My new 26 T Roadster came with a 12v battery, positive ground. I changed it back to negative ground and went through the wiring, things did not match the T schematic. It runs real good on the 12v battery and bad on the mag, only 8v max. I had no output on the generator so I polarized it and it now produces. The output is 14.2v and 18 amps at road RPM. I like the volts but not the amps. At idle I get 13.6v and 1.6 amps with a digital clamp on. I have read that a T gen. will support a 12v system but I need to get the amps down. The cutout opens when shut down. I'm working with a new battery with the charge topped off. Any suggestion or information on this type of set up is welcome. Thanks PK.
Well so far so good but you are correct you are running the generator way way too high and it won't last long that way. You might be able to strengthen the magneto later but for now you need to lower the 3rd brush setting on the generator. The T generator is capable of about 100 Watts. That's a total of 7 amps absolute maximum at 13.6 volts. Since you are using a digital clamp on at the idle reading might I assume you are also using the digital clamp on at "road RPM"?? The reason I ask is that digital readings are notoriously inaccurate around a T with its operating coils generating lots of radio frequency noise. It has nothing to do with the quality of the digital meter but everything to do with the RFI that is getting into the meter. Does the car have an ammeter in the dash that is working? If you didn't reverse the wires to it then it will be reading backwards since you reversed the battery to have it now correct at negative ground. You will need to swap the ammeter wires to get "discharge" readings when you operate the lights with engine not running. Why not verify those things back to me before we go any further. Please refrain from running the motor until the generator setting is resolved since you can do serious damage to the generator if you are indeed running it at 18 Amps and 14.2 Volts since that is 255 watts which is 2.5 times its maximum rating of 100 watts. I kinda question your readings and wonder what meter gave those readings. The adjustment of the 3rd brush is rather easy but you need to know you have a way of measuring what you are doing.
John, I sent pat this message and I completely agree with you , I figured someone would help him with the magneto situation,
Mr. Kelly, with your battery fully charged and you still are having an output of that much amps, YES that will be a problem for you on extended drives, I believe you have the original 3 brush generator still, unless changed , those generators require you to adjust the 3rd(adjustable brush) to raise or lower the output, usually during day time operation , you have the brush adjusted to put out less, then at night with the lights you adjust it up, its just necessary for that type of generator, if that's what you have still have, I would ask about the lights, if original or halogen or any newer lights, because they will require more amps, that is the reason so many use the alternator, its regulator controls the output according to your load demand, and if you use the higher amp needed lights and/or any accessories , or say your going on extended drives, you have no need to get out and adjust the brush, the alternator will go from zero need to as much as your vehicle asks for, people only add a alternator for those reasons, along with actually more reliability also, But as for original , they use there generator, alternators are common now it seems because people use there car for drivability, its actually only a personal preference, I don't mean to push you into a alternator at all , just giving you the information and options. hope you solve your problem easily, Happy motoring Daryl
I for one would have to say , that sticking with your original generator, John definitely sounds like the person to have helping you !!!! just an observation
Why don't you help him with the magneto situation?
I am familiar with a magneto but definitely not an expert , I knew you or a few others here would jump in on that subject, I would never want to mislead or give any information out if I wasn't 100% on it, as my father used to say when asked why he didn't work on AC motors, I do DC that AC stuff will kill ya !! Ha Ha
The car has the original type generator, no Ford logo on the cut out. The ammeter in the car showed the 18 amps so I got the clamp on out to check. It was real close to the in car meter at high or low RPM. The in car meter did not show anything before I changed back to neg. gnd. Part of the wiring oddity. The meter was wired out of the loop. I've adjusted the third brush only once when I installed a FP reg. on my TT. From the little I know, it looks like the brush is rotated way over toward the motor. And right, I won't run it until I get the electrics straightened out.
Remember that the third brush is advanced by rotating it in the same direction that the generator normally turns. If it is fully then in the advanced position - pull it back to the fully retarded position and see if that gets the amperage down and to what level. The main brush assembly may or may not be set to neutral at this point and retarding the 3rd brush will reveal what is happening there. Start by doing that.
Thanks John, I'll get that done later today. I have some heifers to AI first. PK
Well I moved the third brush back all the way and the amps went to -4. I then moved it up a little and got to 0 amps at high RPM. Moved it up a little more and got +8 amps at high RPM. Then nothing. The cut out is open and appears to work. I pulled the generator and it is extremely dirty and oily. One field brush was stuck hard in the holder. This generator is real tired. I'll clean it up and put it back together. Maybe that stuck brush was the problem. Ideas? PK
Pat, none of my Digital clamp on meters will read D.C. only A.C. . Do you have a special one or a special adapter? I'd love to be able to read D.C. Amps with my Meters.
Fred, Southwire makes a Clamp on AC/DC meter Model 21050T that is sold at Lowes. It will read Amperage AC and DC
Fred, It's a Fluke digital, very nice unit. As to my generator, I think I found the problem. The third brush holder insulation to the brush ring is mostly missing. I'm guessing that by moving it the holder contacted the brush ring. Also the holder is broken in half. The windings look like they're covered with tattered cloth. Rebuild time I think. Now the hard part, gen. rebuild or alternator? PK
The insulators on the brush ring can be replaced for a permanent fix since the new ones are made from much tougher stuff than the originals. If you ask him nice - Ron Patterson probably could be a source for a rebuilt brush plate that has all the hard work done. The brush plate insulators being broken is a very common problem and the fix for it is then permanent and likely never to happen again.
Those new insulators are the way to go. I've done a number of them and as John pointed out, it's a permanent fix as they are made from a fiberglass type material rather than the original paper.