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Subject: 48 8n front 12v coil amperage

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tim sullivan    Posted 08-22-2017 at 10:40:41 [URL] [DELETE]        [Reply] [Email]  
  • 48 8n front 12v coil amperage
  • I would first like to say I am sorry to anyone offended for my converting to 12 volt, was not my call, but I must deal with it. The kit and harness install went very well, problems surfaced with the proper resistance for the new 12v coil, which measures 2.7 ohm + the stock ballist resister at 1 ohm warm gives me 3.9 amps to the coil when running. A ceramic resistor was provided with the kit, which at 5.0 ohms, is unusable even with the original 6V 1.5 ohm coil, as I would be down to 2.23 amps running. So I see a ceramic resistor for sale at 0.6 ohms I could add that would have the coil running warm at 3.37 amps. Leave it alone at 3.9 amps? add the .6 ohm resistor? I have read that about 3.5 amps is the target, is that correct? Thank you for the help.

    36 coupe    Posted 08-22-2017 at 16:54:14 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 48 8n front 12v coil amperage
  • You will have to get the starter rewound for 12 v to stop drive breakage.Ford did make the Transit Bus in 1938 with a 12 volt system.Ford does make a big van now with the transit Name on.Sorry if I know more about Ford electric systems than you.

    deanostoybox    Posted 08-22-2017 at 17:56:44 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 48 8n front 12v coil amperage
  • I would be leery of the 0.6 Ohm resistor right now.

    may explain the odd resistance of the one you got in the kit.

    36 coupe    Posted 08-23-2017 at 18:55:11 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 48 8n front 12v coil amperage
  • Most ohmmeters are not accurate at this low range...

    JMOR    Posted 08-24-2017 at 00:08:49 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 48 8n front 12v coil amperage
  • Resistance can be measured much more accurately by means other than an Ohmmeter if one knows how.

    Tim Pelee Is. ONT    Posted 08-24-2017 at 08:53:22 [URL] [DELETE]        [Reply] [Email]  
  • Re: 48 8n front 12v coil amperage
  • JMOR, using a calibrated Fluke DVM (work perk) , using assumed 14.5Volt divided by resistance to get Amps. Are you one who knows? I just want to make sure coil/points live long on an old tractor. An education along the way, when provided, adds to the fun.

    JMOR    Posted 08-24-2017 at 10:33:52 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 48 8n front 12v coil amperage
  • Tim, that sounds good. The difficulty in measuring low resistances is not only a GOOD CALIBRATED METER, BUT METHOD. Play with meter a bit & you will find that how hard you press the leads to the terminals of device being measured will alter those low resistance readings. The current being forced thru the device is passing through the same connections & leads as the measuring circuit. You can emulate precision 4 lead meter by using a calibrated source to apply a known fixed current (say 1/2 to 1 ampere) to the device and then with your voltmeter measure the device voltage & calculate the resistance. This is about as good as you can get outside the laboratory & even this depends on very careful attention to test lead placement & simultaneous use of two meters (ammeter & voltmeter).

    Bruce (VA)    Posted 08-22-2017 at 11:44:20 [URL] [DELETE]        [Reply] [Email]  
  • Re: 48 8n front 12v coil amperage
  • Leave it alone. 3.9 amps is close enough. Just don't ever leave the key on

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