6 or 12 volt coil ?

Anonymous-0 · Sep 26, 2009

How can you tell the diff. from a 12 volt or a six volt coil thats not marked? what test do you do?

JMOR · Sep 26, 2009

(quoted from post at 10:17:56 09/26/09) How can you tell the diff. from a 12 volt or a six volt coil thats not marked? what test do you do?

You can use just about any coil on a 12volt system IF you use the correct ballast resistor with it to establish proper current (about 4 amps stalled).
The 'true' 12volt coils , such as NAPA IC14SB (3.25 ohms), which require no ballast resistor can be identified by measuring their primary resistance with an ohm meter. They will measure between 3 & 4 ohms, where as the 6v coils will measure about one-half of that & in some cases even less.

John T · Sep 26, 2009

Most typical 6 volt coils will have a primary resistance as measured between its little + and - terminals in the range of 1.5 ohms (1.25 to under 2),,,Most typical 12 volt coils have around 3 ohms (2.5 to under 4)......The reasons for those values is to limit the amount of current the points have to switch on and off in the 4 amps range otherwise they can burn up prematurely plus a weak or no condensor likewise makes them burn up prematurely.

Is there a ballast resistor on the tractor?? If it was 6 volt with 6 volt coil there wouldnt be one.......If a 6 volt tractor like an H got converted to 12 volts, it needed EITHER an external ballast with the old 6 volt coil or else a new full true 12 volt (some call internally ballasted) coil......

John T

6 or 12 volt coil ?

Anonymous-0

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JMOR

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John T

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