50’s Chevy Truck Weird Battery Issue?

[Gary]

Hey guys it’s seems like it’s been ages since I’ve posted here…have had quite a lot of stuff going on.

In any case I’ve been having a weird issue with one of the trucks, the 1955 and I can’t seem to pin it down.

I just put a new battery in the truck after I found the old one had a dead cell and was draining every single night to nothing.

The truck has not been run in 3 weeks and the new battery did not have enough juice to start the truck, I got a few cranks out of it and thats it.

I’m ashamed to say I’m stumped as a technician…really but to give an idea:

1. The truck has NO fusebox…it was an option in the 50s
2. No directionals, also an option in the 50s
3. The starter does not have an electrical solenoid…it is foot operated mechanical On/Off contact switch
4. No Radio..at all again a 50s option
5. The only things electrical on it are the starters contacts, the generator, headlights, and the ignition system which is of the breaker point persuasion.

In other words there is nothing that can draw on the system that I wouldn’t know about. Pulling fuses to test for parasitic draw doesn’t apply and I know that a short is impossible because I would have found it easily. Headlights are the only thing that would draw when the key is off, and they don’t. The ignition system is open when the key is in the off position as well as I’ve tested on either end of the coil.

Is it possible for the battery to lose that much charge sitting for three weeks without the engine being run?

Topic

[Richard Kirshy]

In a vehicle that old:
I would be looking for a possible short in the generator or the starter circuit.

You can still do a parasitic draw test, but in your situation instead of pulling fuses you’ll need to start disconnecting electrical connections
IE. generator power feed, power feed to the starter switch then starter motor.

Is it possible for the battery to lose that much charge sitting for three weeks without the engine being run?
If the battery wasn’t fully charged to begin with.

If I remember correctly:
Unlike a alternator, which replaces what the vehicle uses from the battery.
A generator system actually supplies power to the vehicles electrical system and I assume some type of recharging circuit to replenish the battery, which may be at fault for a discharge condition.

[Gary]

[quote=”nightflyr” post=167930]In a vehicle that old:
I would be looking for a possible short in the generator or the starter circuit.

You can still do a parasitic draw test, but in your situation instead of pulling fuses you’ll need to start disconnecting electrical connections
IE. generator power feed, power feed to the starter switch then starter motor.

Is it possible for the battery to lose that much charge sitting for three weeks without the engine being run?
If the battery wasn’t fully charged to begin with.

If I remember correctly:
Unlike a alternator, which replaces what the vehicle uses from the battery.
A generator system actually supplies power to the vehicles electrical system and I assume some type of recharging circuit to replenish the battery, which may be at fault for a discharge condition.[/quote]

I’ve confirmed it’s not within the starting circuit, as I’ve put my multimeter on it and when my foot is not on the pedal, there is no voltage going through it.
Actually, the button that is pushed by the foot rod is untouched and when depressed, move voltage through. So it is functioning as normal(this is the original starter)
As far as the generator is concerned, it is the original generator and it’s power is routed through a voltage regulator(which serves as a distribution center) on the firewall(also original) to the ignition system and ammeter. There is NO direct connection to the battery.
The Battery is connected to the starter and ground, that’s it.
The battery is also brand new, it was fully charged.
I believe you are correct, the generator powers the vehicle and the battery simply starts it. After starting, the battery has no hand in the matter.

Foot on Starter>Crank Engine>Cranks Generator>Key Closes Ignition Circuit>Starts Ignition>Engine Firing>Starter Circuit Disengage

So in theory, the battery gets the excess charge from ground, as the generator is grounded, not directly charged.

It still leaves the mystery however.

[Richard Kirshy]

I wonder if perhaps there may be an issue with one of the shunt windings:

Without specifics … here is a 1950-51 wiring diagram

Attachments:

• CompleteWiringDiagramof1950-1951ChevroletPickupTruck.jpg

[Gary]

[quote=”nightflyr” post=167938]I wonder if perhaps there may be an issue with one of the shunt windings:

Without specifics … here is a 1950-51 wiring diagram

[/quote]

Even though that diagram is for the older 6 volt system(GM switched to 12 volt in 1955) is is still very similar to how the truck is wired, similar enough to use.

By the shunt windings, are you talking about the ones inside the generator?

[Richard Kirshy]

Though not specific to yours..
I assume the basics are the same

Attachments:

• GeneratorWiring.jpg

[Gary]

[quote=”nightflyr” post=167941]Though not specific to yours..
I assume the basics are the same

[/quote]
I will have to look into that. The regulator box that contains those components is also original to the truck so it’s entirely possible.

[Brian]

I’ve bought trucks newer than yours that had sat for about a decade, had the same issue. For me, it was the insulation in the wires leading to the tail lights in the side of the bed. The bare wires rubbed the grounded bed and ran the battery dead every night.

[Author]

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