12v
The battery is a 12V car battery.
Yes as long as it is the right voltage: a 6v battery needs a 6v charger; a 12v battery needs a 12v charger. <><><> If you can set the battery charger's output to give either a 6 or a 12 volt output, then you must always remember to set it to 6 volts if you want to use it to charge a 6 volt motorcycle car battery.
Probably...The 6V 40A relay figures out as 240Watts...The same relay at 12V 30A figures out as 360Watts.
Usually 6v, can be 12v.
No, you need at least 12v to charge 12v. Most alternators charge at 13-14 volts.
The same as a 12V relay circuit, except it only needs 6V instead of 12V.
A simple test with a volt meter will give you the answer.
If it is in your car then no, why do you have a 6v battery in your car in the first place it should be a 12v.
using dc-dc converter
It should be 12 volt.
No, you cannot use a 12v halogen bulb with a 6v AC adapter. The voltage of the bulb must match the voltage of the adapter for them to work properly. Using a higher voltage bulb with a lower voltage adapter can cause the bulb to burn out or potentially damage the adapter.