Daisy chaining power and using a 5A 12V power supply seems insufficient for full utilization #132
Description
When the SO-ARM100 is built with STS/Feetech ST3215 (30 kg·cm, 12 V) servos, the current guidance of using a 12 V / 5 A PSU and daisy-chaining power through the 3-pin jumpers seems insufficient for full-load use. Under realistic heavy moves (multiple joints accelerating or holding near stall), the bus can brown-out and the first few jumpers/connectors in the chain are forced to carry the downstream current, which exceeds their safe rating.
Evidence / Calculations
ST3215 key specs (12 V setup):
Stall current ≈ 2.7 A per servo
No-load current ≈ 0.18 A per servo
Torque constant ≈ 11 kg·cm/A
Daisy-chaining power through small 3-pin cables concentrates the sum current into the first link(s). Typical connectors/wires in these jumpers are ~2–3 A/pin and ~AWG 26–24; forcing 8–16 A through any one segment risks **overheating, voltage drop, and resets.
Impact Observed / Likely
Voltage sag / brown-outs** during simultaneous joint motion or when holding load at reach
Servo resets / misposition** under acceleration
Hot jumpers/connectors** at the start of the chain
Limits on achievable speed/accel/payload compared with the mechanical capability