Do you know if your drone battery can handle the current your motors demand during a full-throttle climb? Ignoring the "C-rating" on your label is the fastest way to destroy your battery or crash your aircraft.
"45C" indicates the battery's maximum safe continuous discharge rate relative to its capacity. It means the battery can deliver a current output equal to 45 times its capacity without overheating. For example, a 5000mAh battery rated at 45C can provide a continuous 225 Amps to your drone's motors.
As a manufacturer at KKLIPO, I see many procurement managers focus solely on capacity (mAh) and ignore the discharge rate (C). This is a mistake. The C-rating defines the "muscle" of the battery. If capacity is the size of the fuel tank, the C-rating is the width of the fuel line. For clients like Omar operating in harsh conditions, understanding this number is the difference between a successful mission and a battery fire. Let’s break down exactly how to read and use this number.
How do you calculate the actual Amperage output?
The number "45" is just a multiplier; it tells you nothing about the actual power until you do the math with the capacity.
To find the maximum continuous current (Amps), convert the battery capacity to Amp-hours (Ah) and multiply it by 45. For a standard 2200mAh (2.2Ah) battery, the calculation is 2.2 × 45 = 99 Amps. This is the limit your power system must stay under.
I often see confusion here. A client will ask, "Is a 45C battery powerful enough?" My answer is always, "Which one?" A tiny 45C battery for a micro-drone might only output 20 Amps. A massive 45C battery for an agricultural drone might output 400 Amps. The C-rating scales with size.
Let's look at a practical example from our factory floor. We produce a popular 2200mAh 4S pack for FPV racers.
- Step 1: Convert capacity. 2200mAh ÷ 1000 = 2.2Ah.
- Step 2: Multiply by C-rating. 2.2Ah × 45 = 99 Amps.
This means your Electronic Speed Controller (ESC) and motor combination must draw less than 99 Amps at full throttle. If your drone pulls 120 Amps, this "99A limit" battery will overheat instantly. The voltage will drop (sag), and the drone will feel weak.
Now, consider a larger industrial battery we ship to the Middle East: 16,000mAh (16Ah).
- Calculation: 16Ah × 45 = 720 Amps. That is a massive amount of power, capable of lifting heavy cinema cameras or LIDAR sensors. Even though both batteries are "45C," their performance is completely different.
What is the difference between continuous and burst ratings?
You will often see two numbers on a label, such as "45C/90C," and it is vital to know which one to trust for your flight planning.
The first number (45C) is the continuous rate the battery can handle for the full flight. The second number (90C) is the "burst" rate, which is the maximum current available for short pulses—typically less than 10 seconds—during rapid acceleration or emergency maneuvers.
In the lab, we test these limits destructively so you don't have to. The "Burst" rating is dangerous if misunderstood. Think of 45C as your cruising speed. You can fly at this level until the battery is empty without damaging the chemistry. Think of 90C (the burst) as a sprint. If you sprint for 100 meters, you are fine. If you try to sprint a marathon, you will collapse.
For a 2200mAh battery:
- Continuous (45C): 99 Amps.
- Burst (90C): 198 Amps.
Why does this matter for a procurement manager like Omar? If you are designing a drone that hovers steadily (like a surveillance drone), you only care about the continuous rating. However, if you are flying an FPV racing drone or a heavy-lifter that needs to arrest a fast descent, you rely on that Burst rating. But be careful. Manufacturers define "Burst" differently. For some, it is 10 seconds. For others, it is 3 seconds. Using the burst current for too long causes the internal temperature to spike. This leads to "puffing" (gas generation inside the pouch) and permanent damage. Always size your battery based on the Continuous 45C rating to leave a safety margin.
| Rating Type | Multiplier | Calculated Amps (2.2Ah) | Safe Duration |
|---|---|---|---|
| Continuous | 45C | 99 A | Full Flight |
| Burst | 90C | 198 A | < 10 Seconds |
| Charging | 1C - 2C | 2.2 A - 4.4 A | Until Full |
Why is a 45C rating critical for performance and safety?
Choosing a lower C-rating might save weight or money, but it creates a hidden bottleneck in your drone's power system.
A true 45C battery has lower internal resistance, meaning it delivers power more efficiently with less voltage sag. If you use a battery with a C-rating that is too low for your motors, the battery will struggle to deliver current, causing it to generate excessive heat and potentially catch fire.
This is the most important section for safety. When a motor asks for current, the battery tries to provide it. If you have a 45C battery, the "pipe" is wide. The current flows easily. The battery stays cool, and the voltage stays high. This gives your drone a "locked-in" feel and punchy acceleration.
If you use a low-rated battery (e.g., 20C) for a high-power application:
- Voltage Sag: The internal resistance blocks the flow. The voltage drops instantly when you punch the throttle. Your telemetry might scream "Low Battery" even if you just took off.
- Heat: The energy that cannot get out turns into heat inside the pack. In the 40°C heat of a Dubai summer, a battery that is already struggling internally will cross the thermal runaway threshold very quickly.
- Puffing: The electrolyte boils and creates gas. The battery swells up. Once a battery is puffed, it is a ticking time bomb and must be disposed of.
However, do not confuse Discharge C-rating with Charge C-rating. I have seen clients ruin a 45C battery by trying to charge it at 45C.
- Discharge: 45C (99 Amps) -> OK.
- Charge: Usually 1C to 2C (2.2 to 4.4 Amps). Never charge at the discharge rate.
Summary: 45C isn't just a performance number; it is a safety rating. It ensures your power system runs cool and your voltage stays stable under load.
Conclusion
"45C" means the battery can safely continuously discharge 45 times its capacity in amps. It ensures high power output, reduced voltage sag, and cooler operation for demanding drone flights.