Originally it would have been a 6 volt system.
12 volt
From the factory it will have a 6 volt, positive ground system. However, it is popular to replace the original system with a modern 12v system.
The library
If your 1949 truck is a CHEVY or GMC and it still has the original electrical system, it would be 6 volt, negative ground. If it is a Dodge or a Ford with the oringinal electrical system it would be 6 volt, positive ground.
12 volt batteries if fully charged should show 14.2 volts
The voltage regulator inside the alternator is bad.
All Ford F100's from 1956 forward were 12 volt Negative ground.
The Volt
The Chevy Volt just went into production this year.
Voltage (V)AnswerThere is no base unit for voltage. The volt is a derived unit.
No, you cannot charge an 8 volt battery with a 6 volt charger. The voltage of the charger must match the voltage of the battery.
Yes, the voltage listed on the bulb is the nominal voltage and it will work perfectly on a 120 volt circuit.