
Posted: Fri Sep 11, 2020 3:13 pm
by spadeadam
Hi all,
I am trying to monitor my 4s LiPo battery connecting it via a FBVS-01 (3S connector which gives 6:1 ratio) To the AIN2 port of my R8PRO receiver.
When I discover sensors I only get a A2 voltage reading of 1.7V (ratio set to 19.4 which is 6 * 3.3)
I have measured 16.4V going into FBVS-01 and am getting 2.4V coming out which is fed into Gnd and AIN2 of the R8 PRO
When I try this with my RX6R receiver I get an A2 of 16.4V which is correct.
I have tried 2 x new R8PRO’s with a X9D Plus 2019 and Horus X10S express both running Access 2.1.0
Can anyone help me as I am probably missing something simple
The receiver is being powered via a separate 5V NiMh battery
Re: Frsky R8 PRO receiver AIN2 port not working?
Posted: Sat Sep 12, 2020 8:07 am
by Carbo
There is an (useless) A2 voltage in telemetry, but FrSky RX8Rpro have no AIN2 port at all. Where did you connect FBVS-01?
Re: Frsky R8 PRO receiver AIN2 port not working?
Posted: Sat Sep 12, 2020 3:07 pm
by jtaylor
He is talking about the Archer R8 PRO which does have a A2 input.
I don't have one, but the instructions read like it has a 10 to 1 voltage divider built in and can take an input to 36 volts directly and doesn't need a FBVS-01 or voltage divider. Perhaps somebody that knows for sure can comment as I would hate to see somebody burn it up by putting in more that 3.3v if it can't take it. Below is from the manual:
Voltage Measurement Range via AIN2
(External device): 0-36V
(Battery Voltage Division Ratio: 1:10
Jim
Re: Frsky R8 PRO receiver AIN2 port not working?
Posted: Sat Sep 12, 2020 3:48 pm
by Kilrah
Manual indeed suggests that the divider is built in on that RX.
Re: Frsky R8 PRO receiver AIN2 port not working?
Posted: Sun Sep 13, 2020 6:20 am
by spadeadam
Thank you all for your quick replies, I will try connecting my LiPo directly to the AIN2 and keep my fingers crossed that no smoke appears:)
It would be nice to see a circuit diagram of the receiver
Re: Frsky R8 PRO receiver AIN2 port not working?
Posted: Sun Sep 13, 2020 2:23 pm
by spadeadam
I can confirm that connecting a 3S or 4S LiPo directly to the AIN2 port works ok and gives a A2 telemetry reading corresponding to the LiPo voltage.
Saves using a FBVS-01 or voltage divider
Thank you all
Re: Frsky R8 PRO receiver AIN2 port not working?
Posted: Sun Sep 13, 2020 9:41 pm
by jtaylor
Thanks for confirming.
Re: Frsky R8 PRO receiver AIN2 port not working?
Posted: Tue Oct 13, 2020 11:07 am
by youngstar
Many thanks for that
not tried my R8 Pro yet!
Re: Frsky R8 PRO receiver AIN2 port not working?
Posted: Thu Apr 22, 2021 7:52 am
by medor
Hi all,
I am a rooky in this topic, therefore may I ask for your help? Can you provide a detailed wiring diagram that shows how to connect a 3S (JST-XH 4-pins balance plug) or a 4S (JST-XH 5-pins balance plug) LiPo to the AIN2 port? Is there a "standard" cable for that, or I need to prepare one? Or I am completely wrong, and the LiPo's XT60 is the one that should be connected to AIN2?
Next to the receiver (FrSky SR8 PRO), two additional cables were packed:
- cable 1: black/green/red/white, one end with AIN2 male connector, the other end is open
- cable 2: black/x/red/white, one end with AIN2 male connector (pin 2 not connected), the other end is a Futaba "J" connector with a guide tab, if I am not mistaken.
Could any of these be used in some way?
Re: Frsky R8 PRO receiver AIN2 port not working?
