Charging Your iPad – It’s All About Watts

One of the standout features of the iPad is its long battery life—a fully charged battery should last about 9-10 hours for everyday tasks like accessing the Internet, and 4-5 hours when used in an airplane for navigation. Although most general aviation flights rarely last that long, it’s always a good idea to charge the iPad the night before your flight and start with a full battery. In fact, battery drain is about the only issue we’ve had in more than a dozen years of flying with the iPad.

The good news is that charging technology has improved dramatically over the past decade, with the latest hardware allowing you to charge an iPad to 50% in just 30 minutes (instead of 2 hours). Here, we’ll explain how the latest technology works, including a rundown of the basics of electricity and a look at the best charging accessories for pilots to use both at home and in the air.

Electricity 101

The basics of electricity and charging can be overwhelming when you start reading both the technical jargon from an engineer’s perspective and the marketing messages from charger manufacturers. With that in mind, let’s start with some basic electrical terms and what they mean in practice:

Volts (V): Voltage is a measure of the difference in electrical potential between two points in a circuit. It can be compared to the pressure in a garden hose. The higher the voltage, the greater the “push” that drives an electric charge through the circuit.

Takeaway pilot – In your home in the US, the wall outlet voltage is 110V, and all wall chargers are designed to be compatible with that standard. However, most airplane electrical systems range from 14 to 28V. This only matters if you’re using a cigarette lighter plug with a USB charger. The cigarette lighter socket in most airplanes converts the output to a standard 12V, but some older planes may output the full 28V from their electrical system. Know your system and read the fine print on your USB charger to make sure it’s compatible with the higher voltage.

Amps (A): Amperage, or current, is the rate of flow of electric charge. If voltage is the pressure in a hose, then current is the rate of flow of water through it. The greater the current, the more charge flows through the circuit.

Takeaway pilot – In the early days of the iPhone and iPad, we were primarily concerned with the charger’s amperage. The iPhone came with a one-amp charger, and the iPad came with a 2.1-amp charger, which allowed for a faster current flow to charge the iPad’s larger battery. Today’s advanced chargers deliver current much faster, so knowing the charger’s maximum output is more useful than knowing its amperage (most draw no more than 3 amps).

Watts (W): Watts measure power, or the rate at which energy is transferred. If you want to know how much work is being done or how much energy is being used in a given period of time, you would use watts. In the garden hose analogy, watts would be how quickly you could fill a bucket. (Watts are also equal to amps times volts.)

Takeaway pilot – All iPhones and iPads sold in the last 3-4 years support fast charging and can use the latest fast charging technology, which allows them to charge at 25 to 30 watts. With that in mind, look for a charger with at least 30 watts to charge it as efficiently as possible.

More about fast charging (also known as Power Delivery)

Before the iPad, most of us carried around large laptops and used a charger with a large brick attached to one end of the charging cable. These charging cables were inefficient and generated a lot of heat, so they had to be separated from the computer. Fast forward to today, and you’ll find a charger with the same power that’s just a few inches long and plugs directly into a wall outlet. This is largely due to the use of gallium nitride (GaN) in the chargers, which allows for high throughput without generating excessive heat.

The technical term for this latest generation of chargers is “Power Delivery (PD),” although you may also hear it referred to as “fast charging.” Power Delivery is a specification for handling higher power that enables faster charging of many devices, including iPads, over a USB connection. It’s part of the USB-C specifications that enable more reliable and faster charging. Here’s what that means for your iPad:

1. Faster charging:Power Delivery can deliver up to 100W of power, although the actual maximum power will vary depending on the device and charger specifications. For an iPad, which typically requires less power compared to larger devices like laptops, this can still mean significantly faster charging compared to standard USB charging.
2. Intelligent energy management:PD communicates between your device and the charger to negotiate the optimal power level. This ensures your device gets exactly the power it needs, not too little (which would be slow) or too much (which could be harmful).
3. Universal compatibility:While the standard was designed to leverage the capabilities of USB-C, it also retains some level of compatibility with older USB standards. This means you can charge multiple devices with the same charger, although you won’t get the full benefits of PD without USB-C.
4. Single cable solution: With USB-C and Power Delivery, you can use a single cable to charge your iPad, sync data, and even connect other peripherals like external displays. It’s a versatile standard that simplifies the need for multiple cables and connectors.
5. Safe charging: Power Delivery ensures that the charging process is controlled and monitored, so that it adapts to the optimal charging profile for a specific device. This can help extend battery life by avoiding overcharging or other harmful charging practices.

USB Charging Options

One of the few accessories that comes with the iPad is a USB power adapter that charges the device from a wall outlet. It’s worth taking a closer look at the adapter and paying attention to the specs to understand what they mean. The power output of these adapters (measured in watts) has steadily increased over the years, so it can quickly get confusing.

