You may have a Delco Light Plant and have decided that it is time to determine exactly what it is.  This can be done with part fact and part guesswork.  First examine your light plant.  If you are lucky you can identify your light plant by model number identification, which may be found on or near the switchboard in the form of a paper or painted wiring diagram or simply a paint-stamped identification plate.  The model number was always provided to the consumer on their purchase agreement (form 203) and with their instruction book, which by the way almost never survives as long as the actual Delco Light Plant itself.

Before July, 1929 models were numbered simply to indicate the output in watts of the generator.  If you have a 600 series light plant, it has a 600 watt generator and so on.

After July, 1929 model numbers became more informative.  For example if you have a model 6AB3, you have a 600 watt light plant with automatic battery charging, 32 volts DC.  Here is how you decipher these model number codes:

1.    The first number indicates in hundreds of watts the output of the generator.

2.    The next letter(s) indicates the type of light plant.
    A = Automatic
    B = Battery Charging
    C = Combination
    FA = Fully Automatic
    G = Generator Only
    H = Hand Crank
    K = Kerosene
    M = Manually Operated
    W = Water Cooled (Marine Only)

3.    The final number following the letter(s) indicated voltage:
    1 = 110 Volt
    3 = 32 Volt

    4.    There may or may not be another number or letters after the voltage indication.  These were added to indicate the type of battery that was to be used with that particular light plant:
        3 = 3 Plate Battery
        7 = 7 Plate Battery
        ICG9 = 9 Plate Ironclad Battery
        ICG11 = 11 Plate Ironclad Battery