Battery backup USB powered product

I'm not sure I understand the use of this device. Something is providing power to your USB product. If you add backup power to that device, won't that continue to power the USB product? That would be the obvious solution to me.

So for some reason that is not practical and you want to provide power to the USB device even when the host device does not have power. Can you add a powered hub and provide backup power to the hub?

Rick

A design like this should work:

Sorry, not made myself clear. Our product is powered from a wall mounted psu with a 5V micro usb connector. I want the option for customers that require it to put something inline with the psu to provide operation when the mains fails Thanks

At the risk of being obvious, you can get a ~200W/~350VA/~5 minute UPS for less than $50, in single units, retail. That would likely supply

5W for several hours, and you can obviously buy a very much larger UPS if the application requires longer runtimes. You'd have to do some of your own testing - at such low power level, UPS's are particularly inefficient, and will be consuming most of their power running themselves (and nobody really publishes runtime numbers for extremely low loads).

What are your runtime requirements?

There are a zillion devices designed for emergency charging of cellphones. The one I have has a usb male plug on one end for charging and a socket on the other end to charge the phone. Comes with charging cable adapters for various phones.

5V output rated at 700ma. 750mAH lithium battery. iCharge Brand ICD-2503-CU JLRGEAR.COM site seems to be non-existent. MicroUSB might be harder to do without an adapter.

I bought it with the intention of powering microcontroller projects, but never got around to trying it.

1 amp seems like a lot for this type of device if you want long run time.

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Thanks, the problem with these devices is that you usually cannot charge and run the connected device at the same time, or if the battery is flat you cannot run our device until the battery is charged. I have tried a ups but we do not draw enough power for them to recognize anything is connected

At least on larger UPS's, there's often a way of disabling the load detection function. For the very small/inexpensive ones, you'd have to For example, on the smaller APC Back-UPS Pro's (like the 700), you can press the display and mute buttons for a few seconds to toggle the feature. For the very smallest/lowest-end devices, you'll have to research it - a quick look at the bottom of the APC Back-UPS line (ass opposed to the mid-range Back-UPS Pro), doesn't appear to document such a function (which may mean either that it doesn't have it, and is not an issue, or that there's no way to turn it off, which would make those unsuitable).

[...]

Steve,

One suggestion, offered in the spirit of "It ought to work, and you can use it while looking for a better solution":

Connect a second, larger load to the UPS as well.

You can test with a table lamp and various incandescent bulb ratings to see how much load you need to make the UPS switch on when unplugged from the wall, then if you need the lamp back on your desk -- replace it withconnect something else that will draw the same load.

Assuming you still have the UPS you tested with available, this immediately gives you backup power for your device, and takes the pressure off while you research a better long-term solution. (If it takes _all_ the pressure off, it may _become_ your long-term solution; I'll let you decide if that's good or bad. )

Hope it helps...

Frank McKenney

--
  "All my best thoughts were stolen by the ancients."
                             -- Ralph Waldo Emerson