All battery chargers have one thing in common: they work by feeding a DC electric current through batteries for a period of time in the hope that the cells inside will hold on to some of the energy passing through them. That's roughly where the similarity between chargers begins and ends!
There are, broadly speaking, two different ways to charge a battery: quickly or slowly. Fast charging essentially means using a higher charging current for a shorter time, whereas slow charging uses a lower current for longer. That doesn't mean the charging process is just a simple matter of passing a steady current through the battery until it's charged. There are several common methods of charging (plus a few more we won't go into here). [1]
Photo: Battery chargers look simple, but they're surprisingly complex inside. Different types of rechargeable batteries need charging in different ways, for different times, sometimes using several different methods in turn, which make up what's called the charging algorithm. A charger like this is constantly sensing what the batteries inside it are doing and adjusting the charging process accordingly.
Pulse charging involves sending intermittent pulses of high current through the battery, with rest periods in between to allow the battery chemicals to absorb the charge. In crude terms, the pulses are a little bit like the thumping charges to the chest you see an emergency responder giving to someone who's suffered a cardiac arrest, except that they continue until the battery's voltage climbs toward its rated, peak value and the battery is fully charged. (Pulse charging can also be useful for reviving older, degraded batteries, such as lead-acid or nickel-cadmium, in which crystals have grown and impeded the batteries' ability to keep on working; the pulses of electricity break the crystals down so the battery works normally again.)
In taper-current charging, the charger starts off using a high, constant current, which progressively lowers to a trickle as the battery fills with charge and reaches its peak voltage. Inexpensive chargers often work this way. [8]
Two alternative ways of charging are constant current (CC) and constant voltage (CV). As their names suggest, constant current applies a steady current (usually the battery's peak current), while constant voltage applies a steady voltage (usually the battery's peak voltage), and the two are often used together, one after another, in constant current constant voltage (CCCV) chargers. Typically, they start off applying a constant current until the battery voltage passes a certain threshold; then they apply a constant voltage until the current passes another threshold. Another variation is two-step constant-current charging that begins with a fast high-current charge and switches to a slower, lower-current charge part way through the process. [9]
Photo: This "fast-charge" battery charger is designed to charge four cylindrical nickel-cadmium (nicad) batteries in five hours or one square-shaped RX22 battery in 16 hours. I think it's an example of a constant-current or maybe taper-current charger, though I've not tested it to find out. It's easy to use, and just as easy to misuse: there's nothing to tell you when charging is complete. With a battery charger like this, charging batteries is complete guesswork.
The final method is called trickle charging, and is similar to constant current charging but uses a much smaller current (perhaps 5–10 percent) for much longer. Some appliances (like cordless phones and electric toothbrushes) are designed to sit on trickle chargers indefinitely.
However you charge, it's worth remembering that, in a very crude sense, batteries are a bit like suitcases: the more you pack in, the harder it is to pack in any more—and the longer it takes. That's easy to understand if you remember that charging a battery essentially involves reversing the chemical reactions that take place when it discharges and supplies useful current. In a laptop battery, for example, charging and discharging involve shunting lithium ions (atoms missing electrons) back and forth, from one electrode (where there are many of them) to another electrode (where there are few). Since the ions all carry a positive charge, it's easier to move them to the "empty" electrode at the start. As they start to build up there, it gets harder to pack more of them in, making the later stages of charging harder work than the earlier ones.
Graph: Batteries get harder to charge in the later stages. It can take as long to charge the last 25 percent of a battery (red area) as the first 75 percent (orange area). [2] It's worth remembering this if you have limited time to charge a battery and worry that it'll take too long: you might be able to charge it halfway in much less time than you think. If the battery in this example takes an hour to charge, you can see that it would reach 50 percent charge (dotted lines) in just 6.5 minutes.
Different charging methods are suited to different types of batteries. Simple pulse charging works well for nickel cadmium and nickel metal-hydride batteries, which are also widely charged by the constant current (CC) method, but pulse charging is quite crude and unsuitable for lithium-ion batteries, which are generally charged by CCCV instead.
