How To Choose The Right Batteries For Your Device?

por phoebe guo en May 07, 2018

Due to the variety of e-cig batteries,  it’s a bit difficult for newcomers to choose. Someone will say that the battery with high discharge performance is the best choice. Of course,the discharge capacity and  storage capacity are the two important reference indicators of batteries which are considered commonly. However, these two parameters are inversely proportional - the greater the storage capacity is, the lower the  is, and the stronger the discharge capacity is, the lower the storage capacity is.

So how should we do? how to choose the right e cig battery according to our own equipment? Today we will talk about it.

Usually the voltage of 18650 battery is 4.2V when fully charged, and its stable voltage is 3.7V,and there are some special materials such as lithium iron phosphate battery of which voltage is 3.2V. The voltage applied to the atomizer when using the mechanical rod is the voltage of the battery itself, unlike the voltage regulating device, the output voltage can be adjusted.

As I mentioned before,the two important indicators of the batteries are discharge capacity and storage capacity. And the discharge capacity of the battery is usually based on the current unit "A". but the parameters of the battery are not marked with "A" when purchasing the battery. What you find is the value of "C".

In fact, in the battery industry, the battery performance is usually expressed by “C”, not “A”, what is “C”? “C” refers to the discharge rate, which is the battery capacity and discharge flow rate. That is: charge/discharge rate = current/rated capacity.

For example, when a battery with a rated capacity of 1000 Ah is discharged at 20 A, its discharge rate is 2 C, and it can be discharged at 20 times its own capacity (1 A).

Battery discharge rates such as 1C, 2C, 0.2C represent the discharge rate of the battery, indicating the speed of discharge. If the capacity will be completely discharged in 1 hour, we called 1C discharge; 5 hours is completed, it is called 1/5 = 0.2C discharge. The battery capacity can generally be detected by different discharge currents. For the 2400mah battery, the 2C discharge current is 48A and the 0.5C discharge current is 12A.

First, how select the right battery for the mechanical rod

The mechanical rod is actually the container of the battery and the conductor of the current and can directly exert the maximum output capacity of the battery, so the requirements for the battery are higher.


With regard to mechanical rods, the point most concerned about is safety. Why do mechanical accidents happen? There are several reasons:

1. Low quality battery without pressure relief valve.

2. The maximum output current is too low, but it exceeds the standard when in use, resulting in excessive battery pressure and serious damage of the battery shell. In fact, due to there is no pressure relief valve, so the battery will not automatically stop working.

3. If the battery breaks and causes the battery to short-circuit or contact with the shaft directly,forming a circuit without passing the switch, the atomizer will automatically work. If the battery is not found for a long time, an accident will occur.

4. Some mechanical rod structural defects or unreasonable design can also lead to battery short circuit.

5. The atomizer electrode structure causes short circuit. (For example, a atomizer with a positive or partially concave power supply and a mechanical rod without a positive post)

Which kind of battery should you use? We can calculate it according to the formula: voltage / resistance = current, so if you use 0.2Ω data, then it is 3.7/0.2=18.5A; if you use about 0.12Ω daily data, then it is 3.7/0.12=30.8A , but the maximum output current of genuine Sony C4 battery is stable at 30A, so 30.8A has slightly exceeded ( because 30A is a steady continuous discharge current, so a short time to reach 40A is possible, but will affect Battery life, and the increase in battery internal resistance are also likely to cause safety problems, so it is not recommended that the resistance is less than 0.12Ω).

The output of the mechanical rod is related to the resistance value. We calculate it by another formula, voltage² / resistance = power, then 0.2 Ω resistance represents (3.7 * 3.7) / 0.2 = 68.45 W, and 0.14 Ω is 97.78W, we can determine how much resistance data to use based on our own needs for clouds. After determining the resistance we need, we can use this resistance to select the battery. Since the capacity is inversely proportional to the maximum continuous output current, the Low-volume, high-capacity batteries can be used when you do not need much clouds.

Second, how to choose the right battery for the voltage regulator equipment?

Voltage regulator equipments have a chip to regulate the output voltage and current, but also with perfect protection measures, so the battery requirements are lower than that of the mechanical rod. But it does not mean that any battery can be chosen casually. After all, energy is conserved.

A lot of players have encountered this situation, that is, once you start to fire, the battery power level will drop sharply , but when the ignition key is released, the power is back. Why?

In fact, although the battery has a nominal voltage, but the output voltage is not always 3.7V, the process of discharge is actually the process of gradually decreasing the battery voltage. When you use a battery with a low discharge rate,and open it to 50W, the battery will not provide so much current, so the voltage will drop sharply, but after you release it, the battery stops outputting voltage and automatically picks up.

Then how do we choose the pressure regulating device battery? The first thing you need to know is how much power you normally use, so that we can determine the constant discharge current , and then use this data to select the battery's capacity so that you can maximize battery performance.


For instance: If  the device is a single electricity mod with 70W,and the screen display voltage is 3.7V, then according to the formula power / voltage = current, we can come to 70/3.7 = 18.91A this value, Then you only need to use a battery with a maximum continuous discharge of 20A.

For "dual-powered" mainframes, it is divided into the  "series" and the "parallel" two forms: the series voltage is equal to the sum of all battery voltages, the current is equal to the current flowing through each battery, and the parallel voltage is equal to a single battery voltage, current is equal to the sum of battery currents.

If you use a dual-powered series mainframe, then the calculation is slightly more troublesome.

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Since the internal resistance of the battery is increased after the dual series connection, the maximum continuous discharge current will be lower than that of the original single cell. Let's be conservative and make a 70% discount, then the original 20A battery will become 14A.

Then we take a look at how to calculate the dual-powered series mainframe, still 70W, the screen display voltage is 3.7V, because it is connected in series, the actual operating voltage of the battery may be 7.4V, then the actual battery output current is 9.459A, you will see, a single 20A battery can still support this current well.

The operating current is 140/4.2=33.333333, the battery input voltage may still be 7.4V, the actual output current is 18.9A, you can see the demand current is greater than provide current, but it involves the problem of adjusting high voltage to low voltage to increase the current, so we can roughly calculate it, because of the voltage regulating equipment,its output voltage is actually relatively fixed, so we can roughly calculate the required current, such as the highest power 200W , the maximum output voltage of the chip is 7.5V, then 200/7.5=26.66A, using a 30A battery(the actualcuttent is 21A) can barely achieve the effect of use.

If the discharge is lower than the calculated value, it will show low voltage even through the power still has one third of the time, and the set output power cannot be achieved.


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