How long the RC lipo battery can last

Many people will be very concerned about how long the RC model battery can be used, and the service life of these issues. Here, we will briefly talk about it.

First we need to understand the battery capacity

The battery capacity is measured in ampere hours or milliampere hours. It can indicate the total power that the battery can store. Generally, the higher the capacity, the longer the battery life.

By analogy with a gas storage tank, a high-capacity battery has a large gas storage tank that can store a large amount of gas.

The best way to understand lipo capacity is to consider how to measure lipos. The general procedure is to take out the battery and find out what causes the constant current to fall below the battery cut-off voltage within 1 hour.

In this way, the capacity is 1 hour of the current time.

Therefore, if you discharge a 3s 3000 mA (3 Amps), the 3000 mAh battery will fall from full voltage to cut-off voltage within 1 hour. 3 amps x 1 hour = 3 amp hours = 3000 mAh.

One thing you need to pay attention to ...

The capacity of the battery decreases with increasing current consumption. This means that if the constant 3 Amp current consumption is 3000 mAh, then if the constant 6 Amps or constant 30 Amps current will be less than 3000 mAh.

I have seen a lot of explanations about capacity, but I have not told you this. You will often see it written, if your battery capacity is 3000 mAh, it means that you can consume 3 amps in 1 hour, 6 amps in 30 minutes, or 30 amps in 6 minutes. This is usually not the case.

To illustrate how current affects capacity, you need to look at the discharge curve of a lithium battery. Most good battery data sheets will show different discharge curves for different constant current consumption. For example, see the figure below

 The figure shows the discharge curve of 1S, 21000 mAh, 8C battery. Each line represents a different constant current. The graph shows us that for a given cut-off voltage, the discharge capacity will decrease as the current consumption increases.

In this example, for a cut-off voltage of 3.0 V, the capacity at 10.5 A (0.5C) is 22000 mAh, and the estimated capacity at 105 A (5 C) is also about 22000mAh, but at 168 A (8C) 21000 mAh.

Therefore, two things to remember about capacity are:

The capacity tells you that the battery can provide 1 hour of current

If the battery is discharged with a current higher than this current, the capacity will decrease.

(Note that ampere hours are not a measure of energy. Energy is measured in watt hours. If you assume that the battery is discharged at a constant voltage, you can calculate energy accordingly. However, as we learned in the previous section , The battery cannot be discharged at a constant voltage.)

Next, we have to care about the service life of the battery

When you use the battery to charge and discharge, its capacity will slowly decrease. Therefore, if your battery is 1300 mAh out of the box, after 200 charge / discharge cycles, the battery charge may drop to 75% (about 1000 mAh). LiPo may last between 300 and 500 cycles, depending on how it is maintained.

What should you do to maximize battery life?

You can do many things.

*First, an appropriate charging voltage must be used.

The charging voltage of each battery must not exceed 4.2V.

*Second, do not over-discharge the battery.

*Third, never fully charge the battery. The recommended storage voltage is 3.8 V to 3.85V. Most chargers allow you to set it to store charge.

*Fourth, use balance charges.

Do all these things and your battery will last more charge / discharge cycles.