Battery Packs to Use As a UPS

There are lots of rechargable battery packs sold as portable charging units for cell phones and the like. They come in many shapes and sizes and capacities. But I can't find one that says you can use it like a UPS for a device that is powered from 5 volts via a USB cable.

I have had little luck asking eBay vendors about this so I thought I would ask here. I'm looking for something in the 5 AHr ball park but would consider something larger or smaller. It needs to be powered from a USB cable and supply power to a USB cable. But it needs to supply output power when being charged. The output current should be 1 Amp.

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Rick
Reply to
rickman
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I have an "iSOUND" brand 16,000nAH device, that rund while charging, but they look to be no longer making them. Found on at new egg for $89! That is way more thasn I paid.

These are nice, but function while chatging is an unknown attribute...

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Reply to
DecadentLinuxUserNumeroUno

You could use 4x NiMH cells for 4.8v plus an electronic charging circuit to achieve it, but never seen them for sale.

NT

Reply to
meow2222

If you are looking for a rugged power source that will provide power for long periods of time, why not use e.g., a 6V 5AH SLA (sealed lead acid) battery. Very rugged and reliable, can withstand overcharging and can be recharged with a simple SMPS or a linear power supply, both of which are very easy to design and build.

Reply to
dakupoto

All of the ones that I have personally held in my hand make you choose between charging and discharging; you can't do both at once.

My first thought would be to make one from a DC-DC converter, a 12 V gel cell, and "cigarette lighter" USB adapter. The converter needs to take 5 V and output something like 13.5 V, or whatever you think a good float value for your battery is. It also needs to handle voltage on its output when there is no input voltage - maybe a diode in the converter output would help.

Yes, this uses a huge and heavy battery, compared to alternative chemistries. It also relies on a COTS USB adapter, and the quality of these varies. On the positive (hah) side, having 12 V available may be useful for other devices.

There's no reason you couldn't do something similar with whatever your favorite battery chemistry is. You'd get to roll your own input and output converters. If the device you're powering can work with 4.8 V, you might be able to use 4 NiMH cells and skip the output converter.

A little Googling finds...

This article uses a Maxim DC-DC converter chip to do this job:

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This device lets you charge its battery via a hand crank or via USB. It also has separate "charge" and "discharge" ports. The manual doesn't say anything about not charging and discharging at the same time.

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Standard disclaimers apply: I don't get money or other consideration from any companies mentioned.

Matt Roberds

Reply to
mroberds

SLAs dont last long if overcharged. 13.6-13.8 is good (for 12v battery)

NT

Reply to
meow2222

I assume he means they can be trickle charges indefinitely while many battery types will be damaged by even low currents once fully charged.

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Rick
Reply to
rickman

My twenty buck Samsung will charge while runing, but off the wallwart.

However, USB has come a ways. It puts out alot more current than before. Co uple years ago I saw that when I built a PC for someone. That it actually i dentifies as a higher current cource and that allows the charger to go into the mode where they charge faster.

So actualy, it might be a lack of having USB 3 on the PC. It has to TELL th e adapter to go ahead and pull the power, that way it does not burn out the older PCs. People would get pissed.

I have seen things that when plugged into an olde PC, the PC would bitch th at the USB device pulled too much current. Apparently some of them just do it.

Reply to
jurb6006

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