AA USB travel chargers - any good? What's the real capacity?

[r_southampton]

Hello,
I'm thinking of buying a mini-usb AA (1, 2 or 4, to be decided) travel charger for an Orbit 2.

There's plenty of cheap stuff on Ebay or Amazon (and elsewhere), but If anyone has used them, I'd like to know

A) do you think the output is regulated enough to be suitable for safely charging my Orbit.

B) How much power is lost? For example a 1.2V 2500 mAH AA battery, should (if the rating is correct) should have nearly 2.7 WHour capacity (1.2*2.5), so that should roughly half fill an 1350mAH (3.7x1.35 = 4.8 WHour) Orbit 2, even allowing for some power loss.
Does this match your experience.

Perhaps it's easier just to carry a spare orbit battery, but AA's are so useful, and you can find them anywhere.

[Pull9Gs]

Ive been tempted by these, but never heard good enough reviews to buy one so am interested to know how you get on.

[PaulusUK]

I've been looking at a Li-ion pack on evilbay - 2600mAh in a unit the same shape as a PPC phone but just a little smaller. Seems like it will fit on the back of my m700 with some velcro (or rubber band!) - so allowing extended GPS use outdoors.

My questions are similar - are external packs worth it, and do they keep the phone charged and do they fully charge a dead phone?

BTW, I'm also looking at a solar charger currently on offer at maplins (http://www.maplin.co.uk/Module.aspx?TabID=1&ModuleNo=223748&doy=27m6) . Its £9.99 (£20 off ?) and will hold and charge 5 AAA batteries. Solar chargers like this generally get crap reviews, but the seemingly good thing about this one is its rated at 1w, which is more than similar ones which I've seen

[Just about right]

Hello,
I'm thinking of buying a mini-usb AA (1, 2 or 4, to be decided) travel charger for an Orbit 2.

There's plenty of cheap stuff on Ebay or Amazon (and elsewhere), but If anyone has used them, I'd like to know

A) do you think the output is regulated enough to be suitable for safely charging my Orbit.

B) How much power is lost? For example a 1.2V 2500 mAH AA battery, should (if the rating is correct) should have nearly 2.7 WHour capacity (1.2*2.5), so that should roughly half fill an 1350mAH (3.7x1.35 = 4.8 WHour) Orbit 2, even allowing for some power loss.
Does this match your experience.

Perhaps it's easier just to carry a spare orbit battery, but AA's are so useful, and you can find them anywhere.

I have several of the 4 AA usb type for my PPC and WM devices. I haven't had any issues with it damaging the device, but I'm careful as to what the power rating is on the device. I don't going over by 1watt but anything else I don't risk it. My devices require 5watt to charge, so the extra watt doesn't hurt anything. It's been a life saver on long trips and when in a pinch to need to charge.