How to build a simple laptop power bank circuit that can be used for charging a laptop battery during traveling or during outdoor trips.

 

The following article describes how to create an easy laptops power bank circuit that may be used to recharge a laptop battery while travelling or on an outdoor adventure. This tool may be especially beneficial on conditions or locations wherein an AC mains outlet is unavailable or tough to find.

 

 

Why Laptops Need a Battery 

 

Just like smart phones, laptops are also transportable devices that require a battery to function while there's no mains AC supply available. This is the primary benefit of laptops over PCs when you consider that a PC may be carried with us whilst touring and may be operated from anywhere outdoors. This will become viable due to the fact that a PC has an in-built battery. The battery provides the specified electricity supply to the tool on every occasion required, allowing the PC to operate without the need for an AC mains supply outlet. Laptops are so portable and handy that they can be opened and operated by anyone sitting on the pinnacle of their laps, hence the term "PC. 

 

 

Which battery is utilised in laptops?

 

In most instances, the preferred battery for a computer is a Li-Ion battery. Li-ion batteries are one of the most environmentally friendly styles of batteries with a totally excessive electricity-to-weight ratio. Power-to-weight ratios mean that the battery is able to present lengthy backups without excessive electricity fees through incredibly small, light-weight packages.The voltage specs of a computer may also vary for extraordinary laptops. Some computers may use a 11.1 V battery, some laptops may use a 14.4 V battery, and some computers may use batteries with higher voltage ratings. 

 

A computer battery's typical current score is around 4000 mAh, which can provide backup energy for approximately four hours. In this article, we are able to discover ways to construct a computer energy financial institution circuit for a computer with the use of a 11.1 V Li-Ion battery. The 11.1 V computer battery makes use of six Li-Ion cells, each rated at three.7 V. The six cells are configured as 3S2P, meaning that parallel units of batteries each have three cells in series. The mAh score of every smart phone will be around 2000 mAh. Therefore  parallel units might bring about a complete mAH score of 4000 mAh.

 

Since there are 3nos of 3.7 V Li-ion cells involved, the whole voltage of the computer battery becomes: 

  

 V = 3.7 + 3.7 + 3.7 = 11.1 V 

  

 This 11.1 V fee is the extent to which the battery is at an absolutely discharged state. 

  

 Since the entire price fee of every 3.7 V Li-Ion smart phone is 4.2V, the whole fee of a completely charged 11.1 V computer battery might be: 

  

 V = 4.2 + 4.2 + 4.2 = 12.6 V

 

 

 

  How to Build a Laptop Power Bank Circuit 

  

The concept of the computer energy bank circuit is simple. We need to apply a hard and fast chargeable battery inside the energy bank, which has a better voltage specification than the computer battery. 

  

This means, whilst the better voltage from the energy energy bank, is hooked up to the computer battery, the fee from the energy bank battery begins to shift into the computer battery. This is maintained till the computer battery is completely charged and the energy bank battery is discharged. 

  

Since the computer battery has two parallel units of batteries with three collection cells on every set, we can use a better configuration of 4S2P. That is, our energy bank can have two parallel units of batteries, each with four cells in its collection. With a configuration of four collection cells, the overall completely charged voltage of our energy bank circuit will be: 

  

 V = 4.2 + 4.2 + 4.2 + 4.2 = 16.eight V. 

  

 To allow the configuration to have a specification of 16.8 V, 4000 mAh, 

 

The complete connection diagram of the laptop power bank battery can be seen in the following figure

 

 

 In the above figure, we are able to see how a 4S2P (four series, two parallel) aggregate of Li-Ion cells is configured to construct a strong battery voltage of 16.8V.    The specs of every one of the cells used inside the battery pack are as follows:    Li-Ion Cell = Type 18650    Voltage = 3.7 V    Capacity = 2000 mAh.

 

 

Using a Voltage Regulator 

 

Although now we've a smooth pc strength bank installation and geared up with us, the 16.8 V output isn't always secure to be implemented at once to a pc battery. Therefore, we want a voltage regulator that might adjust the 16.8 V right into a regular 12.6 V. 

For this, we once again depend upon our workhorse regulator, IC LM338. 

 

Using IC LM338 and some different passive components, we are able to construct a totally efficient, full-fledged PC strength bank charger circuit, as proven in the following figure.

 

 

In the above design, the potentiometer R2 has to be exactly adjusted to get 12.5 V on the output, which may be then used for charging a laptop battery. Although the whole price stage of an 11.1 V laptop battery is 12.6 V, we should regulate the output from the LM338 to exactly 12.5 V, which is 0.1 V less than the whole price value. This guarantees that the laptop battery can in no way get overcharged, although the energy bank circuit is hooked up indefinitely with the laptop battery.

 

 

Calculating the Constant Current Resistor 

  

Another thing that Li-Ion batteries are usually essential for is the charging edge, which needs to be regular and limited. That's precisely why RX is located inside the above-proven LM338 circuit. 

  

You will need to modify the cost in order that it limits the cutting-edge to a regular 0.five C cost. That's equal to 50% of the computer battery's mAh rating. 

The cost of the RX may be constant with the use of the subsequent formula: 

  

 RX = 0.6/2 amps = 0.three ohms. 

  

 Wattage = 0.6 x 2 = 1.2 watts, or 2 watts. 

  

 Make certain to use an amazing heatsink on the IC LM338. 

  

 0.6 V indicates the flip-on voltage of the BC547 transistor. When the modern intake attempts to exceed the two amp cost, a voltage of 0.6 V spreads throughout the 0.three ohm resistor, causing the BC547 to turn on. When the BC547 switches on, it shorts the ADJ pin of the LM338 to ground, shutting it off. Shutting off LM338 at 2 amp continuously prevents the charging cutting-edge from exceeding the two amp mark.

 

 

How to Charge the Power Bank? 

 

That's a legitimate question. 

 

Before you can take the energy bank unit with you for charging the PC battery, you need to make certain the energy bank battery is itself absolutely charged. In any other case, it may not serve the purpose. 

The idea is simple: assemble every other LM338 voltage regulator that is identical to the one shown in the above image. However, for the reason that the energy bank battery pack's complete rate voltage degree is 16.eight V, the output voltage from the LM338 regulator should be adjusted to a particular 16.7 V. 

The entire circuit diagram for the energy bank charger may be seen in the following figure.

 

Again, right here too, we regulate the charging voltage at 0.1 V, much less than the overall fee stage of the battery to ensure the battery is in no way completely charged. 

This concludes our article on the way to construct a computer electricity financial institution circuit. If you have any additional questions, please let me know through the below comment box. I will attempt to resolve your queries ASAP.