Since I haven't seen this anywhere else yet, here's a relatively easy mod to enable the cheap and light iA6 receiver to monitor flight battery (or any other) voltage instead of the RX own regulated power and send that back to the i6 or i10 TX.
On the first pic is the ADC input circuit for the RX voltage telemetry, it's a 1/10 (I suppose, mine is more like 1/11, the resistors being 47,1k and 4,77k) voltage divider and is connected to the + pin of channel 1. The + pins of all channels are connected together on the other side of the PCB, all that's needed is to separate the voltage input from the rest. Remove the cover, wiggle the plastic spacer off the pins and just cut the trace between the two pins like on the second pic.
Now, instead of that useless RX voltage from the BEC, you can have some other voltage sent back to the TX and displayed on the screen without any additional sensors.
I tested this with 3S battery (up to 12,6 volts) and the i6 TX displays it nicely, but I don't know what the real upper limit is. RX voltage alarm works fine too, the only small problem is that the i6 TX will let you set RX battery level up to 10.0 volts and the alarm can only be set up to 9.8 volts. If that is not suitable, it's possible to reduce the telemetry voltage by half by connecting a 51k series resistor with the voltage input, only have to remeber that the displayed voltage is then half the battery voltage, but you can set the alarms more freely (I have mine set to 5,4V, which then means 10.8 volts flight battery voltage).

Edit: The mod for iA6B is in post #23

Originally Posted by triibutu

Since I haven't seen this anywhere else yet, here's a relatively easy mod to enable the cheap and light iA6 receiver to monitor flight battery (or any other) voltage instead of the RX own regulated power and send that back to the i6 or i10 TX.
On the first pic is the ADC input circuit for the RX voltage telemetry, it's a 1/10 (I suppose, mine is more like 1/11, the resistors being 47,1k and 4,77k) voltage divider and is connected to the + pin of channel 1. The + pins of all channels are connected together on the other side of the PCB, all that's needed is to separate the voltage input from the rest. Remove the cover, wiggle the plastic spacer off the pins and just cut the trace between the two pins like on the second pic.
Now, instead of that useless RX voltage from the BEC, you can have some other voltage sent back to the TX and displayed on the screen without any additional sensors.
I tested this with 3S battery (up to 12,6 volts) and the i6 TX displays it nicely, but I don't know what the real upper limit is. RX voltage alarm works fine too, the only small problem is that the i6 TX will let you set RX battery level up to 10.0 volts and the alarm can only be set up to 9.8 volts. If that is not suitable, it's possible to reduce the telemetry voltage by half by connecting a 51k series resistor with the voltage input, only have to remeber that the displayed voltage is then half the battery voltage, but you can set the alarms more freely (I have mine set to 5,4V, which then means 10.8 volts flight battery voltage).

Very interesting your modification !

I wonder if it is possible to modify iA6B in a same manner.

I am using iA6B because the receiver range is better. Add a sensor for it is not very expensive, but it adds wires and plugs... It would be better if TGY iAxx receivers had be designed to support a plug for the main battery. You are right in your concept !

Originally Posted by Denis Poulain

I wonder if it is possible to modify iA6B in a same manner.

It seems possible to mod iA6B the same way, but it's not easy and requires some decent SMD skills. The ADC input is on the PCB and not easily accessible near the servo pins. Since the PCB and components are very tiny, it's probably beyond most people's abilities.

Originally Posted by triibutu

Since I haven't seen this anywhere else yet, here's a relatively easy mod to enable the cheap and light iA6 receiver to monitor flight battery (or any other) voltage instead of the RX own regulated power and send that back to the i6 or i10 TX.
On the first pic is the ADC input circuit for the RX voltage telemetry, it's a 1/10 (I suppose, mine is more like 1/11, the resistors being 47,1k and 4,77k) voltage divider and is connected to the + pin of channel 1. The + pins of all channels are connected together on the other side of the PCB, all that's needed is to separate the voltage input from the rest. Remove the cover, wiggle the plastic spacer off the pins and just cut the trace between the two pins like on the second pic.
Now, instead of that useless RX voltage from the BEC, you can have some other voltage sent back to the TX and displayed on the screen without any additional sensors.
I tested this with 3S battery (up to 12,6 volts) and the i6 TX displays it nicely, but I don't know what the real upper limit is. RX voltage alarm works fine too, the only small problem is that the i6 TX will let you set RX battery level up to 10.0 volts and the alarm can only be set up to 9.8 volts. If that is not suitable, it's possible to reduce the telemetry voltage by half by connecting a 51k series resistor with the voltage input, only have to remeber that the displayed voltage is then half the battery voltage, but you can set the alarms more freely (I have mine set to 5,4V, which then means 10.8 volts flight battery voltage).