Better chargers work more intelligently, combining different types of charging in sequence according to how the battery performs as it's being charged. So, for example, a battery may be slowly pre-charged (by trickle charging) for a short time to test how well it's accepting charge, then fast-charged fully by CC and CV, which may be alternated multiple times. [3] The combination of charging methods used by a particular charger is known as its charging algorithm.
Graph: A simple charging algorithm might involve three stages: brief trickle charging to test the battery followed by periods of fast constant-current and constant-voltage charging. [7]
The ideal charging time varies for all sorts of reasons (how much charge the battery held to begin with, how hot it is, how old it is, whether one cell is performing better than others, and so on). How does a charger know when to stop? Different methods are used for different types of batteries, and for slow charge or fast charge. The best chargers work intelligently, using microchip-based electronic circuits to sense how much charge is stored in the batteries, figuring out from such things as changes in the battery voltage (technically called delta V or ΔV) and cell temperature (delta T or ΔT) when the charging is likely to be "done," and then switching off the current or changing to a low trickle charge at the appropriate time.
There's usually a primary method of figuring out that the charge is complete (such as measuring the voltage) and one or more backup methods (temperature changes or a preset timer). [4] NiCd chargers, for example, often use a primary method called −ΔV (also written negative delta V or NDV, which refers to the slight voltage drop that a NiCd battery shows just after it's fully charged), with a backup timer or temperature-change detector. NiMH chargers are more likely to rely on temperature changes as their primary method with a backup timer cut-off circuit. In theory, it's impossible to overcharge or undercharge with an intelligent charger.
Photo: The Innovations Battery Manager, popular in the 1990s, was sold as an intelligent battery charger capable of recharging even ordinary zinc-carbon and alkaline batteries. Right: A digital display showed the voltage of each battery as it charged (in this case, 1.39 volts). After charging, a little bar graph appeared showing how good a condition the battery was in (how many more times you could charge it). Many thousands of these chargers were sold, but there were differing opinions on how well they worked.
If you're charging batteries, you probably think fast charge is automatically better—you want to use your laptop or phone as soon as you can. But it comes with major drawbacks. The chemicals in batteries take time to absorb charge and faster charging can shorten the life of a battery (a big problem for things like expensive electric car batteries), or risk safety problems such as overheating and fires. [5]
Most chargers are designed to charge two, three, or four batteries at the same time, which adds a few extra complications. If you simply connect them in series and try to charge them, how do you know which batteries are in a good condition and charging well and which ones are poorer and accepting less charge? One battery is almost certain to reach full charge before the others, so it's almost inevitable that some will be overcharged (and potentially damaged) while others remain undercharged. Decent battery chargers get around this with circuits that monitor each battery individually, switching off or reducing its charging current to a trickle, independently, when it's fully charged. [6]
Batteries are direct current (DC) devices: current flows in one way (during charging) and out the other (during discharging). But most of us live in homes with alternating current (AC) supplies, so plug-in battery chargers have to convert AC electricity to DC before they can charge the batteries you want to put into them. Exactly how they do this affects the quality of the DC charging current and how cleanly and effectively they charge. Typically, AC-powered chargers use some combination of step-down transformers (to convert high voltages, typically 110–240 volts, to lower ones more like 1.5–20 volts); rectifiers (diode-type circuits) and thyristors (silicon controlled rectifiers), to convert AC to DC; and integrated circuits to filter and smooth their output.
To complicate matters, different types of rechargeable batteries respond best to different types of charging, so a charger suitable for one type of battery may not work well with another.
Photos: An electric toothbrush typically contains either nicad or NiMH batteries and slowly or trickle charges on a stand, which is actually an induction charger.
