Depends on the source. If your source is two 12v batteries in series you attach to the terminals of one battery only. Otherwise, you must drop the voltage by adding resistance to the circuit.
You will have a 12 Volt source with double the charge capacity.
No. The value and polarity are different.
With an appropriately rated DC to DC converter.
can ou step down 36 volts dc to 12 volt dc using batteries
No. You need 12 volt AC to run a 12 volt AC motor, not 12 volt DC.
You will have 24 volts DC.
12 Volts DC
The RV has a 12 Volt DC power supply that operates all the 12 Volt DC items in your RV when your plugged in to 110 V AC.
No, the battery is DC not AC.
Most cars use a 12 volt system. Most cars built before about 1956 used a 6 volt system. Some, very few, use a 24 volt system.
One way in achieving this can be getting a 140 watt solar system. The reason behind this is they take both 12 volts and 24 volts.
Yes if it is a 12 volt DC bulb.