Wiring question

L

LM44S

Junior Member
I have a 38 pickup with the 6 volt charging. From the battery to the single fuse block it reads 6.05 volts. Any reading from there to the ignition switch or to the headlights will be 5.75 volts or so. Should it still read 6.05 or is that a normal voltage drop after going through a switch and the varous connectors? I am trying to get the maximum voltage to the headlights, thinking they would be the brightest at 6 volts? I am thinking the system should read 6 volts any where it is tested and must have a ground problem somewhere?
 
thats not much of a voltage drop what you need to do is check it running at @ 1000 rpm then you’ll no what your generator is doing you should be at @ 7. 5 volts you only use your headlights when engine is running anyway make this test right at the battery good luck
 
On our 38 DLX coupe, I ran a wire from hot wire on starter selonoid through a fuse to a toggle switch under dash,then to hot terminal on dimmer switch, turn the lights on with original light switch, then flip toggle switch, the lights get brighter
 
Try it this way - turn the headlights on. Set the voltmeter on its lowest setting. One probe on the battery ground post itself, the other on the headlight ground terminal. This shows the voltage drop in the ground system. Then the same on the + pos or hot side of the circuit to headlight terminal.

A voltmeter in parallel across a connection or cable will show the voltage drop as a positive voltage, as it finds an easier path through the voltmeter versus corrosion. About 0.2 volts is the limit on the ground side. Maybe 0.4 volts on the hot side. Very small voltage drops cause large drops in headlight intensity. If the voltage drop is excessive on either side start moving the probe closer together to isolate or eliminate and determine where the defective connection or cable is at.

Whether the generator is running at rated output is a separate issue. It needs to be in spec too, but measure to see the voltage drop itself is within spec. Try it with the RPM spooled up too, either way more than a couple tenths of a volt drop is too much regardless.
 
For the headlights, the biggest gain will be had by using the original switching system to activate two separate relays up near the radiator, which themselves are powered by a 10 gauge wire direct from the starter solenoid. The headlights high and low beams are then served by those two solenoids at full battery voltage. On the ground side, run a ground wire from the headlight sockets direct to the frame, thus bypassing the bucket and the fender to ground.
 
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