3 in 1 Magnetic Charger Adapter, Basevs iPhone Lightning, Android Micro USB, & USB-C Magnetic Chargers to Lightning for iPhone X/8/8 Plus/7/7 Plus Samsung Galaxy Note 8, Motorola Moto Z2 and More by Basevs. After using six iPads to test dozens of models, we can safely say that Anker’s PowerPort 4 is the best wall charger for most phones, tablets, and other USB devices. It costs a little more than Apple’s single-port 12W USB Power Adapter, but the Anker model can push out more than three times as much power and charge four devices at once.

A number of Android tablets are powered through the Micro B USB port but also provide USB Host support through the same port (e.g. Motorola Xoom 2, Acer A510/700). I need to be able to use USB Host support while charging, at the full power the device accepts (or at least sufficient power to keep the tablet from draining under modest use). I have rigged up a system with splitter cables and a powered hub. This works on some devices (HP TouchPad, Archos) but not others (Google/Asus Nexus 7, Coby Kyros). And when it does work, it slow charges (probably at USB 2's 500ma).

How can this problem be solved? Are there any solutions on the market that will solve my problem? I see there are some USB chips by Silego (their Battery Charger ID line) that may solve the problem, but I don't know of any cables, hubs, etc. Ironically, in some of the devices where USB host mode is not officially supported (especially phones) but has been enabled by owner-installed kernel changes, its often been the case (at least initially) that the charge pump to drive 5v out the USB port was either non-existent, or not being enabled.

In those cases, you probably could do at least a USB-current-limit charge - and you nearly had to, as you had to provide an external source of USB bus power for the use of the peripheral. – Jun 29 '12 at 3:24 •. Generally, you are not supposed to charge a device when using it as an USB host. That does not mean that you can't.

Usually the USB PHY circuit and ID pin are interlocked in software with the charging circuit. One problem is that if you enable the charger before connecting the USB cable the charging circuit will load down the Vbus and you will never get a valid Vbus condition.

You can usually fool the charging circuit to do whatever you want by sending commands to the driver. For example, on my Nook Touch, I can charge at 500 mA by doing: echo 500000 > /sys/devices/platform/bq24073/force_current. Normally Android 3.1.4.1 is equipped with USB port and can connect to host, not other way around. The host provides 500mA charging power according to Android Open Accessory Protocol. ADK Accessory is possibly the best way to have connectivity + external power + Accesory sub-device controlled by Android. ( when will we see those ADK oscilloscope DIY projects?) But, you are asking about Android being the host and receiving charging power at the same time, instead of providing it as USB host should.

It is not specced in Android documents. Even if you follow ADK 1.0 and 2.0 (Accessory Development Kit), not all 100% of devices will be able to run your software, because ADK exists since Android 3.1 only. Are you sure that 'micro-USB' connector is actually a host?