Nickel cadmium (also called "nicad" or NiCd), the oldest and perhaps still best known types of everyday rechargeable batteries, respond best either to fairly rapid charging (providing it doesn't make them hot) or slow trickle charging. [10]
Nickel metal hydride (NiMH) batteries use newer technology and look exactly the same as nicads, but they're generally more expensive because they can store more charge (shown on the battery packaging as a higher rating in mAH or milliampere-hours). NiMH batteries can be fast charged (on high current for several hours, at the risk of overheating), slow charged (for about 12–16 hours using a lower current), or briefly trickle charged (with a much lower current than nicad), but they should really be charged only with an NiMH charger: a rapid nicad charger may overcharge NiMH batteries.
Expert opinions seem to differ on whether nickel batteries experience what's widely known as the memory effect. This is the well-reported phenomenon where failure to discharge a nickel-based battery before charging (when you're "topping up" a partly discharged battery with a quick recharge) reputedly causes permanent chemical changes that reduce how much charge the battery will accept in future. Some people swear the memory effort is real; others are equally insistent that it's a myth. The real explanation for an apparent memory effect is voltage depression, where a battery that hasn't been fully discharged before charging temporarily "thinks" it has a lower voltage and charge-storing capacity than it should have. Battery experts insist you can cure this problem by charging and discharging a battery fully a few times more.
It's generally agreed that nickel-based batteries need to be "primed" (charged fully before they're used for the first time), so be sure to follow exactly what the manufacturers say when you take your new batteries out of the packet.
There are two simple reasons why there are so many different sizes and types of batteries: a bigger battery has more chemicals inside it so it can store more energy and release it for longer; bigger batteries also tend to have more cells inside them so they can produce a higher voltage and current to power bigger things (brighter flashlight bulbs or higher-powered motors). By the same token, bigger rechargeable batteries need charging for longer. The more energy you expect to get out of a rechargeable battery (the longer you expect it to last), the longer you'll need to charge it (or the higher the charging current you'll need to use). A basic law of physics called the conservation of energy tells us you can't get more energy out of a battery than you put into it.
Most people tend to put things on to charge "overnight" without paying too much attention to exactly what that means—but your batteries will work better and last longer if you charge them for the right number of hours. How long is that? It can be very confusing, especially if you use batteries that didn't come supplied with your charger. Never fear! All you have to do is read what it says on your batteries and you should find (often in tiny writing) the recommended charging current and charge times. If you have a basic charger, simply check its current rating and adjust the charge time accordingly. Bear in mind what we've said elsewhere about matching your charger to your batteries, however.
Photo: Battery science is not rocket science—charging rechargeables is easy if you follow the instructions, generally written on the batteries or the package they came in.
For example, these three ordinary, 1.2-volt nickel-based rechargeables have quite different recommendations:
Lithium-ion rechargeable batteries are usually built into gadgets such as cellphones, MP3 players, digital cameras, and laptops. Typically they come with their own chargers, which automatically sense when charging is complete and cut off the power supply at the right time. Lithium-ion batteries can become dangerously unstable when the battery voltage is either too high or too low, so they're designed never to operate under those conditions. If the voltage gets too low (if the battery discharges too much during use), the appliance should cut out automatically; if the voltage gets too high (during charging), the charger will cut out instead. Although lithium-ion batteries don't show a memory effect, they do degrade as they get older. A typical symptom of aging is gradual discharge for a period of time (maybe an hour or so) followed by a sudden, dramatic, and completely unexpected cut-out of the appliance after that. Read more about how lithium ion batteries work.
Photo: An idiot-proof Canon charger for lithium-ion camera batteries. When the battery needs charging, the camera warns you well in advance. Simply remove the battery (very easy on a digital camera), put it the separate charger unit, and the indicator light shows red, turning green when the battery is fully charged. The whole process is automatic and safe: the camera stops you using the battery before its voltage gets too low; the charger stops you charging it before the voltage gets too high.
The biggest, heaviest, and oldest rechargeable batteries take their name from their (dilute) sulfuric-acid electrolyte and lead-based electrodes. They're most familiar to us as car batteries (the initial energy supplies that get a car engine turning over before the gas starts burning), though slightly different types of lead-acid batteries are also used in things like golf buggies and electric wheelchairs.
