I received today this 12/24V charger to charge a 24V battery, I am charging but where? I measure the voltage it outputs 10.5/18V!.. Such reliability!..

Attention to the Amps written. I bought the biggest brother of the 50A and it only gave 7A (measured with an ammeter).

The specs say:

Power: 300W
Frequency: 50/60Hz
Input Voltage: 155-275V
Output Voltage: 12/24V
Output Current: 40A

The fact that the 40A is misleading is still evident from the calculations...

If the output is 24V at 40A, the power should be at least 29V (charging voltage) x 40 = 1160W without conversion losses from 220V to 24V. With losses, it should draw almost 1.4kW from the socket, not 300W.

At 12V, it should be 40A x 15V (charging voltage) = 600W with zero losses, so around 700W with losses... not 300W. The 300W is only sufficient for 20A (300/15=20) with zero losses, and if the losses are around 20%, then calculate 16A... in practice, not even that because the biggest brother of the 50A gave me only 7A. So it is a product that does not meet its specs and it is wrongly categorized as 40A since it will never deliver that.