Flip over any FPV LiPo battery and you'll see a big number: 100C, 120C, 150C, even 200C.
The implication is clear: higher C-rating means more power, better punch, faster acceleration. Right?
Not exactly.
C-rating is one of the most misunderstood—and most inflated—specs in the entire FPV hobby. In this guide, we'll break down what C-rating actually means, why you can't always trust the label, and what actually matters when you're choosing batteries.
What C-Rating Actually Means
C-rating indicates the maximum continuous discharge rate of a battery, relative to its capacity.
The formula is simple:
Max Continuous Amps = Capacity (Ah) × C-Rating
Example:
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A 1300mAh (1.3Ah) battery rated at 100C can theoretically output:
1.3 × 100 = 130 amps -
The same battery at 150C claims:
1.3 × 150 = 195 amps
In theory, higher C = more current available. In practice, things are messier.
The Inflation Problem
Here's the uncomfortable truth: C-ratings are largely unregulated.
There's no standardized testing body verifying that a "150C" battery actually delivers 150C. Manufacturers can print whatever number they think will sell.
In independent testing, batteries claiming 100C+ often deliver significantly less. Some "150C" packs have been measured delivering closer to 25–30C continuous under real load.
Why manufacturers inflate C-ratings:
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Marketing—bigger numbers sell better
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Ambiguity—"C-rating" can mean burst or continuous, depending on who you ask
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Lack of enforcement—no one is checking
What Actually Matters for FPV
1. Voltage Sag
This is the real-world metric that matters.
When you punch the throttle, voltage drops. A good battery sags less. A bad battery sags more.
| Battery Quality | Voltage Sag Under Load |
|---|---|
| High quality | 0.3–0.5V drop from resting |
| Average | 0.5–0.8V drop |
| Poor quality | 1.0V+ drop |
Voltage sag directly affects performance. Less sag = more consistent power = better flying experience.
2. Internal Resistance (IR)
IR is the battery's resistance to current flow. Lower IR = less heat, less sag, more efficiency.
Most decent chargers can measure IR per cell. If your cells have high IR, the battery is aging or low quality.
3. Actual Discharge Curves
Independent testing (like the work done by battery testers in the FPV community) shows real discharge curves under load. A "100C" battery that delivers 30C continuous with minimal sag is better than a "150C" battery that sags 1.5V under the same load.
4. Weight
Higher C-rating often means more material (thicker plates, heavier casing). A heavier battery hurts flight performance. Sometimes a lighter 100C pack outperforms a heavier 150C pack.
5. Price vs. Performance
A premium battery might cost 2x more but deliver 20% better performance. Is that worth it? Depends on your flying style.
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Racers: Yes, every advantage matters
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Freestyle: Maybe, if you notice the difference
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Cruisers: Probably not, a good mid-range battery is fine
How to Choose a Battery (Beyond C-Rating)
1. Look for Reputable Brands
Brands with a track record of honest ratings are worth the premium. Community-tested brands are safer bets than unknown labels.
2. Check Independent Test Data
FPV communities often publish battery test results. Look for discharge curves, voltage sag data, and IR measurements.
3. Match to Your Flying Style
| Flying Style | Recommended C-Rating |
|---|---|
| Racing | 100C+ (tested, reputable brand) |
| Freestyle | 80–100C |
| Long-range | 50–80C (weight matters more) |
| Cinematic | 50C+ (smooth flying doesn't need max power) |
4. Consider Weight
A 1300mAh 100C pack might weigh less than a 1500mAh 150C pack and deliver similar performance. Lighter is often better.
5. Test for Yourself
The best test is your own experience. Buy one pack from a new brand, fly it, check voltage sag, and compare to your known-good batteries.
The "Burst" vs. "Continuous" Confusion
Some batteries list two C-ratings:
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Continuous – sustained discharge (what actually matters)
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Burst – short-term peak (marketing number)
If a battery says "100C burst / 50C continuous," the 50C number is what you should care about.
The CaptainRC Perspective
We test every battery we sell. We don't print inflated numbers. What you see on our labels is what the battery actually delivers.
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Racers: Our high-C packs deliver real punch with low sag
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Freestyle: Our mid-range packs balance weight and performance
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Long-range: Our lightweight packs prioritize endurance over raw C
Don't trust the label. Trust the data. And trust the brand that stands behind it.
What battery do you trust? Let us know—we're always curious what works for our customers.