Small 5V supply from AA batteries

[ebclr]

0.39 USD

http://www.aliexpress.com/item/Free-Shipping-1PCS-0-9V-5V-to-5V-600MA-USB-Output-charger-step-up-Power-Module/32701204969.html?spm=2114.30010308.3.2.pTvogs&ws_ab_test=searchweb201556_0,searchweb201602_3_10057_10056_10065_10037_10055_10054_301_10059_10058_10032_10017_107_10060_10061_10052_414_10062_10053_10050_10051,searchweb201603_2&btsid=75d06c0a-80bb-4d90-80c8-dfc14269da63

[ez24]

0.39 USD

This is the cheapest thing I have seen with free shipping.

[ebclr]

I have one, if you want i can do some tests you may want

[ebclr]

50W for sure is typo, 1A 5V = 5W

[sleemanj]

50W output capacity sounds impressive. Colour me skeptical.

They are fixed 5v output and can do up to about 600mA tops, I'll leave you to do the math :-)

They do work OK and are good for low current demands from even a single AA cell (or parallel cells) as they will run down to a very low voltage.

[Keysight DanielBogdanoff]

Could you just use a usb battery pack?

This.

[ez24]

Could you just use a usb battery pack?

This.

Are you sure you don't mean "that"

[Zero999]

Any voltage regulator uses extra energy. It's true that a linear regulator is less efficient than a switched mode but it still uses more energy.

[tszaboo]

Could you just use a usb battery pack?

This.

A lot of the battery packs are designed to charge phones. If you dont load them with, say 50mA, they shut down. Forget using the cheap and excellent Xiaomi power bank to run an Arduino for example. Others use DC-DC converters with quiescent current higher than your actual load.

[mikeselectricstuff]

Could you just use a usb battery pack?

This.

A lot of the battery packs are designed to charge phones. If you dont load them with, say 50mA, they shut down. Forget using the cheap and excellent Xiaomi power bank to run an Arduino for example. Others use DC-DC converters with quiescent current higher than your actual load.

That's a possible issue,but as a quick & cheap solution it's worth a try. I've used them for various random stuff and I don't recall having switch-off issues above about 50ma. Ymmv of course.

[Chalcogenide]

I have a few of them. When you remove the built-in LED, the quiescent current is <0.5mA which is still quite significant. It also increases fairly rapidly when the voltage gets lower than a couple of volts. BTW, the USB connector is awful quality, but for the price I don't even know how can they afford to have one.