Photo: Lead-acid car batteries were originally developed in the 19th century, long before nickel- and lithium-based rechargeable technologies came along.
Lead-acid batteries are popular because they're simple, cheap, reliable, and use well-proven technology that dates back to the middle of the 19th century. Generally they last for several years, though that depends entirely on how well they are maintained—in other words, charged and discharged. They do take quite a long time to charge (typically up to 16 hours—several times longer than they take to fully discharge), and that can lead to a tendency both to undercharge (if you don't have time to charge them properly before you next use them) or overcharge (if you put them on charge and forget all about them). Undercharging, charging with the wrong voltage, or leaving batteries unused causes a problem known as sulfation (the formation of hard lead sulfate crystals), while overcharging causes corrosion (permanent degradation of the positive lead plate through oxidation, analogous to rusting in iron and steel). Both will affect the performance and life of a lead-acid battery. Overcharging also tends to degrade the electrolyte, decomposing water (by electrolysis) into hydrogen and oxygen, which are given off as gases and therefore lost to the battery. That makes the acid stronger and more likely to attack the plates, which will reduce the battery's performance. It also means there's less electrolyte available to interact with the plates, also reducing the performance. From time to time, batteries like this have to be topped up with distilled water (not ordinary water) to keep the acid at the optimum strength and at a high enough level to cover the plates.
Different battery chargers are designed to work in different ways at different speeds, largely to suit different types of batteries. The first rule of battery charging is that a charger designed for one kind of battery may not be suitable for charging another: you can't charge a cellphone with a car battery charger, but neither should you charge NiMH batteries with a nicad charger. Many modern rechargeable appliances and gadgets—such things as laptops, MP3 players, and cellphones—come with their own, special charger when you buy them, so you don't have to worry about matching the charger to the battery. But if you buy a packet of generic, rechargeable batteries in a store, it's important that you buy batteries that suit the charger you have or replace your charger accordingly. Note the voltage and current that the batteries require (it will be marked on the battery package or on the batteries themselves), be sure to choose a charger with the right voltage and current to go with them, and charge for the correct amount of time. If you want to buy yourself some rechargeable batteries but you're not really sure how to go about matching batteries and charger, go for a combined set—where you buy batteries and charger in the same package.
Photo: Matching the battery to the charger. As the world shifts to more environmentally friendly battery-powered electric cars, we'll need a lot more properly equipped, conveniently sited charging stations. This one uses photovoltaic solar cells (in the canopy) to charge the vehicles parked below. Photo by Dennis Schroeder courtesy of NREL.
Not surprisingly, it depends on how you treat them, store them, and use them. Small rechargeables (like NiCd, NiMH, and lithium ion) typically last hundreds of "cycles" (you can charge and discharge them that many times), which can mean anything from several years of decent life in a laptop to a decade of use in a portable radio. Treated well, lead-acid car batteries are usually good for thousands of cycles and can easily last 5–10 years in a car that's driven each day. But if you leave rechargeable batteries in a product you barely ever use, never charge or discharge them, overcharge them, let them overheat, or store them in poor conditions, don't expect them to last long.
How do you know when it's time to replace batteries? In something like a laptop, you might notice a lithium-ion battery discharges normally for a time, then suddenly loses all its remaining charge very quickly. If you're using rechargeable NiCd or NIMH batteries in things like flashlights, you'll see very gradually reducing capacity and the need to recharge much more often.
How can you get the best from your batteries? Here are some top tips I've found by reading through a variety of battery-expert websites:
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In today's fast-paced world, we all rely on our phones to get through the day. Charging your phone or tablet is now a necessity; however, it can also be a pain. This is especially true if you're not sure what kind of charger you should use for your device. If you're not tech-savvy, don't worry! We've got all the info you need to know about different types of USB chargers and how to know and pick the best one for your needs.
USB stands for Universal Serial Bus. It has been around since 1996 and was originally designed for connecting peripherals like keyboards and pointing devices to personal computers. Since then, it has developed to encompass a wide variety of devices and become the standard for charging.
