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5 Ways to Check the Capacity of Lipo Battery

One common challenge faced by RC hobby enthusiasts is determining how to check the capacity of Lithium Polymer (LiPo) batteries. In this article, we delve into five prevalent and effective methods for such checks. For those simply wishing to verify if their battery’s milliampere-hour (mAh) aligns with its rated capacity, three methods – using a battery charger, discharger, and checker – are generally sufficient. However, due to technological disparities across different manufacturers, the precision of these methods can vary. This article will thoroughly examine each method, discussing their advantages and drawbacks, to assist readers in more accurately understanding and assessing the performance of their batteries.

Five Ways of Checking

Battery Charger

Nowadays, most RC chargers show how much mAh has been charged into the battery during charging, making it possible to gauge the actual capacity of the battery. Take, for instance, a standard LiPo battery: when charged from a low voltage of 3.2V up to its full charge voltage of 4.2V, the total mAh displayed on the charger is very close to the real figure.

Battery Discharger

Battery Dischargers show the mAh discharged during the process, enabling you to set a specific cut-off voltage and discharge current for testing the battery’s true capacity. For instance, by setting the cut-off voltage to 3.2V and the discharge current to 10A, the discharger will continuously discharge at 10A until the battery hits 3.2V, showing you its real capacity. Some advanced dischargers, like SkyRC’s BD250 and AD350, come with basic battery analysis functions. They are more accurate than regular dischargers and chargers, giving detailed insights into the battery’s capacity, discharge patterns, voltage, and more.

Battery Checker

Some smart LiPo battery checkers quickly provide data like the battery’s mAh, charge percentage, voltage, etc. Just by connecting the battery to these checkers, you can browse through this information. It’s important to note that some of these checkers might not be able to read the mAh of batteries from other brands, such as the Spektrum checker.

Battery Analyzer&Tester

Pro-grade Battery Analyzers and testers tend to be pricey and are usually seen in labs for specific experimental work. They offer the most accurate mAh readings for batteries. But for everyday RC hobbyists like us, we don’t really need to go to these lengths to measure our battery’s mAh. It’s enough just to know about them.

Flight/Running Time

Indeed, we can get a rough idea of a battery’s performance by looking at the flight times of drones and the running times of RC models. This method doesn’t give exact mAh numbers, but it does give a rough indication of the battery’s capacity. For example, by comparing the flight or running times of two identical-spec LiPo batteries, we can figure out if a battery is living up to its rated mAh.


In summary, choosing the right method to check the capacity of your LiPo batteries is crucial for both performance and longevity. For most RC hobby enthusiasts, using a standard battery charger, discharger, or smart battery checker will suffice. These tools offer a good balance between accuracy and affordability. However, for those requiring more precision, professional battery analyzers and testers provide the most accurate readings but at a higher cost and are typically more suited for lab environments.

It’s important to remember that while assessing battery capacity, maintaining the health of your LiPo batteries is paramount. Always avoid over-discharging your batteries, as this can lead to swelling and irreversible damage. A safe cut-off voltage range to consider is between 3.2V to 3.5V. Setting your equipment to respect these limits will help in prolonging the life of your batteries, ensuring they deliver the performance you expect while keeping them in good condition. Making informed decisions based on these guidelines will help you to effectively manage and maintain your LiPo batteries, ensuring their optimum performance and durability in your RC hobbies.

What You Need to Know

Over time, the performance of batteries naturally diminishes, leading to a reduction in their capacity. This degradation is an inherent characteristic of all batteries, including LiPo batteries, and is influenced by factors such as charging cycles, usage patterns, and general wear and tear.

Another important aspect to consider is voltage rebound after discharging. Batteries, especially when subjected to high-current discharge, exhibit a phenomenon where their voltage slightly recovers or “rebounds” after the discharge process is halted. This voltage rebound can impact the accuracy of measuring a battery’s mAh capacity. The higher the discharge rate, the more significant the voltage rebound tends to be, which can lead to overestimations of the battery’s remaining capacity.

In the market, it’s not uncommon to encounter overrated specifications for LiPo batteries. Just like the advertised ‘C’ rate (a measure of the discharge rate relative to the battery’s capacity), the actual capacity of many LiPo batteries often falls short of what is claimed in marketing materials. While this is a widespread issue, the extent of overrating varies. Higher-quality batteries generally come closer to meeting their advertised specifications. It’s important for consumers to be aware of these discrepancies and understand that these figures can sometimes be more of a marketing strategy than an accurate representation of the battery’s capabilities. When selecting LiPo batteries, it’s wise to consider reviews, brand reputation, and empirical testing data to make an informed choice.

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