Haunted Car


#1

Is it possible the car was in gear?


#2

Is this yet another Stream of Consciousness post, or is it in regard to the recent Puzzler?

If it is the latter, the “solution” to the Puzzler was that the car had been left in gear.


#3

So sorry, it should have been “The Creepy Case of the Haunted Car”.


#4

I still have no idea what that’s about. If its from the show, these days I don’t get a chance to listen more often than not. I think a lot of people here don’t actually listen to the show regularly


#5

Sorry!


#6

Strangely enough I had the same type of thing happen to me. I bought an old car (53 Caddy) and had it towed to by shop (I love to restore old cars/machinery). The car was accidently left in gear (actually the fork was bent so we couldnt get it into Neutral). Brought it home and all the way home the headlights were on, not very bright, but on the same.

I answered the puzzler but was not chosen to win :-(.


#7

In the puzzler, the battery was already disconnected. In older cars that used a generator, didn’t the battery have to be connected to complete the circuit?


#8

That occurred to me too, but if that’s the case the generator would always be charging the battery. See the first diagram on this page:

http://www.rowand.net/Shop/Tech/AlternatorGeneratorTheory.htm


#9

My thoughts as well ref the battery. In the old cars, they also had a regulator which. I think controlled the flow of generated electricity to the battery…when the battery was charged then the generator would power the spark lights etc. Never thought about it much when working on cars with generators…but maybe when the battery is disconnected it is the same as the regulator switching to power the car from the generator??? Any toughs on this?


#10

See the first diagram on this page:

http://www.rowand.net/Shop/Tech/AlternatorGeneratorTheory.htm


#11

The diagram doesn’t show the connection for lights, only the regulator, generator and battery. I know in my old 58 Chevy that if you disconnected the battery cable the engine would die; not so in my 69 Cuda. It had an alternator.

My understanding, and I’m not an electrician, is that in older cars, everything ran off the battery and the generator was used to recharge it. In new cars the alternator provided the electricity for all of the components, including the battery, which was used only to start the car.

I still believe that in the haunted car, if the battery cable was disconnected, even with the car in gear the headlights would not come on.

Rich


#12

So you can only push-start a car with an alternator? (of course that may only be a solution for a starter problem, not a battery problem)

Why did you disconnect the battery cable with the engine running?


#13

The following is true for both generators and alternators:
The gen/alt is wired in parallel with the battery. If the gen/alt is producing no power all current to the car?s electrical system is provided by the battery. When the gen/alt begins producing enough power its voltage is regulated to be higher than the battery. Current from the gen/alt now flows to the car?s electrical system and since the gen/alt voltage is higher than the battery voltage current flows backward through the battery charging it. The regulator (plus diodes in an alternator) prevents current from flowing back through the gen/alt to ground and draining the battery. If the gen/alt isn?t producing enough voltage current will flow from the battery.

The haunted car scenario works because generators, unlike alternators, have permanent magnets to establish the magnet field the armature turns in. Generators can self start. Alternators rely on electromagnets to generate the magnetic field and need a small amount of power from the battery to start producing electricity.
You can?t push start a car with an alternator and a completely dead battery.


#14

So the lights are connected at the voltage regulator and not at the battery terminal? Power will flow to the headlights even if the battery is not in the circuit? The car is in gear, which turns the engine, which turns the generator, which sends power to the voltage regulator where the headlights are connected.

Sorry, just trying to understand.


#15

So you can only push-start a car with an alternator?
I would never push start a car. It’s dangerous. But if I were to take the chance, I’d be sure to have the battery cables connected.

Why did you disconnect the battery cable with the engine running?
Curiosity


#16

There are several ways it can be wired but the positive battery cable is common to the regulator output, the car?s fuse block, and the starter. Said another way, current flows from the generator through the regulator to the car?s positive supply.
Hope that helps


#17

You could disconnect the battery and push-start an old car equipped with a generator. However, you might burn up the regulator contacts. Popular Science had a monthly feature called “Tales from the Model Garage” with its proprietor Gus Wilson. These stories ran sometime from the mid 1920s through 1970. In one story, Gus saw someone steal the battery from his car. Gus’s car was conveniently parked on a slope, so he was able to roll down the slope and start the car. The car was a manual transmission.


#18

I figured that if it wasn’t the battery the only other possibility was the generator. Thanks for fleshing it out.


#19

Yes, thank you for your explanation.


#20

“I know in my old 58 Chevy that if you disconnected the battery cable the engine would die”;

On a generator equipped car,as was your 1958 Chevrolet, the generator had to be turning above the idle speed to produce, while an alternator will produce power at idle. Had you brought the rpms of your Chevrolet engine up above the idle speed where the generator is actually generating power, your 1958 Chevrolet engine would not have died.