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B_man_Al · 07-31-2013, 11:43 AM

Hi George ...

My 8BA is not on the road yet, so its only running in the garage occasionally. This is the one I did the measurements on. However I converted my 4 cyl Model B to 12v the same way in 2007 with no problems. Its been 5 yrs now and about 6000 mi. Almost all the miles are racked up on tours with the model A club, so the runs are usually all day long during the summer and fall.

The ballast resistor comes from MACS, part number A12001 and is recommended for converting 6V coils for 12v operation. I'll go make some measurements in the next day or so.

I'm curious why you think the current should be around 2A. A 1.5 ohm coil and a 1.5 ohm ballast will be around 4A peak when cold and drop to about 2-3A when hot due to the increase in resistance of the coil and ballast with temperature.

If however you take the AVERAGE current it will likely be in the 2A range because the points are open for part of the cycle, and therefore current is not flowing .

07-31-2013, 11:43 AM	#48
B_man_Al Senior Member Join Date: Feb 2011 Location: Ottawa ON Canada Posts: 301	Re: Mallory tech answer to coil/ballast ? Hi George ... My 8BA is not on the road yet, so its only running in the garage occasionally. This is the one I did the measurements on. However I converted my 4 cyl Model B to 12v the same way in 2007 with no problems. Its been 5 yrs now and about 6000 mi. Almost all the miles are racked up on tours with the model A club, so the runs are usually all day long during the summer and fall. The ballast resistor comes from MACS, part number A12001 and is recommended for converting 6V coils for 12v operation. I'll go make some measurements in the next day or so. I'm curious why you think the current should be around 2A. A 1.5 ohm coil and a 1.5 ohm ballast will be around 4A peak when cold and drop to about 2-3A when hot due to the increase in resistance of the coil and ballast with temperature. If however you take the AVERAGE current it will likely be in the 2A range because the points are open for part of the cycle, and therefore current is not flowing .