⚡ Non-Ballast Ignition Coil:

• No Ballast Resistor Used.
• Voltage at Coil: Designed to run at full 12 volts continuously.
• No Start Bypass Needed: It’s built to handle the full voltage without damage.
• Common In: Most classic cars up to the 1970s.

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🔧 Ballast Ignition Coil:

• Used with a Ballast Resistor (or a resistance wire).
• Voltage at Coil: Normally runs at 6 to 9 volts during engine operation.
• Starting Boost: During startup, the ballast resistor is bypassed so the coil gets a full 12 volts to help with cold starts.
• Purpose of Ballast Resistor: Limits current after starting to protect the coil and prolong its life.
• Common In: Fords from 1968, many Triumph models, and widely used from the early 1980s.

⚠️ If you remove the ballast resistor and run 12V full-time to a ballast coil, it will overheat and eventually fail.

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🔍 How to Tell the Difference:

• Resistance Check (Primary winding):
  • Ballast Coil: ~1.5 ohms or higher
  • Non-Ballast Coil: ~3 ohms (higher resistance)
• Labeling: Some coils are marked “Use with Ballast Resistor” or “12V” (non-ballast).