Hi everyone. I'm new to forums and midi things in general (I'm old school analogue synth). I have a simple query.
I have just bought a UA-25 with Cakewalk. The software I will install later but it's the hardware I wish to ask about. It will provide phantom power to a pair of microphones and is USB powered itself ... rather than carting a laptop around, does anyone know if I can use one of these USB Portable Power Packs (usually for charging mobile phones) and connect a USB lead to provide the 5v? This will allow me to have two 48v mics plugged into the UA-25 which is then plugged into my minidisc recorder via optical ... all battery, all fairly lightweight ... or is this just silly? I want portability with decent mics and silence for power. Laptop fans always kick in when you don't want them to. There'll be no mains where I'm recording (I'm off to remote country France in 4 days, no internet, no wireless, no noise and no translation :(  )
As I said, I'm old school trying to out digital the digital world in a Heath Robinson way.
Thanks for your time

Oh ... and I may not be able to respond to any replies due to isolation so I thank you in advance. Don't you just love being controlled by technology? :)

Depends on the amperage the charger delivers, which may be inadequate. Check the requirements of the UA-25 in the documentation and compare that to the charger unit. I would not be surprised if the power pack puts out a low current, which is fine for charging a cell phone but might not be sufficient to drive the audio interface. 
 
Another possible concern is that the DC output from the charger may not be well-filtered, potentially resulting in hum or buzzing in your recording.

You should actually think about investing in portable recorder. I have the Tascam DR 40 and I use it for a zillion different things now. Mine is 4 track and was around $150, My band mate bought the 2 track model for $90. The mikes are excellent and talk about easy to use. Mine is good for almost 20 hours on a set of batteries. It will also run on USB power.
 
And just a note about your idea, Some mikes need a lot more power ( phantom) than USB can deliver. All electronic devices need a combination of both Voltage and Amperage to function properly. Most of those USB power packs are very low amperage. I know , I fried my GPS a few weeks ago using a small Cigarette to USB adapter. Reading the amperage on both  the original and the mini adaptor thing latter on I figured out I grossly underpowered the GPS and it died.    I have a couple of condensers that would not work with a M audio interface I had that was USB bus powered. I had to use the wall wart to get it to work. Otherwise the sound was distorted.

Thanks Bitflipper - the cell based chargers I've looked at are tiny so I think you'd be correct with them dropping out. I don't want to lug a car battery with me but then again it's pointless buying into a 10 minute recording unit. I'd look at self powered condenser mics but apparently the self-noise can ruin a recording - so adding the dc hum ... yeah, off to a bad start.  I'm wanting to record natural ambient silence ...
I shall try to find the specs and do a lot of homework before I leave.

I think I'm stuck in the dark ages ... I have a dozen analogue synths that don't talk to the laptop and the one that does (the Korg) has a latency problem (hence getting a UA-25.  I've not used midi before, never recorded in anger and had this madcap thought "I need to record something in France" ... so I've packed the car with Korg, laptop, sampler, minidisc, cables but no mics as yet ... I've left Ireland and am picking up what I can find in the UK. I think the fully digital recording must be the way forward guys - I suppose it interfaces better, records cleaner and is easier to use. Once done, I can then use the UA-25 to create the final result. Thanks for that ... my mind is a lot clearer.

Sounds like a grand adventure. Good luck to you!

Many thanks. I've no idea why I want to do it but once it's out of the way, there'll be something else to mess about doing. Glad to have the UA-25 now ... hopefully I can get a bit more up to date ... all my friends left me behind years ago.