I have a new Thomson Battery Charger bcm 1220, but it does not give output voltage to charge battery, what can it be the problem?

I have a New Thomson Battery charger which does not give output Voltage before Connecting the losd (Battery to charge) why?

It has Reverse polarity protection.

That means it has to "see" voltage of the correct polarity from the battery it is connected to, before the charger power output is connected to the output terminals.

It's a common feature on better quality chargers.

(In the simplest form, it can be just a relay coil with a diode in series, across the output terminals, with the contacts connecting the charge circuit to the output terminals).

Thank you for the answer. I will connect to the load and see.
Thank you again.

And read its manual. A battery rescued from months abandoned discharged by the backyard weeds is not acceptable to charge, it is dead.