While waiting for parts for my nanoLongRange i had the idea to build a 2S or 3S LiIon 4inch aswell.

Checking my parts boxes from some years ago i found some RCX h1304 5000kv motors, an R-XSR receiver AND some nice woven 6/4mm carbon rod that would make a lightweight frame. I designed, cut and glued the frame and printed some motor adapters for the 6mm tube. The dry weight is ~100g now, so in theory it would be doable to do a 3S18650 below 250g, but the motor/prop combination works way better on 2S.

Running 2S LiIon brings up some other problems as the battery voltage ranges from 8.2-5V. 5V is to low for most of the 2-4S AIO Boards, the BEC will not output 5V anymore so you need to use a 5V step-up-down converter for VTX, Cam and maybe RX. The even bigger problem is that the integrated ESCs stop to work below ~6.2V which makes a lot of capacity of the 18650s unusable. This is mostly due to an upstream 12V regulator (+Diode on some boards) on the AIO/ESC board which limits the input voltage on the rest of the electronics to 12V is used with more than 3S. By bypassing the regulator and a diode i could get my board to work down to 4.6V (6.2 before the mod). Nic did a great Video on how and why to do this, see the link below.

First tests look very promising, hat problems with my first cam which prevented me from doing real FPV flights. This one was just not flying nice, guess depending to the 2S LiIon beeing to low and the floppy props causing vibrations on the not so stiff frame. Lets go on with a modified 3S version of it: LR43 flat

• How to modify your AIO/ESC to work on 2S LiIon by Nic

JHEMCU GHF13 AIO - MATEK F411

orig:
I2C1_SCL              B08        // SCL pad
I2C1_SDA              B09        // SDA pad
RSSI_ADC_PIN          A00
LED_STRIP             A08

changed:
resource LED_STRIP 1 none
resource SERIAL_TX 11 A08
resource SERIAL_RX 11 A08
resource RSSI_ADC_PIN none
resource servo 1 A00
save

JHEMCU GHF13 AIO - MATEK F411

orig:
I2C1_SCL              B08        // SCL pad
I2C1_SDA              B09        // SDA pad
RSSI_ADC_PIN          A00
LED_STRIP             A08

changed:
resource LED_STRIP 1 none
resource SERIAL_TX 11 A08
resource RSSI_ADC_PIN none
resource servo 1 A00
save

set serialrx_halfduplex = ON
set serialrx_inverted = OFF
save

# vtxtable HGLRC Zeus Nano
vtxtable bands 5
vtxtable channels 8
vtxtable band 1 BOSCAM_A A CUSTOM  5865 5845 5825 5805 5785 5765 5745 5725
vtxtable band 2 BOSCAM_B B CUSTOM  5733 5752 5771 5790 5809 5828 5847 5866
vtxtable band 3 BOSCAM_E E CUSTOM  5705 5685 5665 5645 5885 5905 5925 5945
vtxtable band 4 FATSHARK F CUSTOM  5740 5760 5780 5800 5820 5840 5860 5880
vtxtable band 5 RACEBAND R CUSTOM  5658 5695 5732 5769 5806 5843 5880 5917
vtxtable powerlevels 4
vtxtable powervalues 25 100 200 350
vtxtable powerlabels 25 100 200 350