Connectors
Every connector adds resistance, mass, and a failure point. Use them where you genuinely need to disconnect; solder the rest.
Power connectors
Section titled “Power connectors”| Connector | Pair mass | Current | Use in insect classes |
|---|---|---|---|
| XT30 | ~2–3 g | ~15 A cont., 30–40 A burst | The default main battery / removable-link connector — good for ~95% of beetleweights |
| XT60 | ~5–6 g | ~30 A cont., 60 A burst | Only if you’ve measured a sustained current that warrants it; uncommon on current beetles |
| XT90 / AS150 | ~12 g+ | 60–90+ A | Hobbyweight and up — wasted grams in insect classes |
| GNB A30 / BT2.0 / red JST | <1 g | ~10–20 A | Drive-motor leads — small and light |
| MR30 / MT30 | ~1.5 g | ~15–30 A | Compact 3-pin option for brushless phase leads |
| 3 / 3.5 mm bullet | ~1.5–2 g | ~25–40 A | Brushless phase leads (3.5 mm ships on most motors but is overkill) |
Use XT30 for the main battery connection in a beetleweight. Weapon spin-up current is brief and the XT30 handles those bursts fine; a full XT60 is a few grams of margin you rarely need. For drive leads, drop to a GNB A30, BT2.0, or red JST. Never run a bigger connector than the leads on your battery.1
Match the connector to the battery lead gauge and the removable-link current. A loose or undersized power connector overheats, sags voltage, and can arc — but so does a needlessly heavy one bolted to thin wire.
Signal connectors
Section titled “Signal connectors”- 0.1” (2.54 mm) servo connectors (JR/Futaba) — receiver to ESC signal. Retain them: a dab of hot glue or a friction lock so a hit doesn’t unseat the signal lead (which triggers failsafe mid-match).
- JST-XH — LiPo balance leads. Never carry discharge current on these.
Solder vs connector
Section titled “Solder vs connector”Solder directly (no connector) at:
- ESC-to-motor on brushed motors,
- distribution/bus joints inside the robot,
- anywhere you won’t routinely separate.
Keep connectors at:
- the battery (you swap and charge it),
- the removable link (required — it’s your safety disconnect),
- brushless phase leads if you need to swap motor direction or service the motor.
Practice
Section titled “Practice”Solder connectors properly — tin both sides, full fillet, no cold joints — and heat-shrink. A high-resistance power connector is a common cause of “weapon won’t spin up” and “ESC keeps cutting out.” Learn to solder well; use leaded solder (easier, and safe if you wash your hands) and a decent iron.1