Charge Node

Boards / The whole charge node as one schematic, for review. The sense board and the power stage are the boards that are built.

This schematic shows the full aircraft charge node in one project, for design review.

Revision: A rc6
Sheets: 5
Parts: 112
Location: aircraft
Bus: DroneCAN, aircraft CAN bus 2
Status: Rev A: review schematic only, no layout

What it does

The charge node makes the dock charge path safe without a person present. It is a DroneCAN node that runs ArduPilot AP_Periph. It reads the six cell voltages, the pack voltage, the charge current, the charge plate voltage and the pack temperature. It drives the charge-enable switch and the balancer power switch. A Lua script on the FC, charge_interlock.lua, decides when each switch closes.

The plate voltage also carries the dock “site clear” signal: 12 V on the plates, which the FC reads as battery 3.

This project is the full node as one schematic, so that a reviewer can read the circuit in one place. It has no layout. The node is built as two boards, the sense board and the power stage, with a five-wire link between them. The three projects come from one design file, so they cannot drift apart.

Where it sits

The two boards are in the fuselage, near the pack. Refer to each board page for its position. On CAN bus 2 the node is static node id 20. Its 120 Ω terminator jumper ships open, because the node is mid-bus.

Main parts

Part	Function
STM32F405RGT6	MCU, runs AP_Periph
TJA1051T/3	CAN transceiver
6 x 910 kΩ over 100 kΩ, 0.1 %	Cell tap dividers, ratio 10.1
LT4320, 4 x PSMN7R0-60YS	Ideal-diode bridge: either plate polarity charges
10 A NANO2 fuse	Protects the wiring
2 x SUD50P06-15L	Charge-enable switch, back to back
5 mΩ shunt, INA180A2	Charge current, 0.25 V per A

Connections

Connector	Type	To
J1, J2	JST-GH 4-pin	CAN bus 2 in and out
J3	JST-GH 8-pin	Balance lead and pack thermistor
J4, J5	XT30 pigtail	Charge plate leads, one for each side
J6	XT30 pigtail	Pack tap
J12	USB-C	Bench power and first flash
J14 to J15	GH-5 to PH-5	Link between the two boards

Status

Rev A. The project has a root sheet and four sub-sheets, and ERC is clean. On 2026-09-26 the netlist agreed with the hwdef pin for pin. The two built boards are at rev A rc6, frozen on 2026-09-29.

The first flights do not carry the charge node (2026-10-04), so the first build has no dock charge. The node waits for our own FC with two CAN buses. ArduPilot board id 20401 is not registered.

Schematic and layout

Files

From the EDA repository at revision b201257 (2026-10-12). Open the files in KiCad 10 or later.