3s vs 4s lipo battery, which one should be chosen

First of all, what is 2s, 3s, 4s…

Let’s start with the most essential difference. Simply put, they are all multiples of a single lithium polymer battery, and they are connected together to form a higher voltage battery. If two batteries or batteries are connected in series, the voltage will increase; 2S battery means that there are two cells lipo battery in this battery, the lipo battery of one cell is 3.7V, so the battery voltage of 2S is 7.4V, the same as the battery voltage of 3S It is 11.1V, 4s voltage is 14.8v.

2s, 3s, 4s difference

For example, is the difference between 2s 5000mah, 3s 5000mah, and 4s 5000mah just voltage? And will the use time be the same?

*Battery power problem

If you use 4s instead of 3s batteries, the voltage is higher and the current is lower, but for the same load, the power is the same. Power = voltage * current, so lower current does not mean lower power. If you have a 300-watt electric motor and use a 3s battery, it will consume 27 amps of current, then if you switch to a 4s battery, it will consume 20.3 amps of current, which is not consuming less energy or power. This is the same 11.1v * 27amp = 300watts and 14.8v * 20.3amps = 300watts.

* Correspondence between voltage and motor

When the applied voltage is higher, the motor can rotate faster. The RPM (rotation per minute) of the motor under no load depends on the KV value of the motor – RPM = voltage x KV.

Suppose our FPV quad has a 2300KV motor. When powered by a fully charged 3S lipid (11.1V), the theoretical RPM is 2300 x 11.1 = 25530. This means that the motor rotates about 25,530 times per minute without any propeller. When using 4S lipid (14.8V) to power the same motor, the RPM is 2300 x 14.8 = 34040, and you can see the RPM increases significantly.

The increase in RPM means that the electric motor can generate more thrust, more power, faster flight speed and agility. But the throttle lever has also become more sensitive and more difficult to control.

Please note that due to the increased weight of the voltage regulator, battery, etc., the 4S setting is usually slightly heavier than the 3S.

*Choose 3s or 4s

If you choose RTR/RTF, please choose according to the model manufacturer, if you are kits, then you need to choose according to the motor KV value and ESC parameters.

fpv batteries

*What should I pay attention to in use?

To protect your LiPo, you usually do not want to consume more than 80% of its capacity in any use. In our example, you do not want to use more than 5000 x 0.8 = 4000 mA or 11.1v x 4amps = 44.4 watts. If the battery charge falls below this level, the battery may be damaged. You can understand the battery status by monitoring the voltage during the process. When you use the energy in the battery, the voltage will drop. In the case of the RC plane, many flight controllers have built-in alarms. You can program the alarm to notify you when the battery voltage is below a preset point and tell you that you should land as soon as possible. If lipo batteries are overcharged or damaged, they may explode and catch fire. One sign of overcharging is when you see the battery “swell” or change its thickness.

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