Generator Cutoff relay

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BarnesvilleT
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Generator Cutoff relay

Post by BarnesvilleT » Mon Jan 30, 2023 1:15 pm

Can anyone shed some light on whether to use the original one I have or switch over to a solid state one.
A description of the original one could result in generator failure and the solid state ones sound like they
are more reliable. I found them on Snyders web site and the cost is a lot less that replacing a generator
if the relay gets stuck. Any thoughts would be appreciated.

Bill

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RajoRacer
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Re: Generator Cutoff relay

Post by RajoRacer » Mon Jan 30, 2023 1:19 pm

Since the true voltage regulators haven't been available for some time now, the diode cutout would be the safest bet - IMO !


randahl
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Re: Generator Cutoff relay

Post by randahl » Mon Jan 30, 2023 1:22 pm

I got a solid state from Smith and Jones about a year ago. You might try them. Probably doesn't help but there ya go.

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Flivver
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Re: Generator Cutoff relay

Post by Flivver » Mon Jan 30, 2023 10:52 pm

If you have questions about the original cut-outs, my videos might help. https://youtube.com/playlist?list=PLP_q ... Wo-GxTmDBD
Screenshot_2023-01-30-22-50-54-55_f9ee0578fe1cc94de7482bd41accb329.jpg

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Charlie B in N.J.
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Re: Generator Cutoff relay

Post by Charlie B in N.J. » Tue Jan 31, 2023 9:14 am

Off the top of my head why isn't the T wired so that power just cuts off when the engine is shut down eliminating the relay totally.
Forget everything you thought you knew.

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Mark Gregush
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Re: Generator Cutoff relay

Post by Mark Gregush » Tue Jan 31, 2023 10:00 am

I have used an older replacement cutout for years and have had very little issues with it. I am not talking about the newer reproductions, mine I am pretty sure is a Standard. Most all of the more modern reproductions of the point type cutouts are ok for short trips or lite driving, the windings inside are not all that good. The current solid-state ones listed in the catalogs are just diode type. Most of what I have read seems to point to them doing the job.
I have not done a conversion to diode for my car yet, but given the choice, I might be inclined to search out a good American made cutout from maybe the 70's back. Failing to find one of those, I would not hesitate to use the diode type. :D
I know the voices aren't real but damn they have some good ideas! :shock:

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TXGOAT2
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Re: Generator Cutoff relay

Post by TXGOAT2 » Tue Jan 31, 2023 11:23 am

Why a cutout?
An automatic cutout device is needed because the generator does not function at low engine speeds, and instead will actually draw power from the battery. If the generator is connected while the engine is stopped or while it is being cranked, the generator will draw a very heavy current from the battery.

A stock type cutout needs to be adjusted correctly to work as it should and to last. A cutout that is set too low will tend to cycle frequently, which will shorten its life. One that is set too high will not allow the generator to charge at lower engine speeds. A good original-type cutout or quality repro is a very durable device if adjusted properly and not abused.


Jerry VanOoteghem
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Re: Generator Cutoff relay

Post by Jerry VanOoteghem » Tue Jan 31, 2023 11:30 am

TXGOAT2 wrote:
Tue Jan 31, 2023 11:23 am
Why a cutout?
An automatic cutout device is needed because the generator does not function at low engine speeds, and instead will actually draw power from the battery. If the generator is connected while the engine is stopped or while it is being cranked, the generator will draw a very heavy current from the battery.

A stock type cutout needs to be adjusted correctly to work as it should and to last. A cutout that is set too low will tend to cycle frequently, which will shorten its life. One that is set too high will not allow the generator to charge at lower engine speeds. A good original-type cutout or quality repro is a very durable device if adjusted properly and not abused.
Who adjusts their cutouts? Most of the cans on the original ones are spot welded shut.


Been Here Before
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Re: Generator Cutoff relay

Post by Been Here Before » Tue Jan 31, 2023 11:40 am

There are may vehicles that use a cut out on the generator to control current flow.

