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Head unit not charging iPad Answered

Hey All,

In my car i have an after market HU with a usb port that my iPad 3/ iPhone 4s / iPods can connect to. However when my iPad is connected to it is unable to charge. The charging indicator in the iPad has the little lightning bolt going through it, indicating that it is indeed charging however the iPad looses about 7% of its battery every hour. Does anyone have any suggestions on how i can get my iPad to charge through my HU?



Do you have the UH correctly wired so it is receiving the power it needs? Are the USB ports meant to be charging things or only for music and data transfers?

Sounds like the HU isn't supplying enough power to the iPad to charge it and keep up with the power demands while it is running.

The HU is correctly powered, and yes it is meant to charge the attached i-device. However the iPad needs 5v at 2amps I think it is only getting 5v at 500ma or 1000ma. Is there anyway to up the amperage?

The iPad doesn't need 2A to charge. If that where the case then no standard USB connection could charge it. The iPad only needs about 200mA for charging.

Sorry mate, but you are incorrect. The iPad wall charger supplies 5v and 2A, you will find that the vast majority of non mac computers will be unable to charge iPads due to this.

Yes the wall charger offers up to 2A but the iPad doesn't need that much power to charge. It only needs 200mA to enable charging but you won't be able to use it while its trying to charge. At most a typical USB port on a PC/MAC only offers 500mA to a device over USB.

This is from Apple Support about charging.

Charging Tips

The fastest way to charge your iPad is with the included 10W USB Power Adapter. iPad will also charge, although more slowly, when attached to a computer with a high-power USB port (many recent Mac computers) or with an iPhone Power Adapter. When attached to a computer via a standard USB port (most PCs or older Mac computers) iPad will charge, but only when it's in sleep mode. Make sure your computer is on while charging iPad via USB. If iPad is connected to a computer that’s turned off or is in sleep or standby mode, the iPad battery will continue to drain.

Your HU probably doesn't have a high power USB port like the new Macs have. Those high power ports offer about 1A. Most other computers that don't have high power ports only offer 500mA. Like the quote says it is able to charge the iPad but only while its in sleep mode. I suspect your trying to use the iPad while its plugged into the HU and thats why your still seeing the battery drain. The 500mA the HU is probably offering isn't enough to support both charging and use of the device. 

If you know what your doing you can open up the HU and find the voltage regulator that powers the USB ports and replace it with one that can supply more amperage. Other then that there is nothing you can do to get more power through the ports. 

Yes you could create your own split cable and use an outside power source. Such as connecting it to the car's lighter. Its just a matter of getting a good 12V to 5V regulator. A single 7805 can offer up to 1A so if you use 2 of them in parallel you will have up to 2A available to the iPad. Then you will be sure to have enough power to charge and use the iPad.