You cannot make a 6 volt battery into a 12 volt batter, but you can make a 12 volt battery out of two 6 volt batteries. Connect two 6 volts batteries together in series and you have 12 volts. Please define "in series".
Depends on the cell design.
Something like car batteries will be very hard to convert from 12 to 6 volts, as the interconnects between the cells are part of the carrying structure of the battery as a whole.
But something like a Ni-Dc battery will probably be possible to turn from 12 to 6 volts, as that battery is more likely to consist of structurally independent cells in a common housing. The cells can be dismounted from each other and reused in another configuration.
Get a charged 12 volt battery hook 12 volt constant/RED to the + on the battery then ground - it should power up.
Yes, if it is a 12 volt DC fan.
Charge it with a 12 volt battery charger.
No
12 volt
No, a 12 volt charger will overcharge a 8 volt battery and destroy it.
The battery is a 12 volt.
No
Yes, a 12 volt battery will be damaged if charged with a 24 volt charger.
If you are asking the question, can you charge a 6 volt battery with a 12 volt charger, the answer is no.
No, the battery is DC not AC.
A 12 volt battery charger is designed to charge 12 volt batteries.The answer to the Related Question explains how any battery charger works.