Here’s a quick look at what’s included with each iPad model:

• 5 watts (1 amp): almost all iPhones. Please note that newer iPhone models are no longer sold with a wall charger, only a cable.
• 10 watts (2.1 amps): iPad Air, Air 2, mini 2-4, iPad 2
• 12 watts (2.4 amps): iPad Pro 9.7″, 10.5″, 12.9″ (1st and 2nd generation), iPad Air (3rd generation), iPad mini 5, iPad 5-7
• 18 watts (3 amps): iPad Pro 11″ (1st and 2nd generation), iPad Pro 12.9″ (3rd and 4th generation), iPhone 11 Pro/Pro Max. Please note that this power adapter has a USB-C plug, not the older USB-A plug used on lower-wattage models.
• 20 watts (3 amps): iPad mini 6, iPad 8-9, iPad Air 4-5, iPad Pro 11″ (3rd generation), iPad Pro 12.9″ (5th generation), iPhone 12-14 Pro Max. Also a USB-C connector.

It’s important to understand the specifications of your power adapter, as most USB power adapters for iPhone, Apple Watch, and other devices are rated at 5 watts and 1 amp. The higher-output 2.1/2.4/3 amp charger will charge the large iPad battery faster than a traditional 1 amp adapter (it will take about 4-5 hours to charge a completely depleted iPad battery).

A few notes:

• You can still charge your iPad using a 5W/1A USB power adapter, but it will take longer than 5 hours to fully charge. This is really a last resort.
• The 12, 18, or 20W charger is still safe to use with other USB devices (iPhone, AirPods, etc.) and will not damage them.
• If needed, you can even use a more powerful laptop power adapter (some offer up to 140W) to charge your devices.

For the best charging experience, we recommend the Flight Gear 3-Port Smart Charger, which offers 65W of output and 3 USB ports (2 USB-C and 1 USB-A). The front of the charger features a digital display with a power readout, so you can see exactly how much power your devices are drawing.

You can also use a 12-24V car cigarette lighter charger on the plane to charge your iPad, and this is often the most convenient and cheapest option. We carry two of these chargers with us almost every time we fly. Be careful before purchasing any USB charger, though, because you’ll want to make sure it provides at least 2.1A for optimal charging. This model offers two USB ports, both rated at 3A, and works with both 12V and 24V electrical systems. It also has a built-in screen that displays the battery voltage and current draw — a handy backup. There’s a version with one USB-A port (the standard, larger plug) and one USB-C port (the newer style found in Apple’s latest wall chargers), or with two USB-A ports.

Charging cables

Charging cables are the path our “suppliers” (mentioned above) use to send power to our receivers (the portable devices we use on the plane). There are many cable designs and features available on the market today. To make things easier, we’ve created the graphic below that shows four of the most popular cables.

1. USB-A to Lightning cable (Red) – The most popular charging cable in existence, thanks to the iPhone’s invention and mass production of the Lightning port. Works with iPhones and small to medium iPads. Delivery speed 12 watts.

2. USB-A to USB-C cable (Green) – The first cable option to support Power Delivery (PD). The USB-C side of this cable creates a handshake between devices and if the device “delivering” power has PD capabilities, it will lead to a fast but safe charge. Portable devices equipped with a USB-C port include ADS-B In devices, PJ2+ backup radios, and the Garmin Aera 760. Delivery speed 66 watts.

3. USB-C to Lightning Cable (Blue) – This is the least popular of the four options. It has recently gained popularity as Apple has released new iPhone models with this cable and no wall plug. USB-C charging ports are gaining popularity, so it makes sense for an iPhone (with a Lightning port) to have ability to use them. Delivery speed 20 watts.

4. USB-C to USB-C cable (Purple) – This is the most powerful of the four cables. These are the types of cables used to power laptops or desktops, but they can also be used for our portable USB-C receiving devices. Delivery speed 100 watts.

Like the chargers highlighted above, many cables also feature screens that show charging status. The Flight Gear Smart Charging Cables are a great example, featuring a braided construction for added durability.

iPad Battery Backups

You can also charge your iPad on the go with a portable spare battery. We like the Flight Gear model, which is designed for pilots and has USB-A and USB-C charging ports. The Flight Gear’s 20,000mAh battery lasts for multiple flights and can be charged via micro-USB, USB-C, or Lightning plug — so you don’t have to carry a rare cable to charge it.

It’s our electronic Swiss army knife that we never travel without. They’re also great for planes without electrical or cigarette lighter plugs, and they can be useful outside the cockpit (campers love them).