Charging your iPad—it’s all about the watts

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One of the standout features of the iPad is its long battery life—a fully charged battery should last you about 9-10 hours for everyday tasks like accessing the internet, and 4 to 5 hours when using it in the airplane to navigate. Even though 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, running out of battery power is about the only problem we’ve had in over a dozen years of flying with the iPad.

The good news is that charging technology has improved significantly over the past decade and the latest gear allows you to add a 50% charge to your iPad in just 30 minutes (instead of 2 hours). Here we’re going to explain how the latest technology works, including a review of electricity 101, and review the best charging accessories for pilots to use both at home and in the air.

Electricity 101

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

Volts (V): Voltage is a measure of electric potential difference between two points in a circuit. Think of it like the pressure in a water hose. The higher the voltage, the greater the “push” driving the electric charge through a circuit.

Pilot takeaway – In your home in the U.S., the voltage for your wall outlet is 110 volts and all plug-in wall chargers are designed to be compatible with this standard. Most airplane electrical systems, however, range from 14 to 28v. This really only comes into play when using a cigarette lighter plug with a USB charger. The cigarette lighter port in most airplanes will convert the output down to the standard 12v, but some older airplanes may output the full 28v from the electrical system. Know your system and read the fine print on your USB charger to make sure its compatible with the higher voltage.

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

Pilot takeaway – In the early days of the iPhone and iPad we primarily cared about the amp rating on a charger. The iPhone included a one amp charger, and the iPad included a 2.1 amp charger, to allow for a faster flow of power to charge the iPad’s larger battery. Today’s advanced chargers deliver power at a much faster rate, and as a result, knowing a charger’s max watt output is more useful than knowing its amp output (most draw no more than 3 amps).

Watts (W): Watts measure power, or the rate of energy transfer. If you want to know how much work is being done or how much energy is being used in a certain amount of time, you’ll use watts. In the water hose analogy, watts would represent how quickly you can fill a bucket. (Watts is also equal to amps times volts.)

Pilot takeaway – All iPhones and iPads sold over the past 3 to 4 years support fast charging and can take advantage of the latest fast charging technology, allowing them to charge at rates between 25 and 30 watts. With this in mind, look for a charger that is rated for a minimum of 30 watts to allow you to charge it as efficiently as possible.

More about fast charging (aka Power Delivery)

Prior to the iPad, most of us lugged around bulky laptops and they 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, which is why they had to be separated from the computer. Fast-forward to today and you’ll find a charger rated for the same wattage is just a few inches in size and plugs right into the wall. This is in large part thanks to the use of gallium nitride (GaN) in the chargers, which allows for high wattage throughput without producing excessive heat.

The technical term for this latest generation of chargers is “Power Delivery (PD),” though you’ll also hear it referred to as “fast-charging.” Power Delivery is a specification for handling higher power and allows a range of devices, including iPads, to charge more quickly over a USB connection. It’s a part of the USB-C specifications, which enable more robust and faster charging capabilities. Here’s what it means for your iPad:

  1. Faster Charging: Power Delivery can deliver up to 100W of power, though the actual maximum depends 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. Smart Power Management: PD communicates between the device and the charger to negotiate the optimal power level. This ensures that the device gets exactly the power it needs, neither too little (which would be slow) nor too much (which could be harmful).
  3. Universal Compatibility: Though the standard was designed to take advantage of USB-C’s capabilities, it also maintains some level of compatibility with older USB standards. This means you might be able to charge different devices with the same charger, though without USB-C you won’t get the full benefits of PD.
  4. One Cable Solution: With USB-C and Power Delivery, you can use a single cable to charge your iPad, sync data, and even connect to other peripherals like external displays. It’s a versatile standard that simplifies the need for multiple different cables and connectors.
  5. Safe Charging: Power Delivery ensures that the charging process is controlled and monitored, so it adjusts to the optimal charging profile for your particular device. This can help to prolong the lifespan of your battery by avoiding overcharging or other harmful charging practices.

USB Charging Options

18W iPad charger

Make sure you’re charging your iPad with at least a 10 or 12-watt charger.

