what size diode do I need

[rockfla]

Building a jumper wire for a 6V coil, is there a particular amp rating or mili-volt rating for the in-line diode i need? OR is the diode really necessary?

[ford38v8]

Not sure about the size rating, but the diode is certainly necessary unless the jumper is on a normally open toggle switch.

[Jack E/NJ]

An in-line diode to hot wire a coil?

[rockfla]

Originally Posted by Jack E/NJ

An in-line diode to hot wire a coil?

Just for you!!!

[Zeke3]

The diode should be sized for the current and voltage it is going to be exposed to. What is the resistance of the primary circuit of the coil you will be using and the battery voltage? You can calculate the current using Ohm's Law, E=IR. That should get you in the ball park, unless I screwed something up.

[rockfla]

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6V system and the coil is for a 9N Tractor SO not sure what the data is for that???

[Kube]

Originally Posted by rockfla

Building a jumper wire for a 6V coil, is there a particular amp rating or mili-volt rating for the in-line diode i need? OR is the diode really necessary?

Properly installed, you will have a full 6v to the coil while cranking the starter. Stop cranking and the voltage will drop back to where it needs to be.

[koates]

The diode you require should be able to handle about 8 amps. Voltage specs dont matter. An old alternator main (top hat) type of diode would work ok. Make sure you fit it the correct way around otherwise it wont pass any current to the coil. Dont allow it to touch any metal of the car body. Regards, Kevin.

[rockfla]

Originally Posted by koates

The diode you require should be able to handle about 8 amps. Voltage specs dont matter. An old alternator main (top hat) type of diode would work ok. Make sure you fit it the correct way around otherwise it wont pass any current to the coil. Dont allow it to touch any metal of the car body. Regards, Kevin.

Thank all for your guidance!!

[supereal]

Thanks for posting my original "quick start" page. The purpose of the circuit is to compensate for draw down on the battery from the starter motor during cranking.
Any "top hat" diode will work, as it just augments the coil voltage until the engine starts,
using low current. Be sure to install the diode as shown to prevent energizing the coil after starting. Polarity is important. If "backward" the engine will start without turning on the ignition. Just reverse the connections to the diode.

[solidaxle]

Rockfla
Can you draw in the rest of the diagram showing the battery and push button.

[petehoovie]

Originally Posted by solidaxle

Rockfla
Can you draw in the rest of the diagram showing the battery and push button.

[34PKUP]

[QUOTE=petehoovie;2106564]

Really? Could be wrong but just wondering how long it will run hooked up like this?

[ford38v8]

[QUOTE=34PKUP;2106619]

Originally Posted by petehoovie

Really? Could be wrong but just wondering how long it will run hooked up like this?

I see what your confusion is. This diagram is not complete, as it is intended only to show the bypass circuit, and not the normal ignition circuit. The circuit you see here is only active during the time the starter is energized.

[ford38v8]

[QUOTE=34PKUP;2106619]

Originally Posted by petehoovie

Really? Could be wrong but just wondering how long it will run hooked up like this?

I see what your confusion is. That diagram is not complete, as it is intended only to show the bypass circuit, not the normal ignition circuit. The circuit you see here is only active during the time the starter is energized.

[Mart]

Would it be simpler to use a relay to achieve the same goal?
Is this a band aid to try and overcome a problem elsewhere?
Millions of Fords started without a hot wire jump, why would we need one now?
Not knocking it, just curious as to why one would be required.
Mart.

[69a]

Originally Posted by Mart

Would it be simpler to use a relay to achieve the same goal?
Is this a band aid to try and overcome a problem elsewhere?
Millions of Fords started without a hot wire jump, why would we need one now?
Not knocking it, just curious as to why one would be required.
Mart.

All your MKIII Cortinas used a 6V coil wired through a resistor, and a hot wire from the starter solenoid. So you got 12 to the coil while you were cranking the starter and 6V for the rest of the time. The hot wire with a diode is a brilliant idea.

[petehoovie]

Originally Posted by 69a

All your MKIII Cortinas used a 6V coil wired through a resistor, and a hot wire from the starter solenoid. So you got 12 to the coil while you were cranking the starter and 6V for the rest of the time. The hot wire with a diode is a brilliant idea.

This "hot wire" ckt. is especially useful when you have a weak battery...

[rockfla]

Originally Posted by petehoovie

This "hot wire" ckt. is especially useful when you have a weak battery...

Petehoovie


My Optima is up to 6.4V. It seems to "initially" spin the motor a little better SO my plan IS to use it in conjunction with my wet cell via jumper cables for starting.....I've pulled my battery out of the Mercury for my "jumper" power source AND IF need be I have a 12V battery I can swap my jumper cables to and go directly to the starter with that to get it spinning!!! Thoughts???

[bobH]

Strictly opinion... and we all know what that's worth... Sure, it's a 'band-aid'. But, jillions of cars/pickups are using this 'band-aid'. Factory installed, the full battery voltage is picked up off of a terminal on the starter switch (starter solenoid). Ford and Chevy started doing this, 55 for Chevy, 56 for Ford. That's why you see those two small terminals on the starter switch, labelled 'I' (for ignition), and 's' (for start). 'I' gets battery voltage when you hit 'start'.

(For Mart... Do I recall that you have a 'Bird'? 56 or newer? If so, I believe you will find the 'I' terminal on your starter switch....)