Frsky Tandem x20 Tx Battery Voltage reading incorrect

[Pierre]

Tx read it's battery voltage at 8.1V. Battery checker and charger reads it as 7.5.
My tx battery low warning is set at 7.5v. When it reaches that the tx battery is at 7v....read by battery checker.
Any idea or setting to get a true battery voltage reading?
Yes the max is set at 8.4v as this is the full value reading for a 2s Lipo.

 

[Chris]

You can change the readout in the Battery page of the System menu. Just touch the voltage that it shows and use the + and - at the bottom. Between the words Min - Default + Max...

 

[gnichola]

Interesting @Chris and that is a nice workaround, but really, shouldn't the actual voltage reading be properly calibrated? That doesn't seem like a lot to ask

 

[Pierre]

I charged the tx battery externally to full; I.E 8.4v
Set the tx batt section to 8.4v. This i knew btw.
I shall monitor it when tx gives low reading; 7.5v and then check it with batt volt/% checker, i do prefer to work on volts rather than % as this has gotten me in trouble in the past.
Will get back, As of yet i have not flown any of my planes with this system. 3 giant scale planes(2 big gassers and one glider) to setup again and "re-maiden" with Frsky system. Also waiting on some Rx's and RD's.
In the meantime with my fooling about, range testing/setups/tx know hows(2 x R10 Pro's in "daisy chain") etc, pretty sure i'll be able to report back with results.
@gnichola yes, i would also think that it is a function that should be done by the tx. As you also have to calibrate the rx battery reading.....bit of ball drop there for me from Frsky.
But so far the only cons i can find. I come from Spektrum.....16 years later and not a days worth of problems, this is like moving from an Apple phone to Samsung....the long way round ha ha ha ha ha ha. But this was a pure financial decision.

 

[gnichola]

Also, if you go in there and mess with the value, without really knowing that is what you are doing, how do you get back to "default"?

 

[Pierre]

Also, if you go in there and mess with the value, without really knowing that is what you are doing, how do you get back to "default"?

You talking about Rx battery reading now?
If so, i attach a battery checker to my battery and then keep on turning the dial when in rx battery calibration mode, until the tx read to the same rx batt volt as the external batt checker.
This i have figured out to be correct, as the rx batt volt drops the tx shows it accurate according to the voltage checker.
For the Tx batt i just set the max to 8.4 and min(warning) at 7.5v, this is what i will still figure out, if it is reading the tx batt correct.
Within a couple days when the voltage reading has dropped to say 7.9 i'll remove the tx batt and check it with the battery checker to see if both reads the same.
Really wonder why they made it this complicated, name any system, Spektrum, JR, Jeti, Core etc etc, when running telemetry on rx battery it gives the "honest" volt reading, tx batt reading also true and not like i have experienced with the x20.
These two readings are rather IMPORTAND !!!! One would think it would be the first thing to be accurate on a tx telemetry. I've seen that the x20 just shut down when tx batt voltage is to low..........hence me having it now on 7.5.
Once again Spektrum, you can go as low as 6.8 and no tx shutdown, x20 shut down at 7.1 in think it was. But i always go charged up to the field, rx and tx batts, my planes are way to dear to be downed by a "pilot" error like that.
PS. I do not think there's a default setting concerning the rx battery, mine was zero it is now on .51 to read the rx battery correct.