# Question: What Size Ballast Resistor Do I Need For 49 8n Tractor 12v?

## Does a 12 volt coil need a ballast resistor?

If a 6 volt ignition system is converted to 12 volts and a Delco style 12 volt coil with an internal resistor is installed as part of the conversion, no external resistors are required. The 12 volt battery must be connected so the negative (-) battery terminal is connected to ground.

## How many ohms should a 12 volt coil have?

The normal, acceptable range for a standard 12 – volt car is 1.5 to 1.7 Ohms.

## Why does a 12V coil need a resistor?

When a 6 volt ignition system is converted to 12 volts either a 12 volt coil must be installed or a resistor installed in the circuit to reduce the coil voltage to 6 volts. The resistor regulates the voltage, keeping it at 6 volts, allowing the original 6 volt coil to be used in a 12 electrical system.

## Do I need a ballast resistor with MSD ignition?

You do not need the ballast resistor. You need a hot 12v (always hot) & a switched 12V(key on), this wire must be hot when cranking. Location: Manheim Pa. MSD says there systems will give full coil voltage with 9-18 supply voltage, operate with as low as 5 volts & take a momentary voltage as high as 24 volts.

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## When would you use a ballast resistor?

A ballast resistor is used in a circuit to limit the current and hence prevent it from over current faults. Here, as the current in the circuit varies and increases above a particular threshold value, the resistance also starts to increase.

## How many volts should a coil have?

The voltage reaching the coil may be 12 volts, or about 7 volts if the coil has a ballast resistor. Most electrical equipment works on 12 volts, but most modern cars have a resistor in the ignition system to assist starting. The coil in a ballast-resistor system is rated at 7-8 volts instead of 12 volts.

## Should negative side of coil have power?

The power from the ignition switch need to go to the plus side of the coil and the negative goes the the distributor on a 12v system. That should be opposite what it was on a 6v positive ground.

## How many ohms Should a coil pack read?

Most coils should read between 0.4 and 2 ohms. Zero resistance would indicate a shorted coil while a high resistance reading would indicate an open coil. Secondary resistance is measured between the positive (+) terminal and high voltage output terminal.

## Is there a difference between a 6 volt coil and a 12 volt coil?

If you have an accurate ohm meter, reading across the posts of a 12 volt coil should be about 3 ohms. A 6 volt coil is about half of that. It is not an exact number, but close enough that you can tell 6 from 12 volt. Or, doing what Tom says, a 12 volt coil will flow about 2 amps if connected to 6 volts.

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## What is an external resistor on an ignition coil?

The external resistor coils were used to boost primary ignition voltage during starting (making starting faster/easier). During starting, the external resistor is bypassed; once the starter is disengaged, power to the coil flows through the external resistor.

## How do you measure the resistance of a coil?

Turn your multimeter dial to the lowest ohms setting, usually 20 or 200. Place the two probes on the atomizer your coil is in, one probe on the positive pin (the one in the middle of the 510 connection), and the other on the outside 510 threading, to get the total resistance of the coil in the atomizer.

## Does a ballast resistor need to be grounded?

A Ballast resistor should NEVER be grounded! One side of it will go to the 12 volts on The Ignition switch, The other side should go to the + side of the coil

## What happens when a ballast resistor goes bad?

If your ballast resistor is bad, your vehicle will not run and you will have to have it towed to the mechanic’s shop. The biggest sign your ballast resistor is bad is your vehicle will start, but immediately stop as soon as you let go of the key.

## What does a ballast resistor do in an ignition system?

The duty of the ballast resistor is to limit voltage to the ignition coil. This added longevity to the coil as well as protected the ignition system from over-voltage. Symptoms of a bad ballast resistor may be a crank but no start or start followed by an immediate stall.