Posted: Thu Apr 22, 2021 3:18 pm
by medor
medor wrote: ↑Thu Apr 22, 2021 7:52 am
Hi all,
I am a rooky in this topic, therefore may I ask for your help? Can you provide a detailed wiring diagram that shows how to connect a 3S (JST-XH 4-pins balance plug) or a 4S (JST-XH 5-pins balance plug) LiPo to the AIN2 port? Is there a "standard" cable for that, or I need to prepare one? Or I am completely wrong, and the LiPo's XT60 is the one that should be connected to AIN2?
Next to the receiver (FrSky SR8 PRO), two additional cables were packed:
- cable 1: black/green/red/white, one end with AIN2 male connector, the other end is open
- cable 2: black/x/red/white, one end with AIN2 male connector (pin 2 not connected), the other end is a Futaba "J" connector with a guide tab, if I am not mistaken.
Could any of these be used in some way?
OK, I think I understand. So, there are basically 2 options:
- Connect the LiPo's XT60 to the AIN2 analogue pins; the receiver will measure the LiPo voltage as such. A custom cable to be created (XT60-to-AIN2 analogue). Is this really a safe method? Shouldn't the receiver be protected in some way?
- Connect the LiPo's JST-XH balance plug to a Battery Voltage meter sensor (e.g. FLVSS), connect the FLVSS to the receiver via S.Port to AIN2 cable. Such cable is shipped with the receiver.
The pros for this solution, in my case, is that it is a clean one, and as a rooky, I should go for a clean solution, probably. Additionally, since I did not buy an offline battery voltage meter (yet), having an FLVSS would be useful anyhow, to be able to check the per/cell voltage of the LiPos I have at anytime.
Is my thinking correct? In any way, just for my interest, how does the safe method for alternative 1 above look like?
Re: Frsky R8 PRO receiver AIN2 port not working?
Posted: Thu Apr 21, 2022 6:38 am
by taurineman
Quick question: If ive connected the AIN2 port directly to my 4S lipo as above, what do i set the Open TX telemetry ratio for A2 at ?
so according to the spec its max input voltage is 36V, its built in voltage divider is 1:10. Does that in effect mean its actual max voltage on the other side of the divider is 3.6V? So my calculation would be:
3.6 * 10:1 = 36
So i use 36 as the ratio in the telem screen for A2? That seems to get it very ball-park. I need to use about a 0.3V offset to get it correct according to my volt meter.
Re: Frsky R8 PRO receiver AIN2 port not working?
Posted: Thu Apr 21, 2022 9:35 am
by Kilrah
Ratio should be "the max measurable value" so yes 36.
Never had one of those receivers but if they do it the same as the older ones the fact they've put a 1/10 divider would lead to terrible resolution/precision so wouldn't be worth more than a ballpark (36V as 256 steps = 0.14V / step, not counting imprecisions)...
Re: Frsky R8 PRO receiver AIN2 port not working?
Posted: Thu Apr 21, 2022 8:51 pm
by taurineman
Kilrah wrote: ↑Thu Apr 21, 2022 9:35 am
Ratio should be "the max measurable value" so yes 36.
Never had one of those receivers but if they do it the same as the older ones the fact they've put a 1/10 divider would lead to terrible resolution/precision so wouldn't be worth more than a ballpark (36V as 256 steps = 0.14V / step, not counting imprecisions)...
Great thanks. Yer, just enough to precision to warn when the motor pack is starting to get low.
Re: Frsky R8 PRO receiver AIN2 port not working?
Posted: Tue Apr 26, 2022 6:59 pm
by notas
medor
I hope that someone answers you about option 2, because I am with the same receiver and the same voltage sensor. And I want to have the voltage of each lipo cell on the radio.
Greetings
Re: Frsky R8 PRO receiver AIN2 port not working?
Posted: Tue Apr 26, 2022 10:10 pm
by Kilrah
If you want all cells you need a separate sensor like the FLVSS.