Jay H
servicedriven.org
Just a word of caution USB charging is weird.
Strange things happen with the dedicated charging port. With a PC all devices are effectively and safely limited to 500ma. Its certain devices on charge ports that do odd things.
I have a droid bionic and it does not like certain charge ports.
I have an old computer power supply that supplies 12V and runs my fridge when it is out of the vehicle and sitting in the garage. I added a usb sockett to the 5V rail but with a simple 150 ohm resistor across the data pins ( 2 center pins of a standard usb plug) it goes haywire. The touch screen quits being responsive and the devise gets warm. Not good but all is well when it is unplugged again.
Same thing with the set up I use for off grid I have charging when backpacking. I have a very nice lithium ion 4 cell pack that is 14.4v nominal.
I was under the impression that 150 ohms across that data pins tells a devise that it is connected to a charge port capable of supplying up to 1A.
Of course in true apple form my fiances Ipad pulls 2A from my the above mentioned power supply.
One would think the devise would handle the charge and limit t current, this is not always the case which is annoying. I like being able to charge off the fridge power supply but its a 30A 5V rail and my phone pulls more current that it should. I dont like to fast charge because you dont get a full charge and it puts more wear on the battery.
Makes me wonder if my droid bionic is pulling 2.1A from the 1A rated USB charge socket on my inverter. I sure hope not.
What I am wondering is if USB chage ports must be current limiting rather than the connected devise being current limiting. Obviously some current limiting is happening or my 30A 5v rail would turn devices into boiling liquids.
I want my DC-DC step down converter I use with the lithium pack in the back country to limit to 2A or less other wise the IC (integrated circuit) that is rated to 3A no cooling 10A active cooling will get hot and waste precious battery capacity. The lower I push that IC the happier it is.
Is there is a way to simply tell a devise no more than 2A from a charge port based on a logic, voltage or resistance across the data pins?
Strange things happen with the dedicated charging port. With a PC all devices are effectively and safely limited to 500ma. Its certain devices on charge ports that do odd things.
I have a droid bionic and it does not like certain charge ports.
I have an old computer power supply that supplies 12V and runs my fridge when it is out of the vehicle and sitting in the garage. I added a usb sockett to the 5V rail but with a simple 150 ohm resistor across the data pins ( 2 center pins of a standard usb plug) it goes haywire. The touch screen quits being responsive and the devise gets warm. Not good but all is well when it is unplugged again.
Same thing with the set up I use for off grid I have charging when backpacking. I have a very nice lithium ion 4 cell pack that is 14.4v nominal.
I was under the impression that 150 ohms across that data pins tells a devise that it is connected to a charge port capable of supplying up to 1A.
Of course in true apple form my fiances Ipad pulls 2A from my the above mentioned power supply.
One would think the devise would handle the charge and limit t current, this is not always the case which is annoying. I like being able to charge off the fridge power supply but its a 30A 5V rail and my phone pulls more current that it should. I dont like to fast charge because you dont get a full charge and it puts more wear on the battery.
Makes me wonder if my droid bionic is pulling 2.1A from the 1A rated USB charge socket on my inverter. I sure hope not.
What I am wondering is if USB chage ports must be current limiting rather than the connected devise being current limiting. Obviously some current limiting is happening or my 30A 5v rail would turn devices into boiling liquids.
I want my DC-DC step down converter I use with the lithium pack in the back country to limit to 2A or less other wise the IC (integrated circuit) that is rated to 3A no cooling 10A active cooling will get hot and waste precious battery capacity. The lower I push that IC the happier it is.
Is there is a way to simply tell a devise no more than 2A from a charge port based on a logic, voltage or resistance across the data pins?
