Teardown - USB Batteries

2017-01-25 | By All About Circuits

License: See Original Project

Courtesy of All About Circuits

USB battery packs are very popular and are sold nearly everywhere. What’s inside of them? Find out in this teardown, as we take a look at the insides of four different batteries! This teardown features an Anker Astro E3 10,000mAh, an Anker Astro E1 5,200mAh, a Generic ‘Lipstick’ Style 2,200mAh, and an Aibocn 10,000mAh Power Bank 2 batteries. Many of these USB batteries are manufactured relatively inexpensively and use generic components. Due to that fact, this teardown won't be as in-depth as some of the others, but it will still give you an idea of the functionality and construction of these devices. Most of the IC’s found in this teardown do not contain any part number or manufacturer markings on them.

Block Diagram Overview

A Typical Design for a USB Battery Pack

The designs of these four battery packs are all pretty similar. They all contain a battery, battery protection, charging circuits, and a step-up voltage regulator. The block diagram above shows the typical design for these batteries.

Battery Cells

In order to store the power, these portable USB chargers contain battery cells. These USB chargers typically contain various types of Lithium batteries. The battery cells in these will be in two formats: cylindrical cells or prismatic cells.                                                         

Astro E3

The 2 Cell Battery in the Anker Astro E3 USB Battery

The Astro E3 battery has an advertised capacity of 10,000mAh. Inside the clipped together plastic body there are two prismatic lithium cells that have polarity indicators, “5666113PRJ”, and “DKT 20130428A” printed on them. The first number printed onto the cells refers to their size. These cells are 5.6mm thick, 66mm wide, and 113mm long. Each of these cells is rated at 5,000mAh and are wired in parallel to get 10,000mAh.

Astro E1

The 2 Cell Battery in the Anker Astro E1 USB Battery

The Astro E1 battery has an advertised capacity of 5200mAh. Inside of its tightly sealed outer shell, there are two 18650 sized cylindrical cells that have polarity indicators, “CMICR18650F8”, and “3.7v 2600mAh 8C” printed on them. Ankers’s product page lists the cells as “premium”, a search of the part number shows that these are most likely manufactured by Samsung.

Lipstick Style Battery

The PCB and Battery Cell in the Lipstick Style USB battery

This generic Lipstick USB battery has an advertised capacity of 2200mAh. Inside of the generic Lipstick style USB battery is a single cylindrical 18650 size Lithium-Cell. Printed on the cell are the polarity indicators, “18650 7E42114 80938”, a barcode, and “CJ”. Decoding the numbers, 18650 is the size, 7E42114 appears to the be the batch number, and 80938 appears to be the part number.

Aibocn

The 2 Cell Battery in the Aibocn USB Battery

This Aibocn USB battery has an advertised capacity of 10,000mAh. Inside of the Aibocn USB battery are two prismatic cells that are wired in parallel. The taped together cells have polarity indicators, “HL RJ5 3.7V”, and “SP5666113 BL3” printed on them. These cells are the same physical size as the ones used in the Astro E3 battery.

PCB’s

There’s a lot going on inside these USB batteries. From time lights, switching power supplies, and charging circuits; the circuit boards are packed full of components.  

Astro E3

The PCB in the Anker Astro E3 Charger

Most of the components are inside the Astro E3 residue of the top side of the PCB. Located on the bottom of the PCB is the switching regulator that is thoroughly covered by a potting/thermal compound.

Astro E1

The PCB in the Anker Astro E1 Charger

The Astro E1 has components throughout both sides of its circuit board. There is no thermal management on this small PCB. On the top of the PCB, there are the USB connectors, a power supply, battery protection IC’s, and a large capacitor. On the bottom of the PCB, there is an IC to control the charge indicator lights, switching fets, and a large piece of foam to separate the four blue LED lights.

Lipstick Style Battery

The Lipstick Style Battery’s PCB

Out of all these batteries, this one has the smallest PCB! Nearly all of the components are on the top of the PCB. On the bottom of the PCB are the IC’s that provide overcurrent and under voltage protection, as well as the USB socket.

Aibocn

The Abiocn’s PCB

The Abiocn battery has most of its components on one side of its PCB. A small block of thermal material was adhered to the switching regulator (top right). On the back of the PCB, there is the IC to control to the charge level indicating lights.  

Voltage Regulators

A key component of these battery packs is the voltage regulators. The batteries inside of these devices have a nominal voltage of 3.7v. USB devices typically recharge off of 5v (or sometimes greater in the case of Qualcomm Quick Charging). Due to this voltage difference, step-up or boost regulators are used. These regulators will often have a boost controller, a diode, an inductor, a switching MOSFET, and an output capacitor.

Astro E3

The Heatsink for the Voltage Regulator on the Astro E3 Charger

The voltage regulator in the Astro E3 is buried underneath a glob of potting/thermal compound with an aluminum heatsink firmly attached to it. Despite this, the blocking diode and inductor are visible.  

Astro E1

The Inductor and Voltage Regulator IC on the Astro E1

The Astro E1 charger has its power supply more accessible to peering eyes. The inductor, blocking diode, and boost controller are visible on the top side of the PCB. The switching fets are on the bottom of the PCB.  

Lipstick Style Battery

The Voltage Regulator of the Lipstick Style Battery, top right.

The Lipstick style battery uses a boost regulator as opposed to a boost controller. One of the big differences between a boost regulator and a boost control controller is the switching FET inside of the regulator. In the image, the inductor, regulator, and blocking diode are visible in the top right corner of the pcb.  

Aibocn

The voltage regulator on the Aibocn battery

Similarly to the Lipstick USB battery, the Aibocn USB battery pack uses a voltage regulator. When the battery pack is fully assembled, the voltage regulator has a thermal material on the top of it. Located to the left of the voltage regulator is an inductor with a QC label on the top of it.