iPad USB Charging Monitor/Activator

5-1-10

If you have an Apple iPad, you have undoubtedly had questions about how fast and even if your iPad is charging. As a matter of fact, some perfectly good USB ports will never charge the iPad.

If you have a brand new Apple MacBook Pro or any Mac, those USB ports may or may not charge your iPad. Even if it does, the indicator on the iPad may or may not tell you that it’s charging.

And in all cases, the iPad charge indicator will not tell you how fast it’s charging (how much charging current is being delivered to the internal battery). So, you don’t know how long it’s going to take to completely recharge your iPad. The time required to recharge is dependent on the level of discharge [current input from the USB port to the iPad?].

We have designed a simple device that not only ‘turns on’ USB chargers but also gives a visual indication of how fast your iPad is charging.

This device also works on all Apple iPhones, iPod Touch, 30-pin iPods.

Background
USB ports are spec’d to a “number of loads” they can support. Most Macs support five loads which is 500mA. Some of the newer computers will supply “7 loads” or 700mA. The USB 3.0 standard spec is 7 load units.

The QuickerTek device has four LEDs and circuitry that measures and displays the
charging status of the Apple iPad. The LEDs show charging input from 100mA to greater than 1 Amp in four steps - indicating the loads that most USB ports supply.

For example, if approximately 100mA is suppled (1 load), only the first LED glows. If 4 to 5 loads are supplied, then the first and second LEDs glow. If 7 loads are supported then 3 out of 4 LEDs are activated.

An exception to this guideline is the MacBook Air which supplies 700mA. Because the external CD/DVD drive requires more than the typical 500mA from laptop USB ports.

Even if the computer’s USB port is capable of suppling enough current to charge the iPad, this does not guarantee that the charging indicator on the iPad is on. QuickerTek’s LEDs make up for this.

The USB charger supplied with the iPad is able to supply 2000mA at 5.1vdc. The USB standard is a max of 5.25vdc. However, to get the iPad to actually draw that much current, it has to be fully discharged. So the question remains, “how fast is my iPad charging?“

If you have an automobile or airplane USB charger you want to use - some will work some will not. QuickerTek’s device monitors, as well as turns on, all of these chargers.

Our iPad charger interface device was born out of necessity - we have also designed external batteries and a solar charger for the iPad. This clever little interface guarantees that not only will the USB port charge - but it also displays the level at which the charge is taking place.