So after cutting the trace i can jus connect the pins of say mayb channel 6 to tbe flight battery? Or is there another step? Thx

Originally Posted by triibutu

Since I haven't seen this anywhere else yet, here's a relatively easy mod to enable the cheap and light iA6 receiver to monitor flight battery (or any other) voltage instead of the RX own regulated power and send that back to the i6 or i10 TX.
On the first pic is the ADC input circuit for the RX voltage telemetry, it's a 1/10 (I suppose, mine is more like 1/11, the resistors being 47,1k and 4,77k) voltage divider and is connected to the + pin of channel 1. The + pins of all channels are connected together on the other side of the PCB, all that's needed is to separate the voltage input from the rest. Remove the cover, wiggle the plastic spacer off the pins and just cut the trace between the two pins like on the second pic.
Now, instead of that useless RX voltage from the BEC, you can have some other voltage sent back to the TX and displayed on the screen without any additional sensors.
I tested this with 3S battery (up to 12,6 volts) and the i6 TX displays it nicely, but I don't know what the real upper limit is. RX voltage alarm works fine too, the only small problem is that the i6 TX will let you set RX battery level up to 10.0 volts and the alarm can only be set up to 9.8 volts. If that is not suitable, it's possible to reduce the telemetry voltage by half by connecting a 51k series resistor with the voltage input, only have to remeber that the displayed voltage is then half the battery voltage, but you can set the alarms more freely (I have mine set to 5,4V, which then means 10.8 volts flight battery voltage).

Hello, I'm about to do this mod and see.. But one question I have.. Once you break the link , where does the servo for Channel 1 get it's power supply from? Or is there something I'm not understanding.. Sorry if it's a stupid question but my first RC

Originally Posted by FutureX_ACE

So after cutting the trace i can jus connect the pins of say mayb channel 6 to tbe flight battery? Or is there another step? Thx

No. Only the middle pin of channel 1 will become voltage sensor input, all the rest remain as they were. So if you connect flight battery to channel 6 and this flight battery is >2S, you will have the excuse to buy some new electronics.

Originally Posted by ahamerh

Hello, I'm about to do this mod and see.. But one question I have.. Once you break the link , where does the servo for Channel 1 get it's power supply from? Or is there something I'm not understanding.. Sorry if it's a stupid question but my first RC

Well, servo 1 will have to get it's power from somewhere else then, so you'll need to get creative with the wiring a bit.

Originally Posted by ahamerh

Hello, I'm about to do this mod and see.. But one question I have.. Once you break the link , where does the servo for Channel 1 get it's power supply from? Or is there something I'm not understanding.. Sorry if it's a stupid question but my first RC

Ok, I did it and yes it does read the voltage correctly from Channel 1, center pin.
I guess if you want to still use channel 1 to drive a servo, you need to power the servo from one of the other channels instead by splicing it in.

Originally Posted by ahamerh

I guess if you want to still use channel 1 to drive a servo, you need to power the servo from one of the other channels instead by splicing it in.

Correct.

Here is the wiring after I did the mod suggested by "triibutu"

I've also taken a reading with a volt meter and there is a little bit of a difference from actual battery voltage to reported voltage.

I will probably also add the 51k Ohm resistor in series to the sensor input on channel 1 to halve the voltage so I can use the alarm function on the remote.

Would be nice if there was a new FW for the i6 TX to allow us to use a higher voltage for alarm setting rather than the 10v max.

My guess is the resistors in the original voltage divider are not very accurate to begin with.
Also the 51k may need to be adjusted if you want to get more accurate readings. I just used a 100k linear pot and trimmed it until the TX display matched half of the real voltage, then measured the resistance and replaced the pot with close enough fixed resistor.

Originally Posted by triibutu

My guess is the resistors in the original voltage divider are not very accurate to begin with.
Also the 51k may need to be adjusted if you want to get more accurate readings. I just used a 100k linear pot and trimmed it until the TX display matched half of the real voltage, then measured the resistance and replaced the pot with close enough fixed resistor.

I just came back from the first test flight with the new setup.. I set the alarm as high as it could go on the remote and as soon as I got the alarm I probably had about 30s of flight time left.. Flaps out and landed

So the fact that the sensor is under-reading the voltage was good, but I think adding the resistor is the final solution.

Originally Posted by ahamerh

Would be nice if there was a new FW for the i6 TX to allow us to use a higher voltage for alarm setting rather than the 10v max.

I agree !

And it would be nice too if a new firmware adds the possibility to have multiple alarms : for example one for the voltage sensor of the iA6B or iA10, one for the feedback sensor data from RX (Err 1 - Rx error percentage ?), and I imagine one for a temperature sensor, etc...

Originally Posted by triibutu

My guess is the resistors in the original voltage divider are not very accurate to begin with.
Also the 51k may need to be adjusted if you want to get more accurate readings. I just used a 100k linear pot and trimmed it until the TX display matched half of the real voltage, then measured the resistance and replaced the pot with close enough fixed resistor.

Excellent work Triibutu.

I think the voltage divider is supposed to be a 11:1 ratio, the nearest standard resistors are 4.7k and 47k.

The hidden menu has a TX battery calibration menu option, I am not sure if that also influences the RX voltage display.

Works for me, thanks for Triibutu ;-)

Hi all, haven't posted in a very long time but I thought I would add to this post. this is to mod the IA6B RX so that you can monitor Main Pack Voltage or any voltage without add the TLM Modules. Really no need to monitor the Regulated 5.0V from the ESC. If that is bad you are probably going down anyways. Also on the previous mod for the IA6 if you cut the trace between the headers and the resistor and add a wire, you won't have to worry about trying to plug into the servo connections or supplying the wrong voltage to the rest of the board. Again for fine tuning you could add a 50K pot in this line you added and shot for 1/2 the battery voltage. easier to set the alarms now.