"The Cutout
In its simplicity a cutout is a magnetically controlled switch that provides a path for current flow from the generator to the battery. The cutout permits charging of the battery when the engine is running and prevents the battery from discharging when not. "

For example on the Model T, a tractor cut for 6 volts will work. Check with an early farm tractor part supplier. Or even a period car Dodge, Chevy, Maxwell etc.

As for how a cut is made an works see : http://modelabasics.com/Cutout.htm

Google - generator cut out.


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Re: Generator Cutoff relay

Post by Art M » Tue Jan 31, 2023 11:45 am

I used to use 4 D cell batteries in series to set the cutout. This seemed to work well. The closing voltage must be higher that the car battery voltage.
I now use a DC power supply with virtually no ripple to set the closing voltage.

Art Mirtes.

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Mark Gregush
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Re: Generator Cutoff relay

Post by Mark Gregush » Tue Jan 31, 2023 5:06 pm

I have not tried to adjust one but have a WWII war surplus generator diagnostic tool with instruction manual and am pretty sure that shows how to do it.
I know the voices aren't real but damn they have some good ideas! :shock:

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Re: Generator Cutoff relay

Post by tdump » Wed Feb 01, 2023 9:30 pm

Is it possible to just buy a diode on ebay of a certain part number and install it in a old housing?
I am thinking the bar with arrow would point towards the generator so power could leave the gen but not go back in from the battery ,correct?
If you can't help em, don't hinder em'


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Re: Generator Cutoff relay

Post by Luke » Thu Feb 02, 2023 2:18 pm

tdump wrote:
Wed Feb 01, 2023 9:30 pm
Is it possible to just buy a diode on ebay of a certain part number and install it in a old housing?
I am thinking the bar with arrow would point towards the generator so power could leave the gen but not go back in from the battery ,correct?
Mack,

Yes, you can do that. The diode will need to be rated to the expected current supply and a bit more. I suggest a 100V 20A or better silicon power/switching diode, should allow a good margin. FWIW a schottky diode may be preferable as it should run cooler, but isn't imperative.

I see on ebay.com you can get 10 x 30A 100V schottky diodes for circa $5-$10, this'd give you a few spares!

In terms of how to connect it up I think this site should explain diode polarity ok? : https://www.wikihow.com/Tell-Which-Way- ... -Should-Be

If you do this you'll need to reset the generator current with the third brush, given the forward resistance of the diode will be different than an old school mechanical cutout. Keep it as low as you need, LED lamps will ensure that a mere 4A or less should suffice.

Luke.

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TRDxB2
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Re: Generator Cutoff relay

Post by TRDxB2 » Thu Feb 02, 2023 3:46 pm

Modifying an existing cut-out is a relatively simple task - just buy one from Lang's or eBay (32-748 Diode, 25 Amp 200 Volt 1/2 Press-Fit)
Not all cut-outs have the same insides as pictured (2 different pictured)- but their bracket is insulated to the base

1. Carefully remove the cover. usually one or two small take welds
2. Remove the solenoid parts and like the bracket
3. drill out a hole for the diode. The bracket acts as a heat sink
4. solder to previous point used by solenoid to battery
5. Replace cover and secure with silicone seal
6. Bench Test - continuity from generator connection (+) to battery connection (-). No continuity with leads reversed or either connection to base or cover.
Diode  update.jpg
The past is a great place and I don't want to erase it or to regret it, but I don't want to be its prisoner either.
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tdump
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Re: Generator Cutoff relay

Post by tdump » Thu Feb 02, 2023 9:21 pm

Well it so happens I pulled the canvas off the speedster project and started scroungeing up parts stuffed in nooks and cranys in the shop and i had bought 1 of those diodes! and had a cut out in the bag with it and was apparently looking at doing this during the last work on the project.
That is I guess 1 of the "good" things about closed head injury related memory issues, you get surprises! Gee did I order that? Wow!
If you can't help em, don't hinder em'

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