measuring USB power bank capacity

Well the problem with cheap in this case is that a cheap charger or li-on bat can damage other gear or be dangerous

As you found out when yr usb charger gave out 12v …

Heres a test of various wall usb chargers

http://www.righto.com/2012/10/a-dozen-usb-chargers-in-lab-apple-is.html?m=1

As you can see the counterfeit ones bought off da intrawebs are just dangerous

A bad power source can destroy the protection circuit on yr iphone battery … Which makes it vulnerable to a KABOOM !!!

I can post up quite a few links of fires, explosions and even deaths from this issue …

Of course itll turn into the usual BPL shietstorm at that point

;)

The 12 V charger was one that plugged into car. Griffin Technologies. A little more expensive than the cheapest. It always put out 12 volts.

The 2200 mAh USB power bank is cheap. Since it's so small it's less likely to catch fire, but I should probably get a better one.