T8SG - battery too low! can't save

Hi everyone !

first sorry for my english, it's not my mother langage.

i have a problem.

when i power on my t8sg, the screen is black. By tilting the t8sg and looking at the screen pratically horizontaly, i can read "battery too low can't save"

But the battery was full charge and a have tested it and it is ok.
The t8sg has basic setting ( it is set to mode 4, and loaded model is model76).

I set again t8sg to mode2 and load a predefined model, shut down the radio.

When i power it on again, same msg and the t8sg is back to basic setting .... what is wrong ?

any help will be appreciated.
Thanks for all

I am trying to mod my devo 7e in order to power from 1s liion using pololu step up down.

As soon as devo displays voltage around or lower than 4.5Volt, I get "battery too low! Can't save. The buzzer and circuitry starts to oscillate. This while the power still is perfectly 3v3 at the cpu.

I would like to have can't save message around 2.8V.

Some idea for more simple power circuitry, then use 1 or 2 parallel 18650 with protection and usb charge module.

I got some feedback from Vladimir and worked for me. At first check that your Vbat is displayed correct at your Tx.

For the "battery too low message, can't save" you can setup the threshold for this in Tx.ini, default for my devo 7e it was set to 3900, lowering the value to 3000, I could get rid off it.

I am now running on one single cell Li-ion and a step up down 3v3 regulator, only point the Vbat alarm I cannot set it any lower than 3.3V. But it works.

@Fernandez - As I was dealing with the batt too low message on the T8SG, I had to go into tx.ini with Notepad++ and edit batt_critical=3900 to a much lower value to keep that warning from coming up. I am flying with batt_critical=2800 right now. Also I did observe that you cannot set batt_alarm to anything below 3300 using the transmitter menu buttons, but again using Notepad++ to edit tx.ini works. I was able to lower batt_alarm to 3volts by directly editing batt_alarm=3000. Note that the batt_critical low value will keep the warning message from coming up, but on the T8SG the power down configuration save will still fail for voltages below 3.8 or 3.75volts. To get around that you need to modify the 560K-560K ohm voltage divider. 240K-560K ohms works for me and allows the T8SG configuration save to work to something below 2.8volts, consistent with the batt_critical that I am using.

Arknox wrote: Hi everyone !

first sorry for my english, it's not my mother langage.

i have a problem.

when i power on my t8sg, the screen is black. By tilting the t8sg and looking at the screen pratically horizontaly, i can read "battery too low can't save"

But the battery was full charge and a have tested it and it is ok.
The t8sg has basic setting ( it is set to mode 4, and loaded model is model76).

I set again t8sg to mode2 and load a predefined model, shut down the radio.

When i power it on again, same msg and the t8sg is back to basic setting .... what is wrong ?

any help will be appreciated.
Thanks for all

Are you sure your battery has more than 7.4 volts? You need to measure with your own external meter because the original stock transmitter will report incorrect battery voltages when the battery drops much below that value. The symptoms you mention sound like the battery is low.

One more thought - If the battery voltage is well above 7.4 volts, try disconnecting the battery from the transmitter for a minute or so, and then reconnect, and turn on power. The software power switch can sometimes have a problem at low voltages, and this type of reset can help.

ramunas wrote: @Fernandez - As I was dealing with the batt too low message on the T8SG, I had to go into tx.ini with Notepad++ and edit batt_critical=3900 to a much lower value to keep that warning from coming up. I am flying with batt_critical=2800 right now. Also I did observe that you cannot set batt_alarm to anything below 3300 using the transmitter menu buttons, but again using Notepad++ to edit tx.ini works. I was able to lower batt_alarm to 3volts by directly editing batt_alarm=3000. Note that the batt_critical low value will keep the warning message from coming up, but on the T8SG the power down configuration save will still fail for voltages below 3.8 or 3.75volts. To get around that you need to modify the 560K-560K ohm voltage divider. 240K-560K ohms works for me and allows the T8SG configuration save to work to something below 2.8volts, consistent with the batt_critical that I am using.

Myself I have U7E, but it is moreless identical to the jumper. I use direfctly a single pololu step up step down 3v3 regulator connected to two 18650 liion in parallel.
The batteries I connected them to this module to charge and protect the cell against overcharge and discharge.
www.banggood.com/5Pcs-USB-Lithium-Batter...tml?cur_warehouse=CN
The module input I soldered to the USB 5V line and I charge my U7E via USB port.

Indeed it is required to edit and lower the, batt_critical=2800 overall TX works very well.
Oh and I also bypassed the input diode in my U7E power circuitry, so no more loss voltage drop due to that. and I lowered the resistor as described here above to save at shut down.

Hello,

For my initial problem, a FW update and a file system full wipe has solved my problem.

Hopes it can help someone else