Didier Stevens

I tested a small powerbank that I have, and it’s very inefficient.

It takes 10.07 Wh to charge:

And it delivers 5.95 Wh when I discharge it (5V at 0.250 mA).

So I only got 59% back of the energy I put in.

This powerbank is quite old, it might have become so inefficient over the years. Google searches tell me that you should get at least 85% efficiency.

Although this powerbank still works fine, and his very handy to me because of its small form factor, I’ll see if I can get a more efficient one with a similar form factor.

I made a mistake and destroyed my old multimeter.

It’s a 30+ year old multimeter, and it had become very dirty because of all the dust it collected while I used it in a home renovation project, years ago. It was still functional, so I used it for years like that.

But recently, after discovering YouTube “restoration videos”, I got the idea to open it up and clean it.

The result was very good. Until I used it the first time to measure a 230V cable. Then there was a big flash inside the casing, and all the lights went out.

This is how it looks now (notice the black soot marks on the orange plastic):

And the burned diodes:

What went wrong? The meter also has aluminum foil to shield the electronics:

And I was not careful enough when I put it back, and it shorted the 2 connectors: