720 LP Coil

[DeereJohn1]

My new to me 720 LP has one set of battery cable under the seat - I assume it used just 1 12 volt battery? Can anyone tell me the correct coil part number from Napa, O'Reilly's etc?



Thanks

 

[used red MN]

Hello DeereJohn1, welcome to YT! From another member @Jim.ME posted for the same question for a 3020 but should be the same since both are 12 volts.
“Standard Motor Products UC 15 and NAPA IC 14 are both shown as 12-volt coils that require no external resistor.”
I am nearly certain his information is correct.

 

[DeereJohn1]

Hello DeereJohn1, welcome to YT! From another member @Jim.ME posted for the same question for a 3020 but should be the same since both are 12 volts.
“Standard Motor Products UC 15 and NAPA IC 14 are both shown as 12-volt coils that require no external resistor.”
I am nearly certain his information is correct.

Thank you!

 

[TheBartman47]

If your 720 LP is like my 730 LP, it originally came with two 6v batteries in series, but a single 12v battery works just fine. As for the coil, the original has an external resistor setup. The resistor is mounted on the front cover plate where the main switch, start button, and tachometer are. 4 bolts hold it on, loosen them and pull the plate back to see if there is a resistor in there. If the resistor is connected, then you want a coil that is no internal resistor. If the resistor is bypassed, then you'll want a coil with internal resistor.

 

[buickanddeere]

Hello DeereJohn1, welcome to YT! From another member @Jim.ME posted for the same question for a 3020 but should be the same since both are 12 volts.
“Standard Motor Products UC 15 and NAPA IC 14 are both shown as 12-volt coils that require no external resistor.”
I am nearly certain his information is correct.

wrong, the LP spark ignition 12V tractor use bypass starting .

 

[used red MN]

wrong, the LP spark ignition 12V tractor use bypass starting .

Okay, sorry for the misinformation. I suspect if you had the NAPA part number he wanted you would have posted it.

 

[Jim.ME]

Standard UC 14 or ECHLIN IC 7 are 6-volt coils, cross from some JD part numbers, and should work with the starting bypass.

 

[DeereJohn1]

Standard UC 14 or ECHLIN IC 7 are 6-volt coils, cross from some JD part numbers, and should work with the starting bypass.

Should I use a 12 volt since that’s the battery voltage?

 

[Jim.ME]

Should I use a 12 volt since that’s the battery voltage?

Not if the original resistor is still in the ignition system wiring. The resistor allows the 6-volt coil to work on 12 volts. The resistor also allows for the resistor bypass circuit to work when starting. That circuit provides full battery voltage to the ignition during starting. If you still have the original resistor (located as TheBartman47 posted) in the circuit, you need to use a 6-volt coil.

You need to determine if the resistor is still in the circuit.

 

[DeereJohn1]

Not if the original resistor is still in the ignition system wiring. The resistor allows the 6-volt coil to work on 12 volts. The resistor also allows for the resistor bypass circuit to work when starting. That circuit provides full battery voltage to the ignition during starting. If you still have the original resistor (located as TheBartman47 posted) in the circuit, you need to use a 6-volt coil.

You need to determine if the resistor is still in the circuit.

Good to know. Thank you!

 

[DeereJohn1]

Not if the original resistor is still in the ignition system wiring. The resistor allows the 6-volt coil to work on 12 volts. The resistor also allows for the resistor bypass circuit to work when starting. That circuit provides full battery voltage to the ignition during starting. If you still have the original resistor (located as TheBartman47 posted) in the circuit, you need to use a 6-volt coil.

You need to determine if the resistor is still in the circuit.

I zoomed in on some photos I took - is this the resistor? If so, does this verify a 6 volt coil with external resistor?

 

[Jim.ME]

Good to know. Thank you!

I zoomed in on some photos I took - is this the resistor? If so, does this verify a 6 volt coil with external resistor?

That appears to be the resistor in question. A 6-volt coil would be used with it.

Do you have Service and Operator's manuals for your tractor?

 

[DeereJohn1]

That appears to be the resistor in question. A 6-volt coil would be used with it.

Do you have Service and Operator's manuals for your tractor?

I do not, but plan to order - ok to use a 6 volt coil that says "No external resistor needed" or does it require one that says "External resistor required"

 

[buickanddeere]

Should I use a 12 volt since that’s the battery voltage?

Did we not mention by-pass starting ?

 

[buickanddeere]

I do not, but plan to order - ok to use a 6 volt coil that says "No external resistor needed" or does it require one that says "External resistor required"

Need a coil that measures roughly 1.5ohms across the primary windings .

 

[Jim.ME]

I do not, but plan to order - ok to use a 6 volt coil that says "No external resistor needed" or does it require one that says "External resistor required"

I don't know why they started adding that wording on the 6-volt coils. When that coil is used on a 6-volt system it does not need an external resistor to be used with it. If you use it on a 12-volt system, it needs an external resistor.

Maybe you will be more comfortable with one of these.