What is it and how does it on a 6 volt Chief

[Phathog]

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I was wondering if anyone had ever seen a homemade setup like this before? The symbol on the round item with the wire soldered in the middle indicates that it is a diode. There are different types of diodes but the symbol seems to indicate that this is a simple one-way current flowing diode. Yet, I could be wrong about it because while I know that diodes will only allow current to flow in one direction; I don't understand how this one could break the current flow when the battery is fully charged.
The gadget came off my 1948 Indian Chief that I purchased about 6 months ago. I rode the bike fairly regular until the generator stopped charging and battery died on a ride a couple of weeks ago. I pulled the cover off to check the cutout relay, and this contraption is what I found.
I am very familiar with the cutout relays used on Harley 32Es and John Deere Delco Remy generators but I have never seen one of these before. I found a broken wire in the generator and the fields look like they may need to be rewrapped. Just not sure what to do with this thing. Should I get a replacement cutout relay or should I try using this thing when I finish rebuilding my generator?
Thanks, Joe

[Jerry Wieland]

It is a diode and diodes prevent electric current from back flowing. It would work real similar to a cutout relay like a Chief had originally. Jerry

[Rubone]

It works purely off of a pre-set voltage level (built into the diode itself). When it drops below the level of the diode it closes and allows current flow, when the voltage equalizes it opens. Just an on/off switch.

[Phathog]

Very Interesting! it makes sense that something similar to a Schottky Diode could replace a cutout relay. Do y'all have any experience with these? Does it make a good replacement for the cutout relay.

[1950Panhead]

I was wondering if anyone had ever seen a homemade setup like this before?

This is a fred flintstone cutout relay.
I would use it, watch battery water level, if water drops you need a regulator.

[bstevens479]

The Autolite relay is open no current flowing or closed battery being charged the diode does the same job current only flows in one direction make sure diode is rated high enough for max current, it will work fine

[Phathog]

I am impressed by whoever built this thing. It is crude looking, yet well thought out. Someone apparently discovered the right voltage-drop diode. Think I'm going to play around with it while I am waiting on the field windings for my generator and see if I can determine the working voltage range. Has anyone else seen this done before? I was also wondering if it would be possible to build a cutout relay for a 32E using a Schottky Diode?

[Paultrehberg]

Looks like a 100 amp diode commonly used in electroplating . I have installed many in industrial e-coat systems. They are not used to limit voltage or current. They will pass current up to their designed limit. They will not cut out voltage or current , only burn out if current is exceeded .

[Phathog]

In other words, it does not function in a manner that will allow it to replace an actual cutout relay. I'll admit that I had my doubts since I had never seen anything like it before on a charging system, and with new relays costing close to a buck and a half, surely someone would be marketing them. I picked up a rheostat the other day and I had planned to play with it to see if the diode really worked. Maybe I can use the rheostat to check out the relay I snagged on EBay the other day. I'll be out of pocket for a few days but I report my findings with the diode and the cutout relay soon as I get a chance.

[tfburke3]

In other words, it does not function in a manner that will allow it to replace an actual cutout relay. I'll admit that I had my doubts since I had never seen anything like it before on a charging system, and with new relays costing close to a buck and a half, surely someone would be marketing them. I picked up a rheostat the other day and I had planned to play with it to see if the diode really worked. Maybe I can use the rheostat to check out the relay I snagged on EBay the other day. I'll be out of pocket for a few days but I report my findings with the diode and the cutout relay soon as I get a chance.

I think it will work like a cutout.
Hook the battery up to the battery side and a light bulb to the generator side.It should not light.
Connect battery to gen side and light bulb to battery side and it should light.
Tom

[BoschZEV]

the symbol seems to indicate that this is a simple one-way current flowing diode.

Assuming whoever made that knew enough to use a Zener diode, and assuming the contacts hidden from view are correct to connect the positive terminal from the generator to the wire soldered to the diode, when the engine is running current will flow from left to right through the diode (the "arrow" on the diode points in the direction of current flow). Zener diodes come in a wide range of Zener voltages and power handling capability. When the engine stops the battery will "want" to discharge back through the generator. However, if the diode has a Zener voltage of greater than ~8 Volts (for a 6 V battery) the current flow in the reverse direction through the diode will be less than 1 mA.

For a, say, 10 A-hr battery the tiny ~1 mA (or less) reverse current flow through the diode that means it will slowly discharge in a time approx. 10 A-hr/1mA = 10,000 hrs =~1 year. It is because of this that a Zener can be used as a cutout. However, all of this assumes that the guy who crudely fashioned that device used a component with the necessary electrical specifications, made the correct connections, didn't damage the diode with his crude soldering, and the heat sink is adequate to deal with the power dissipated in the diode.

[Phathog]

Thanks everyone. I did a little reading on the subject of Zener diodes, and I tell you, that is pretty intreging stuff. I have fallen off the electronic bandwagon the past few years and I see that I have some catching up to do. It will most likely be one day next week before I have time but I plan to sit down with a 6 volt battery, a rheostat, and a multimeter and play with this thing. I'll report back with my findings soon as have them. Surely, it is possible to build a dependable cutout relay replacement using modern components. In the meantime, I have some technological reading to do.

[Robert Luland]

I agree with phathog. I think it great the way he was able to make the mounting bracket the heat sink and make it all fit. That's a big diode and I doubt it is sized to go off and on. I think it just serves as a check valve and nothing more. Bottom line is if the system is balanced with a nice large OEM type battery. Why wouldn't it work just fine. If ya find the water getting a little low just lay off some action by switching on the CB and sub woofer amp. Bob L

[BoschZEV]

I think it great the way he was able to make the mounting bracket the heat sink and make it all fit.

That block of Al is only a heat sink insofar as there is a source of cooling (e.g. if hanging in the breeze). If making it fit means there's a cover that goes over it the cooling will be severely limited and the temperature will rise to the same point as it would had the Al been much smaller. Diodes have "small" resistances in the forward direction so the I²R heat generated by the current flow through them is relatively small but that heat still has to have a way to get out or the temperature will rise, possibly to the point of failure.

[Phathog]

It also runs a TV and a microwave as well. You gotta have popcorn with the movie.