1st attempt:
I put on a very old battery without having it connected to the power. At first, nothing turned on. I connected the power, the charger turned on without showing anything. I disconnected it, removed the battery.
2nd attempt:
I put on ANOTHER very old battery without having it connected to the power. At first, nothing turned on. I connected the power, the charger turned on without showing anything. I disconnected it, removed the battery.
3rd attempt:
After ~3 minutes, I put the first battery back in, connected it to the power. I repeated the same process (battery inside, connected to power) and it started charging.

It charges with a very low current, resulting in:
- it is good for the longevity of our batteries
- it takes a very long time to charge them
- it charges (at 4.2V) with a maximum of 300 mA. That means a 2300 mAh battery, including (normal) charging losses, I estimate it will take 2300/300*1.2 = 9.2 hours or 9 hours and 12 minutes.

It does not state anywhere if its "smartness" in charging recognizes differences in lithium or nickel batteries or other types. Pay attention, probably not.
I only use it as an alternative charger if something happens to the regular charger and until I get a replacement charger.

I am satisfied with the purchase.
Note: same comments as with another similar charger that I also bought

I have used it in the past, and recently bought it again because I lost it. Reliable, it works fine. If you have lost the charger of the machine.

Disgrace! It only charged the small battery from a pocket camera out of 3 different batteries! And instead of waiting for 2 hours, I waited for 15. In the end, I bought the other one that I had found on Skroutz and not even on sale anymore!