In today's generation, we commonly use USB as a connector for our smartphones and tablets. Once connected, the USB be used to charge your phone, transfer data between devices (like your computer), or both at once!
Explore more phone chargers if you need it: Anker phone charger collections>>
Pretty excited to know what are the different types of chargers? Let's look in-depth at the top 6 phone charger types available in the market today!
A USB-A charger is one of the old phone charger types. It's most generally used with computers or power outlets. You can attach the USB-A side to the USB plug of a laptop when charging. Remember that USB-A wires will just go one way into the port. You can normally know which way up they must be by the USB symbol that can be seen on the top.
USB-A types of chargers can only accommodate USB-A ports, which are now starting to be phased out in modern host devices.
USB-B ports are less common than the various other phone charger cable types. It's a four-pin USB port that can be found on many devices, including printers, scanners, external hard disks and more. The port has two rows of pins that are used to connect the device to your computer. The USB-B port can also be used for charging devices like smartphones or tablets, but it cannot send data back and forth from your device to a computer.
The mini-USB connector was once commonly found on phones, cameras, and similar small devices for connecting those devices to computers and other devices. The mini-USB connector has since been phased out in favor of different phone chargers, the micro-USB connector.
The Micro-USB port is one of the most popular types of charging cords. It's found on many mobile devices, as well as many other electronic devices like cameras and keyboards. This type of USB allows data to be read without needing a computer (i.e., flash drives & memory sticks). However, like USB-A cables, these types of phone charger ends only go into a port if it matches its shape, so be careful so you won't damage anything.
USB-C cables are the latest technology for charging your laptop, tablet, or phone. It's different from the old micro-USB and mini-USB adapters because it's a reversible connector—that means you don't have to worry anymore about which side goes in first!
USB-C charging adapters are also a more efficient Android charger type (among others), so they can charge your device faster than ever. The fun part? It's not only limited to Android because it's available in USB-C to Lightning cable for your iOS devices!
The Lightning charger (one of the cell phone charger types) is an Apple-designed connector that replaces the old 30-pin dock connector used on the original iPhone 4 and iPhone 3. The Lightning charger now has 8 pin lightning connector on one end and a USB Type-C connector on the other end. These chargers are designed to work with all of the major Apple products, including iPhones, iPads, and iPods, to host external monitors, computers, USB battery chargers, cameras, and other peripherals. USB-A to Lightning cable is also available on the market, so your devices with USB-A ports won't be left behind.
So, there you have it! A detailed look at the various types of chargers for phones available on the market. Remember that when it comes to charging your phone, there's a lot more than just plugging it in. There are different phone chargers and cables you can use to make sure your device gets the most out of its battery life. We hope that this compilation guide helped you find the best one for your needs!
Here are the top commonly asked questions about the different phone charger types.
USB-A and USB-C are two types of cables that allow you to transfer data between your computer and external devices. USB-A is the most common USB cable type, and it's what you'll find on the end of your computer's charger or in a flash drive case. It's rectangular, with a flat top and bottom.
USB-C is newer than USB-A and has a different shape: it's rounded at both ends, with one side wider than the other. Moreover, unlike USB-A, it has a reversible connector, which means you can plug in the connector either way. It also supports faster data transfer speeds, which means that if you have a device that supports USB 3.1 or even Thunderbolt 3 (which runs on top of USB), then you'll want to use a USB-C cable to connect it.
The main difference between Lightning and USB-C is that Lightning is Apple's proprietary connection to charge your iPhone. In contrast, USB-C is a standard connection that many different kinds of devices can use. Not to mention that USB-C is what does an Android charger look like for most now.
No. USB-C is a newer standard that offers higher power delivery rates and faster charging under the same voltage. USB-C carries 3A with up to 5A support, while Lightning just supports a maximum current of 2.4A. This means that USB-C supports the USB Power Delivery fast-charging standard, making it much better for fast charging than Lightning.
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