Spektrum Batteries 7.4 V (2S)

Spektrum 7.4 V (2S) Batteries — What They Are

Spektrum 2S LiPo packs (7.4 V nominal, 8.4 V fully charged) provide dependable power with low weight and manageable heat. They are available in Smart and Smart G2 versions with IC3/IC5 connectors for easy, data-enabled charging and cleaner installs.

When to Choose 2S

• Use if you run 1/10 touring, stadium/short-course trucks, drift, or crawlers where smooth throttle and cooler temps matter.
• Use for trainer planes and park flyers that specify 2S for longer flights and milder power.
• Avoid for heavy 1/8-scale models or high-speed bashing that benefit from 3S–6S voltage.

Smart vs. Smart G2 Compatibility

• Smart (G1) packs: Include a balance lead. Can be balance charged on most LiPo chargers (with appropriate IC/EC adapter) or on a Spektrum Smart charger for auto-detection and pack data.
• Smart G2 packs: No separate balance lead; balancing is handled through the IC connector and require a Spektrum Smart charger for proper balance charging.
• Connectors: IC3/IC5 are backward compatible with EC3/EC5 (signal pin is unused). Match the connector to your ESC and current needs.

How to Choose a 2S Pack

1. Capacity (mAh): More mAh = longer runtime and more weight. Typical picks:
   • 1/10 track/basher: 5000–6500 mAh
   • Crawlers: 2200–5000 mAh (favor lower weight)
   • Trainers/park flyers: 1500–3000 mAh
2. Discharge rating (C): Higher C handles higher current and reduces voltage sag but may add cost/weight. For 1/10 cars, 50–100C is common; crawlers 30–60C; small planes 30–50C.
3. Case: Hard-case for cars/trucks where impacts and chassis edges are common. Soft-case for aircraft and lightweight builds.
4. Connector: IC3 for lighter setups; IC5 for higher current and lower resistance. Avoid adapters when possible.
5. Fit: Confirm tray space (length × width × height) and strap location. Many 5000–6000 mAh hard-cases are ~135 × 47 × 25 mm; check your model’s spec.

Quick Selector (Typical Use)

Charging and Care

• Charge rate: Default to 1C (e.g., 5000 mAh → 5.0 A) unless the pack explicitly supports higher.
• Balance charge every time. Smart chargers handle this automatically; G2 requires a Smart charger.
• Storage voltage: 3.75–3.85 V per cell; store cool and dry.
• Low-voltage cutoff: Set ESC LVC around 3.2–3.4 V per cell under load to protect cycle life.
• Thermal care: Let packs cool to ambient before recharging. Stop using any pack that swells, leaks, or has damaged leads.

Runtime Estimator

Estimated minutes ≈ (Capacity in mAh ÷ 1000 ÷ Average current in A) × 60

• Example car: 5000 mAh at 20 A avg → ~15 minutes.
• Example crawler: 2200 mAh at 6 A avg → ~22 minutes.
• Example trainer: 2200 mAh at 8 A avg → ~16 minutes.

Troubleshooting

• Short runtime: Verify full charge, check drivetrain drag and tire choice, and confirm ESC LVC isn’t set too high.
• Voltage sag: Inspect connectors for wear, consider a higher C rating, or reduce gearing/timing.
• High temps: Gear down 1–2 teeth on pinion, improve airflow, and avoid back-to-back hot charges.
• Charger won’t balance: If using a Smart G2 pack, you must use a Spektrum Smart charger.

Alternatives

• 3S (11.1 V): More speed/power for compatible setups; increases heat and drivetrain load.
• NiMH: Simpler handling for beginners, but heavier with lower performance and no pack data.

FAQ

Is 2S enough for 1/10 racing?

Yes. Many 1/10 classes mandate 2S. Fast lap times come from consistency, temps, and gearing.

Do I need a Spektrum Smart charger?

Highly recommended for Smart packs and required for Smart G2 (no balance lead). It auto-detects cell count and manages balancing and storage modes.

Can I use IC3 with an EC3 ESC?

Yes. IC3 is backward compatible with EC3. The signal pin remains unused.

Hard-case or soft-case for crawlers?

Soft-cases save weight and fit tight trays; choose hard-case if your battery area has sharp edges or sees impacts.

What LVC should I run?

Start around 3.2–3.4 V per cell under load. If you see premature cutoffs, check gearing and pack health before lowering further.