The C-rating on a LiPo pack is one of the most discussed and most misunderstood specifications in FPV.
What C-Rating Actually Means
A 1300mAh pack rated at 100C can theoretically deliver 130A continuously (1.3Ah x 100C). In practice, manufacturer ratings are often optimistic — real sustained output is 50-70% of the label. Peak burst ratings (2x continuous) are achievable for 5-10 seconds.
Internal Resistance: The Real Metric
IR measured in milliohms is the single best indicator of battery health. A fresh 6S 1300mAh pack: 2-5mOhm per cell. Voltage Drop = Current x IR. At 120A with 12mOhm total pack IR, you lose 1.44V — power turning into heat instead of thrust.
IR milestones: under 5mOhm/cell = excellent. 5-10 = normal after 100+ cycles. Above 10 = performance degrades. Above 20 = retire or bench-test only.
Voltage Sag
At full throttle punch-out, a healthy 6S pack sags from 25.2V to ~23.5V. A tired pack with high IR may sag below 22V, triggering OSD warnings and robbing power when you need it most.
Brand Comparison
Tattu R-Line V5 and GNB lead in low IR consistency. CNHL Black offers excellent value for freestyle. Ovonic and Zeee are budget options for cruising. Pay attention to IR, not C-ratings.
