A Question from the Electrically Challenged

Greg Jones

Greg Jones

Well-known member
Can I add an alternator (6V) and keep everything else stock, ie, coils, timer, etc?

Reason for this is my generator is toast, and a friend happens to have a Model T 6V alternator he is not using.....
 
Is it a gear or belt driven unit? Is it a one wire alternator with a built in regulator? If so, the one wire goes directly (a fuse in line is a good idea!) to the battery or a HOT post on the starter switch or junction block. You may encounter issues with the ammeter/wiring as well. Im doing the same job right now with a 12 volt unit... ws
 
I believe this unit is a one wire with built in regulator, and gear driven. I just rebuilt the engine and transmission and was absolutely anal about setting up the magneto. Used the mag gap guage, went over it meticulously. New recharged magnets and rebuilt coil with Anderson timer. I can start the car on magneto (hand cranking) but on acceleration the car sputters and backfires so I switch it to battery and it runs smoothly. Now I find my generator is kaput. That is why I want to temporarily run the alternator with the stock coils and Anderson timer. Just to charge the battery while running, and until I can sort out things with the magneto and generator. (I kind of suspect the coil box is shorting at high rpms.) I am heading overseas for a number of months and this is kind of a cheap quick fix (if it works OK) until I get back. So if I understand correctly there should be no problem running the alternator rather than the generator with the stock set up. Correct?
 
Should be easy... just make sure the wire to it is from the battery. The regulator will turn it on and off. Thats why you should also put a fuse in there. I would bypass the ammeter at least for now. Im using a voltmeter on a 12 volt system; lights, starter, alt, battery ... your mag problem really sounds like a ****** connection. Easy to check the mag with an A.C. ANALOG (only) voltmeter... about 6-32 volts A.C. At least that will prove on side or the other... ws

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If you notice, my VOLTMETER has a switch in the line so that the meter will work on BATT or MAG. Your ammeter may not take the initial start charge surge.. 40 amps maybe?
 
Thanks, that is very useful information! Yeah, you're right about the connection and the magneto problem or at least that is what it acts like. I just haven't found the problem yet. Work crap keeps getting in the way of my fun. When I do find the problem it will be a simple one-they always are.
 
By the way, here is a picture of the old girl taken today. Just so you know what she looks like. That is ALWAYS important.
 

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That '27 is a gem! Sold mine a few years ago to a pal. It had wood wheels. I always liked them with color paint! Mine was dark blue and black fenders. ws
 
I run a 6 volt alt. on my 27 Roadster. Pulled the second junk generator and installed the gear driven alt, hooked up identical to the gen. Generators hate me and the feeling is mutual. I already had a 30 amp ammeter so no changes there. Works great, had a 6 volt alt on my 28 A also. Big advantage is being able to run halogen bulbs. Starts better too with a fully charged battery!
 
Part of the problem with some alt's is that the Model T motor runs too slow for them. If you have a stock Model T that in high is doing 35 MPH your crank speed is around 1400 rpm which is about what the gear on the alt is turning also. Figure that a lot of your driving will be in the lower MPH/RPM. Check and find out what the output of the unit is at those figures.
 
I was always under the impression that alts arent so much speed dependent as a generator. Once the alternator is locked into a run situation (fields excited) it should almost produce whats needed at almost any speed. if the speed does decrease below the field excitation rate, it will shut itself off until the speed is back up. Mite mean the difference between chugging around town and taking off in low gear. Still tho, a few seconds at 40 amps beats an hour at 5 qmps. I am refering to a 12 volt unit tho... Case in point... these guys are on my boats. Idling at the lock lets say, the voltmeter all of a sudden is showing 12 volts; unit it off. Throw it into neutral for a few seconds and rev it up itll turn back on and stay that way until the idle/load drops/rises. Four 12 volt batteries in parallel does hold the load for lights, gps and radios tho... ws
 
When I 1st start mine, it needs to be revved up slightly to excite the alt. It never loses the "exciting"??, if I can use that term, until it is shut off. After starting, it charges higher for a little bit then gradually drops down to just above center on the ammeter.
 
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