The Markings and meanings on LiPo Batteries
The markings on LiPo batteries give many people headache. In this article, we’ll discuss what you’ll need to know about the markings when you’re buying LiPo batteries.
Let’s use a 7.4v 7200 mAh battery as an example. The marking on it says 70C-7200-2s1p
-70C-
This marking indicates the discharge current stated with a C rating, where 1C equals to the nominal current. So, in a 7200mAh battery 1C equals to 7,2A which equals to 70C = 70*7,2=504A. This means that the maximum discharge rate is 504A. C rate indicates the maximum discharge current of a battery. This should match the amount of current your car draws. C-rate doesn’t determine the maximum speed of your car, but it impacts the throttle response. If the C rate is too low, it might result in a rubber band-like throttle response. When choosing batteries for your car, it’s better to get batteries with a higher C rating because a C rating that does not meet the current requirements of your vehicle might damage the batteries. You can tell your batteries’ C rating is too low if the batteries warm up way over body temperature. The speed controller also warms up more when using batteries with lower discharge rates.
-7200mAh-
This indicates the battery’s capacity, in other words, how much power is available. This directly impacts the run time of your vehicle. The greater the capacity, the more you’ve got run time. Typically, the batteries’ capacity is between 4000 and 6000mAh. A battery with a greater capacity can discharge more power than a battery with a smaller capacity. For example, the current output of a 4000mAh battery with a 25C rating is 100A whereas that of a 5000mAh battery is 125A.
-2s1p-
This indicates the internal configuration of the battery. 2S means that the battery has two cells in series to get a voltage of 7.4v. 1P means that the cells have not been wired in parallel but both cells have the nominal capacity, in this case 7200mAh. 2s2P means that there are two cells wired in series and two in parallel with them. Each cell has the capacity of 3600mAh/cell.
-HardCase-
This marking means that the battery has a hard casing.We strongly recommend to use hardcase batteries in RC-cars.
The markings after the information on the cells (e.g., 2S1P) can vary depending on the manufacturer. Depending on the brand, the markings at the end might tell you information such as which model series the battery belongs to or what type the casing is. It’s important to choose batteries that best suit their purpose.
How the used voltage affects current
Remember that the more there are cells in the batteries, i.e. the higher the voltage is, the smaller the amount of current. A high C rating means a more vigorous current output, but the C rating does not have to be as high when driving with 3S batteries (11.1v) and 2S (7.4v). I’ll explain this using an example. If the engine is 700W and you’re using a 2S battery with 7.4v voltage, the total current is 700/7.4=94.6A. When the voltage is increased to 3S, i.e. 11.1v, the current is 700/11.1v=63.1A. The less there is voltage in use, the higher the current (A). The greater the A, the more the components will warm up. Please note, however, that the voltage cannot be increased arbitrarily, but you need consider the technical restrictions of the rest of your components. If the electronic components can handle an increase in voltage, you need to switch to a smaller pinion gear in the motor to avoid over-gearing (and overheating) resulting from the increased speed of rotation caused by the increased voltage.
This is why high-quality batteries can handle demanding use better. When the current output is a decent 60–100C, the voltage won’t dip during acceleration. This means that the amount of needed current (A amperes) is smaller and the electric components warm up less because the voltage remains the same during the whole run.
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