Posted by John T on May 04, 2010 at 06:45:04 from (66.244.97.31):
In Reply to: coils posted by bspauld on May 04, 2010 at 05:54:27:
NOTE, theres a bit of "semantics" going on with this whole coil voltage thing, myself and Bob and JD have discused this ad nauseaum lol heres the real deal from a long retired electrical engineers perspective:
1) They design amd manufacture Kettering Ignition System Coils designed to operate at 6 volts nominal across the primary which can handle the current, dissipate the heat, and still provide the sufficient voltage and energy for a suitable spark when the voltage is reduced while cranking, yet raised (maybe to 7 volts) at fast RPM when the battery is charging.
I CALL THEM 6 VOLT COILS AND STAND BY THAT
2) They design amd manufacture Kettering Ignition System Coils designed to operate at 12 volts nominal across the primary which can handle the current, dissipate the heat, and still provide the sufficient voltage and energy for a suitable spark when the voltage is reduced while cranking yet raised (maybe to 14 volts) at fast RPM when the battery is charging.
I CALL THEM 12 VOLT COILS AND STAND BY THAT and have, like others, referred to them as true 12 volt coils as they are for 12 volts nominal across their primary NOT 6 NOT 8 but 12, and they will still handle the current, dissipate the heat and provide sufficient voltage and energy for a spark even at reduced cranking voltages or increased charging voltages. They are labeled 12 volt. I guess one could call them a 9 to 15 volt coil??????? as they can provide a spark while cranking or charging, but I prefer to call them a 12 volt coil or a true 12 volt coil NOT a 9 to 15 lol THATS A SEMANTICS ISSUE
BUTTTTTTTTTTTTTTTT NOW GET THIS WHICH CONCERNS LABELLING ON THE COIL AND WHERE THE RUB COMES IN
A) Some coils are labeled "12 volts" OR "12 volts NOT for use with Ballast Resistor"
I CALL AND CONSIDER THEM AS 12 VOLT COILS and some folks (semantics issue) refer to them as "Internally Ballasted" BUTTTTTTTTTTTTTTTTT they are still designed to operate and handle the current and dissipate the heat and provide a spark (at reduced cranking voltage or increased charging voltage) at 12 volts nominal across the primary. THEY ARE INDEED 12 NOTTTTTTTT 6 VOLT COILS
B) HOWEVER AND NOTE THIS CAUSES MORE CONFUSION TO SOME, some coils are labeled "12 volts to be used with external ballast resistor" or "12 volts requires external ballast" etc
SOOOOOOOOOOO these mean EXACTLY what they say, if you want to use them on a 12 volt tractor YOU MUST USE THE EXTERNAL SERIES VOLTAGE DROPPING (12 to 6) BALLAST RESISTOR otherwise they can overheat and be ruined. They are in one view in reality 6 volt coils since they are designed to operate WITH ONLY 6 VOLTS ACROSS THEIR PRIMARY as the 12 battery volts is reduced down to 6 by a 6 volt drop acros the external ballast. They can be used on a 12 volt tractor but "require an external voltage dropping (12 to 6) ballast JUST LIKE THEY SAY.
SOOOOOOOOO they can make a common (what I'd consider (semantics) as a 6 volt) coil that can be used on EITHER a 6 or a 12 volt tractor understand???????? Its just that if used on a 12 volt tractor they require the external series voltage dropping (12 to 6) ballast resistor buttttttttttttt if used on a 6 volt tractor NO BALLAST IS USED.
ALMOST FINALLY: If you go to a parts store and ask for an ignition coil for your old tractor IM CONFIDENT THEY WILL ASK IF YOU WANT A 6 OR 12 VOLT COIL AND THEY WILLLLLLLLLL NOTTTTTTTTTT SAY THEY ARE ALL THE SAME. NOTE However as above, you can use a 6 volt coil on EITHER a 6 or 12 volt tractor provided if on a 12 you add the series voltage dropping (12 to 6) ballast resistor in which case the coil only sees 6 volts which is why I still consider it a 6 NOT a 12 volt coil.
FINALLY: Could they design and manufacture a coil that can actually be used on EITHER a 6 or 12 volt tractor, AS AN ENGINEER IM SURE THEY COULD and would expect its primary resistance to be well over 2 ohms and its design parameters would be that if EITHER 6 or 12 volts were applied (NO BALLST MIND YOU) they can still handle the current, dissipate the heat and provide sufficient voltage and spark energy if used on a 6 volt or a 12 volt tractor unballasted. HOWEVER the more normal typical situation is EITHER 6 or 12 volt coils NOTTTTTT a one size fits all common generic coil.
HEAT DISSIPATION AND SPARK ENERGY:
a) If you use a 6 volt coil on a 12 volt tractor and dont use a series voltage dropping (12 to 6) ballast resistior THEY CAN OVERHEAT BADLY AND BE RUINED
b) If you use a 12 volt coil on a 6 volt tractor, they sure dont overheat buttttttttttt the spark energy will be very weak
THATS WHY THEY DESIGN AND MANUFACTURE 6 AND 12 VOLT COILS WELLLLLLL DUHHHHHHHHHHHHHHH yet you can still use a 6 volt coil on a 12 volt tractor with the series voltage dropping (12 to 6) ballast
THATS MY STORY AND IMA STICKIN TO IT UNTIL PROVEN OTHERWISE LOL
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