One of the few accessories included with the iPad is a USB power adapter, which will charge the device from a wall outlet. It’s worth taking a close look at the adapter and noting 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 rundown of what is included with each iPad model:

  • 5 watts (1 amp): almost all iPhones. Note that newer iPhones do not come with a wall charger anymore, just the cord.
  • 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 gen), iPad Air (3rd gen), iPad mini 5, iPad 5-7
  • 18 watts (3 amps): iPad Pro 11″ (1st and 2nd gen), iPad Pro 12.9″ (3rd and 4th gen), iPhone 11 Pro/Pro Max. Note that this power adapter uses a USB-C connector on the plug instead of the older USB-A plug on the lower-watt models.
  • 20 watts (3 amps): iPad mini 6, iPad 8-9, iPad Air 4-5, iPad Pro 11″ (3rd gen), iPad Pro 12.9″ (5th gen), iPhone 12-14 Pro Max. Also a USB-C connection.

Understanding your power adapter’s specs is important since most iPhone, Apple Watch, and other replacement USB power adapters are typically rated at 5 watts and 1 amp. The higher 2.1/2.4/3 amp charger allows the large battery in the iPad to charge more quickly than when using the traditional 1 amp adapter (it will take around 4-5 hours to charge a completely drained iPad battery).

A couple of notes here:

  • You can still charge an iPad with a 5-watt/1 amp USB power adapter, but it will take longer than 5 hours to fully charge. This is really a last resort.
  • A 12/18/20 watt charger is still safe to use with your other USB devices (iPhone, AirPods, etc.) and will not damage them.
  • You can even use your laptop’s higher-wattage power adapter (some are rated up to 140W) to charge your devices if needed.

For the ultimate 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 includes a digital display with a wattage readout, allowing you to see exactly how much power your devices are drawing.

You can also use a 12-24V cigarette lighter charger in your airplane to charge your iPad, and this is often the most convenient and affordable option. We carry two of these pretty much every time we fly. Pay close attention before just buying any USB charger though, as you’ll want to make sure it provides at least 2.1 amps for optimum charging. This model offers two USB ports, both rated at 3 amps, and works on both 12V and 24V electrical systems. It also has a built-in screen that displays battery voltage and amp 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 on the latest Apple wall chargers), or one with dual USB-A ports.

Charging Cables

Charging cables are the path through which our “providers” (mentioned above) move electricity to our receivers (handheld devices we use on the flight deck). There are plenty of cable designs and features out on the market today. For the sake of simplicity, we’ve created a graphic below that will convey the four most common cables out there.

1. USB-A to Lightning Cable (Red) – Most popular charging cable out there thanks to the iPhone inventing and mass producing the Lightning port. Works with iPhones and small to medium-sized iPads. 12-watt delivery speed.

2. USB-A to USB-C Cable (Green) – First cable option to allow Power Delivery (PD). The USB-C side of this cable creates a handshake between the devices and if the power “providing” device has PD capabilities, this will lead to a fast yet safe charge. USB-C port-equipped handhelds include ADS-B In devices, the PJ2+ backup radio, and the Garmin Aera 760. 66-watt delivery speed.

3. USB-C to Lightning Cable (Blue) – This is the least popular cable of the four options. It’s gained popularity recently with Apple releasing new iPhones with just this cable and not providing the wall plug. USB-C charging ports are growing in popularity so it makes sense for an iPhone (with a Lightning in port) to have the Flight Gear smart charging cablesability to use them. 20-watt delivery speed. 

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 desktop computers, yet they can also be used for our USB-C receiving handhelds. 100 watts delivery speed.

Like the chargers highlighted above, many cables also include screens to show charging status. The Flight Gear smart charging cables are a great example and incorporate a braided design for extra durability.

iPad battery backups

You can also charge the iPad when on the go with a portable backup battery. We like the Flight Gear model, which is designed for pilots and feature both USB-A and USB-C charging ports. The Flight Gear Battery Pack (20,000 mAh) will last for multiple flights and can be recharged with a micro-USB, USB-C, or Lightning plug—so you don’t have to bring a rare cable just to keep it charged.

It’s our electronic Swiss Army knife, and we never travel without it. These are also great for airplanes without an electrical system or a cigarette lighter plug, and they can also be useful outside the cockpit too (campers love them).

1 reply
  1. Peter
    Peter says:

    Overall, great way off getting people to think about the charger they need.

    I’d probably suggest a little change in the hose analogies.
    Volts might be a garden hose for 110v and a fire hose for 220v with both hoses tossed in a lake.
    Amps would be how big of a pump and how much water is being sucked through the hoses.
    Watts still works with the potential through the garden hose or firehose x how big the pump is and how much water it can suck through the hose.

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