LiPo Battery Basics — C Rating, Cell Count, and Care
LiPo batteries are the most maintenance-sensitive component in an FPV build. Misuse kills them fast or causes fires.
Cell Voltage
| State | Voltage per cell |
|---|---|
| Fully charged | 4.20 V |
| Nominal | 3.70 V |
| Storage | 3.80–3.85 V |
| Low cutoff | 3.50 V |
| Dead / damaged | < 3.30 V |
Never discharge below 3.5 V per cell under load. Set your FC low-battery warning to trigger at ~3.5–3.6 V per cell (voltage under load, not at rest).
Cell Count
| Config | Nominal | Max | Typical use |
|---|---|---|---|
| 1S | 3.7 V | 4.2 V | Tiny whoops |
| 2S | 7.4 V | 8.4 V | 2.5" micros |
| 3S | 11.1 V | 12.6 V | 3" micros |
| 4S | 14.8 V | 16.8 V | 5" standard |
| 6S | 22.2 V | 25.2 V | 5" high performance, 7"+ |
C Rating
C rating is the discharge rate multiplier relative to capacity.
1Max continuous current (A) = Capacity (Ah) × C rating
Example — 1500 mAh, 100C battery:
1Max current = 1.5 Ah × 100 = 150 A
The C rating is marketing on most budget packs. Treat it as a rough guide. A real-world usable rule:
- 5" freestyle quad: aim for 1500–2200 mAh, 80C+ on 4S
- 5" efficiency: 2200–3000 mAh, 50–80C on 4S or 6S
- Racing: 650–1300 mAh, 100C+ on 4S–6S
If your pack sags heavily under throttle punch (voltage drops 1+ V per cell), C rating is insufficient for your build's current draw.
Storage Charge
Always store LiPo batteries at 3.80–3.85 V per cell. Never store fully charged or fully depleted.
- Fully charged storage accelerates capacity loss and causes puffing.
- Fully depleted storage risks cell damage from continued self-discharge below minimum voltage.
Most chargers have a Storage charge mode — use it if you won't fly within 24–48 hours.
Puffing
A puffed battery has internal gas buildup — a sign of cell damage, usually from overdischarge, overcharge, or high current stress.
- Minor puff: still usable but monitor closely. Retire soon.
- Significant puff: retire immediately. Do not charge.
- Dispose of at an electronics recycling facility — discharge fully in a salt water bucket first.
Safe Handling
- Charge on a LiPo-safe bag or fireproof surface — never unattended.
- Never charge a damaged, puffed, or crashed pack without inspection.
- Charge at 1C as the default (i.e., a 1500 mAh pack → 1.5 A charge rate). Higher rates reduce cycle life.
- Never leave a charging LiPo unattended.
Battery Life
Expect 150–300 cycles from a quality pack if treated well. Indicators of end-of-life:
- Significant capacity loss under load
- Increased internal resistance (measure with your charger)
- Consistent puffing after flights
- Voltage sag exceeds 0.5 V/cell under load at moderate throttle
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