Before we dive into this article, I need to address something upfront—we recently tested a Zeee battery pack, and the response was, well, mixed. While Zeee clearly has a strong fan base, many viewers didn’t agree with the results of that test. Some even questioned whether the data truly reflected the battery’s performance. So, after going back to the drawing board (and the budget), I decided to retest a fresh set of batteries to give this another shot.
That brings us to today’s article. When choosing a battery for your RC vehicle, one of the most talked-about specs is the C rating. But what does it actually mean? And how do you know if it’s telling the truth about a battery’s capabilities? In this article, we’ll break down the idea of a “true C rating” by putting the Zeee 5200mAh 120C LiPo pack through a full performance test. Along the way, we’ll explore not just what the numbers say on paper, but how the battery really performs under load—and what that means for you.
What is the C Rating?
The C rating of a battery essentially represents how much current a battery can safely discharge relative to its capacity. For example, a 120C-rated battery with a capacity of 5200mAh can theoretically deliver a peak current of 624A (120 * 5.2). However, the “true C rating” is determined through rigorous testing. We expect the manufacture to do this accurately and market the batteries accordingly and truthfully. Unfortunately this does not happen. Let’s explore further.
The Zeee 5200mAh 120C LiPo Battery: A Quick Overview
This 4S LiPo battery has a nominal voltage of 14.8V. It comes in a durable hard case for protection. It features a balance tap with a convenient plastic cover that makes connecting the battery easier, which is a small but useful detail. What sets this battery apart is its claimed C rating of 120C (624A), which suggests it should be capable of handling high current loads. However, as we’ll see, the true performance can differ.
Testing Methodology
We tested the Zeee battery using three main methods: a 105A load test, a C rating test, and an internal resistance test. Each test focused on a different aspect of the battery’s true C rating.
- 105A Load Test: In this test, the battery was loaded at a constant 105A to see how it performed under high discharge conditions. The battery’s voltage was monitored as it sagged under load, and the current followed this decrease, which is typical of most batteries as they begin to run out of charge. The goal was to measure how long the battery could maintain high current output before reaching a low voltage cutoff.
- Ultimate C Rating Test: This test aimed to push the battery to its thermal limits by gradually decreasing the current after each test while monitoring temperature. Current is held constant during the duration of the test. The test was stopped if the temperature exceeded 58°C, which is considered the upper limit for safe operation. Ultimately, the aim is to determine how much current the battery can deliver while maintaining safe operating temperatures.
- Internal Resistance Test: By measuring the internal resistance of the battery, an estimated C rating can be calculated. A higher internal resistance indicates higher energy losses within the battery, reducing its efficiency and performance under load. This test helps estimate the battery’s true C rating by evaluating how it could behave under realistic conditions.
The Results: Breaking Down the True C Rating
Test 1: 105A Load Test
The 105A test results showed that the Zeee battery performed similar to the last test, with the voltage sagging in a predictable manner as the load increased. The key observation here was the voltage drop and how quickly the battery approached the low voltage cutoff. The test revealed that while the battery could maintain 105A for a short duration, its performance would drop significantly as the voltage sagged. This is important because it highlights that while the battery is rated for a high C value, its practical performance under high loads does not align with the theoretical ratings. In the below image you can see the results of each of the 4 4s 5200mAh Zeee batteries that we tested.
Test 2: Ultimate C Rating Test
In the ultimate C rating test, the results did not improve—in fact, the Zeee batteries once again showed significant underperformance. During an 80A discharge, temperatures rose rapidly, exceeding the safe limit of 58°C. Reducing the load to 70A produced the same result, with temperatures still surpassing the safety threshold. Even at 65A, there was some improvement, but the battery continued to exceed the maximum safe temperature. At 60A, the battery delivered its best performance. However, it still exceeded 58°C in the final seconds—another failure. Based on this, the battery’s effective C rating appears to be just under 12C, with a continuous discharge capability closer to 57–58A. These are some wild results and the lowest values ever tested for a battery greater than 5000mAh.
Test 3: Internal Resistance Test
The internal resistance test offered a final piece of insight into the Zeee battery’s capabilities. Measurements taken across multiple cells revealed relatively high resistance levels—an indicator that the battery struggles to deliver high current efficiently. Averaging the internal resistance across all 8 cells from the two new Zeee packs resulted in a value of 7.55 mΩ. We then used this figure to estimate the battery’s true C rating, which closely aligned with the results from the previous performance tests. You can do the same thing at home using the calculator found on my Patron site which is downloadable if you become a member. Based on internal resistance, the calculated maximum continuous discharge current was 66A—remarkably close to the real-world limit observed during testing, which was just under 60A.
The Takeaway: Why the “True C Rating” Matters
The “true C rating” is crucial for users who want to ensure that their battery can handle the demands of their RC applications. Manufacturers often claim high C ratings for their products, but they sometimes inflate these numbers, which don’t reflect real-world performance. Through testing, we’ve shown that the Zeee 5200mAh 120C battery, while advertised as a 120C pack, realistically performs more like a 60C battery.
If you’re looking for a battery that can deliver high currents over longer periods without overheating, understanding the true C rating is essential. This ensures that you choose a battery that can handle the loads of your RC vehicle without compromising on safety or performance.
By conducting tests like these, RC enthusiasts can make more informed decisions about which batteries to use, ensuring they get the performance they expect from their gear.
Conclusion
The Zeee 5200mAh 120C battery test illustrates an important point: While marketing labels may claim high performance, real-world tests often reveal a different story. The true C rating helps you better understand the limits of your battery, ensuring you get the best performance possible for your RC applications. Whether you’re racing, bashing, or flying, knowing your battery’s true capabilities can make all the difference in achieving optimal performance.