How to Select a USB Battery Charger
USB is a ubiquitous interface for powering and charging devices. It can be used as a standalone device or integrated into your mobile phone.
USB is a complex technology that can be difficult to understand. It is a good idea to know some basics before purchasing a USB battery charger.
Charger Type
An USB battery charger, or power bank, charges a battery connected to a port on a portable device. It is often used to charge a tablet, smartphone or camera with a compatible USB cable. A good quality usb battery charger can be expected to charge the battery quickly and efficiently.
The type of usb battery charger that is most suitable for you depends on the types of devices that you typically use, and the power demands of those devices. For example, a smaller tablet may only need a 5V USB connection to be charged from a USB charger, whereas a larger smartphone will require more current and voltage to be charged.
There are several types of chargers that are available, including timer based, buck-boost and universal. Timer based chargers are commonly used for consumer Ni-Cd batteries and charge them according to the capacity of the batteries, not their state of discharge.
Buck-boost chargers are usually less complex than timer chargers and are able to charge all cell chemistries. They charge a battery in a predetermined time interval, with the output terminated once the battery has reached its full capacity or when it is disconnected from the charger.
A buck-boost charger is also capable of delivering power to external devices that are not connected to it. This makes it a convenient way to charge your phone or other portable device when you are out of reach of a wall outlet.
Most modern USB ports, including the newer, faster ones like the USB-C connection, have multiple levels of charging capabilities. In addition, they can support power delivery standards such as PD, which allows for a more flexible approach to fast charging.
As with any power management system, it is important that the power source be regulated and limited to an appropriate level. This prevents over-charging of the battery or causing damage to the circuits. It should also be able to deliver a clean, regulated voltage output with tight limits on spikes, ripple and noise to avoid harming the battery or the circuits that are being powered.
Charger Amps
Charger amps are a key factor when it comes to the charging speed of your device. Generally, you want to look for chargers with higher amps. This is because it will allow you to charge your mobile device faster than a charger with a lower amperage.
Keep in mind, however, that you shouldn’t go overboard on your amperage. You may find that your charger is not able to deliver the power your device needs, and this can lead to overheating and other problems.
This can also shorten the lifespan of your device, so it’s best to stick with the recommended amperage for your specific model. If you’re not sure what to choose, consult your phone’s usb battery charger owner’s manual or contact the manufacturer to learn more about their recommendations.
In most cases, you can expect your battery pack to be rated at 1 to 2.4 amps. This number refers to how much power it can take in, which varies depending on your battery’s capacity and the battery pack’s input current. A high-power battery pack, on the other hand, has a higher input current, so it will recharge faster.
A standard USB plug typically has four pins, with the two shorter ones carrying data and the longer one delivering a +5 volt supply. When a charger is connected to this port, it will negotiate the required current with the battery pack for the fastest possible charge.
You can even get some chargers that offer features like reverse polarity protection, which will help you avoid recharging your battery pack in the wrong direction. Some even detect a faulty battery and stop charging until it’s replaced.
Another interesting feature is voltage regulating, which can make a charger run up to 20% faster. This can be handy when you need to charge your battery pack quickly, or if you have multiple devices that need to be charged at the same time.
If you’re looking for a charger that can do a lot, the Boost Plus from NOCO is a great choice. This charger can recharge your battery from a completely dead state and it’s compatible with diesel engines up to 3.0 liters. It also offers a lot of other useful features, including battery detection and thermal limiting to reduce charge current to maintain a low die temperature during ambient extremes.
Charger Ports
The USB port is a data port on computers and laptops but also serves as a 5-volt power source for personal handheld electronics like cell phones, PDAs, and digital music players. Using the USB charger on one of these devices will recharge your battery quickly, and may help prolong its life.
The original USB ports (versions 1.0 and 2.0) can charge a single-cell Li-ion battery at up to 5V 500mA. However, when multiple devices are attached to a port, charging can cause a voltage drop and potentially cause the system to fail. To avoid this problem, some USB host designs include current-limiting circuits to shut off the port’s power when too much load is plugged in at once.
Another solution to this problem is to use a dedicated charging port that can supply up to 1.5A and does not enumerate to the system, thus allowing charging to occur without any digital communication at all. This type of port is called a DCP and is commonly found on USB wall warts, which feature a micro or mini USB receptacle and can be inserted in any USB cable with the correct plugs.
BC1.1 expands the USB spec to allow “dumb” methods for determining port type, so that, in some cases, charging can occur without enumeration and the initial digital communication between the device and host. This should reduce the costs of charging and lead to better interoperability as standard adapters emerge.
When the USB charger is connected to the battery, it uses its own IC to determine the port type and negotiate the current limit. The IC selects the right USB load current limit for its application and communicates with the host through its own interface.
The device also connects 1.5kO pull-up resistors to the D+ and D- data lines that carry battery impedance and power limits (Figure 2). If the impedance is too high or the power limits are too low, the charger suspends the charging process until the battery impedance reaches its normal value or the power limits are reestablished.
The USB Charger IC is a powerful tool that speeds design and saves time and money by avoiding the need usb battery charger for complex power management hardware in the device and by providing a safe, efficient charging experience. Choosing the right USB Charger IC and designing it to deliver exactly the right amount of power at the optimal speed is key to delivering a superior user experience, optimizing battery lifespan, and lowering customer returns and warranty repairs.
Overall
Battery charging is a complex and multifaceted task. Properly identifying and selecting the best charger can optimize safety, performance, and cost for portable devices that rely on Li+ batteries. The overall design of a USB battery charger requires careful considerations that balance a number of factors including power limitations, size and weight, and user comfort.
In order to achieve the most efficient charge, the charger IC must be able to detect and select an appropriate USB load current limit based on input voltage, charging requirements, and system architecture. It also must provide a way to switch the charge circuit on and off in the event of an external event. Thankfully, National Semiconductor has designed a line of USB charger ICs that are well suited to this task.
The most important function of a USB battery charger is to deliver a good charge to the Li+ battery that powers the device. This is typically accomplished through a series of step-ups that increase the battery’s output to the required voltage. This is accomplished by a buck-boost circuit with an integrated battery FET that boosts the output by a factor of two or more over the nominal voltage.
Aside from the obvious NVDC technology, this charger has a few other tricks up its sleeve that can make it an excellent choice for your next power hungry portable. For example, a smart charging circuit that senses when an alkaline cell is inserted will suspend charging in the event of a mishap, saving you from wasting time and money on a repair.
