How much power does an iPad really need? That question is one that our inflight friends are always asking so we set out to get a few answers. In fact, if you have ever noticed that strange message on your iPad: “Not Charging” or your later built device doesn’t seem to raise the charge capacity even with the charger that came with the device, we might have an answer for you.

First, here are couple ground rules:
1. Your new 3rd Generation iPad probably has a built-in 42.5-watt-hour rechargeable lithium-polymer battery. This means that the battery could power (theoretically) a 40 watt light bulb for about an hour.

2. This also means that you have 5 to 6 hours of use without recharging before the battery drains to zero.

3. Since the A.C. battery charger is capable of delivering 10 watts or so, it will take at least 2 to 4 hours to charge it back up. Interestingly, one source told IFExpress that on Generation 3 iPads (and higher), the unit indicates it has reached full charge on the display, but the fact of the matter is it takes an additional hour of charging to actually reach 100%! This also means that if you want to use your iPad under intensive battery usage modes like data or video that work the screen and processor – turn down the brightness.

4. Older computer USB ports may not deliver enough power. The “Not Charging” symbol is a good indication of this situation; however, we have it on good advice that if you turn off your iPad, it will still charge but at a slower rate than normal.

This is also true on an airplane with in-seat power that does not deliver 10 or so watts. To check out our data we stopped by Astronics in Kirkland, WA. for a bit of a refresher and talked to Dennis Markert, Director of Business Development and asked for some information about their latest USB charging solution. Below is a page and table from their playbook describing some tablet charging values and we thought our readers might like to see the information they compiled:

“High Power USB PED Power – Users will be able to power/charge devices with a USB power interface, including iPad and most other tablets, smartphones, media players, games and other handheld devices. Several tablet devices today require significant input power to operate and charge at the same time. Performing certain functions such as reducing screen brightness or placing the device in standby mode can reduce operating consumption; however, it may not be adequate to satisfy the customer requirements. For example, the Generation 3 iPad ships with a 2.1 Amp adapter as standard equipment. The Generation 4 iPad is now shipping with a 2.4 Amp adapter due to an inability to operate and charge simultaneously on the 2.1 Amp adapter. Many of today’s tablets ship with standard adapters in the range of 1.25-2.1Amps. The table below lists most of the common tablets that can be charged from a USB charging port and the power required. The EmPower High Power USB Power Supply system provides more USB power than any other system available today.”

PowerChart

Dennis also showed us their Model 1325 USB Power Supply… and then demonstrated it charging 4 iPads. He told IFExpress: “Our latest cabin USB power supply provides enough power to charge 4 iPads simultaneously …while they are in use. It can deliver up to 2.1 Amps (configuration dependent) at +5 volts from aircraft 115AC power (360 Hz to 800 Hz AC) and, the box is designed to the latest aircraft OEM and FAA requirements.“ However, if you only brought your charger and no USB power cord, Astronics offers their 1315 Seat Power Box that, one airline, is implementing fleet wide, nose-to –tail. Alaska Airlines has chosen Astronics to provide their combined 110VAC and intelligent USB charging system for their entire B737 fleet. This system delivers 110VAC as well as +5 volt DC USB power capable of delivering enough power so passengers can charge, while in use, the latest and most popular portable devices. Stay Charged!