MTFCA Forum

My new to me T has been modified I am told such that the mag is set up to charge the battery. It also has been modified with the later hogshead/starter. To my knowledge it is not supposed to run on mag directly. It has the later T voltmeter. Currently the voltmeter is not indicating that the mag is producing voltage. Can someone school me on how this setup is at least supposed to work? For example I thought that if a normal T mag is functioning properly the voltage would be higher than wanted to charge the battery. Note that the battery is 12 v and per records the starter has been rebuilt for 12 V. The previous owner is deceased but did leave notes on a number of items. He had the starter done but I believe purchased the car with the "conversion" done on how the mag was to function. Help anyone?

For one thing voltmeters show DC and your mag puts out AC so it won't show. The meter would only indicate if the generator is worming which sounds like your car does not have one.

TWrenn wrote: ↑

Fri Apr 26, 2024 7:27 am

For one thing voltmeters show DC and your mag puts out AC so it won't show. The meter would only indicate if the generator is worming which sounds like your car does not have one.

Meant working, not "worming"..ha ha.
Also...when I had an '11 Torpedo with a mag charger there was nothing to indicate whether it worked or not. Frankly I never was sure it really did work that well.

"For one thing voltmeters show DC and your mag puts out AC so it won't show."

That depends on the type of voltmeter you have. If it's the 'Magneto Meter' by Funprojects that was sold by Lang's and other vendors, it will indeed measure and display the AC voltage output from the Ford Magneto. Lang's still lists it but it's unavailable, https://www.modeltford.com/item/A-MAGM.aspx

( Funprojects also offered a DC voltmeter that fit in the Ammeter panel on the dash, that meter was often installed by those whose cars were equipped with alternators to monitor battery voltage. Those were sold by Lang's with part numbers 5016-6v or 5016-12v for 6v and 12v, respectively. The meter scales were 5.5-7.5 Vdc and 11-15 Vdc for the respective meters)

From the descriptions of the meters you should be able to determine what is being measured on your model T. Best, jb

jab35 wrote: ↑

Fri Apr 26, 2024 8:33 am

"For one thing voltmeters show DC and your mag puts out AC so it won't show."

That depends on the type of voltmeter you have. If it's the 'Magneto Meter' by Funprojects that was sold by Lang's and other vendors, it will indeed measure and display the AC voltage output from the Ford Magneto. Lang's still lists it but it's unavailable, https://www.modeltford.com/item/A-MAGM.aspx

( Funprojects also offered a DC voltmeter that fit in the Ammeter panel on the dash, that meter was often installed by those whose cars were equipped with alternators to monitor battery voltage. Those were sold by Lang's with part numbers 5016-6v or 5016-12v for 6v and 12v, respectively. The meter scales were 5.5-7.5 Vdc and 11-15 Vdc for the respective meters)

From the descriptions of the meters you should be able to determine what is being measured on your model T. Best, jb

It is equipped with the Magneto Meter and says that it is to measure AC volts. As indicated it shows 0 volts at all rpm.

https://dauntlessgeezer.com/DG52.html

https://dauntlessgeezer.com/DG102.html

It is equipped with the Magneto Meter and says that it is to measure AC volts. As indicated it shows 0 volts at all rpm.

That would be either the wire from the Magneto Meter to the mag output on the hogshead isn't connected, or the other lead from the meter isn't on a ground. Or, perhaps the magneto contact is caked with oil/lining/metallic debris and is grounding out the magneto output. Cleaning the contact by removing the magneto post would check that. Finally, the magneto could be dead.

With 12v starter added, your T should have a 12v DC storage battery, perhaps the owner used the AC magneto with an adaptor device, to put 12v DC back to the storage battery, but that juice would be very light amps anyway, about like a trickle charger.

Pictured is the last version of the Hotshot charger available from John Regan. When it is operating, the light will glow. Dimly at low RPM, brighter at higher RPM. The bulb serves both as a load and to protect the magneto. Should the diode fail as a short, the bulb quickly burns out. I've used the system for a few years with my non-generator 1917 and it keeps the battery charged. If you have a lot of starts and run your lights a lot you might want to connect a trickle charger for a bit but I've run a whole touring season without having to recharge my 12 volt AGM battery. I should mention that I don't use a full-size battery, I have a Odyssey PC925 under the back seat.

I have a charging pigtai from the battery tie-wrapped behind the tail lamp. I'll measure voltage at it to see the state of battery charge. 12.8 - 12.9 volts is pretty much fully charged. When checked, my AGM battery usually reads in that range.

If you have access to a analog VOM you can easily check the magneto voltage. You can also check the diode if you suspect it is shorted.

More information to add. I cleaned up the magneto contact and now I have a reading on the magneto meter. That is the good news. However I read about 6 1/2 volts at idle but just 10 volts at RPM verified with my fluke meter. What should I see on the mag at RPM? Needless to say that will not charge the 12v battery! Still do not understand how the wiring is set up such that It will not run on mag. Is it likely that a change was made internally in the coilbox/switch?

Even a digital Fluke meter can be inaccurate used on a T. Seen it. Use an analog meter.
If the reading was accurate, that would be low readings. What is the output reading @ moderate/hi speed?
Switch to mag. Will it still run ok? If the mag output is still connected to the coil box.
A properly tuned set of coils should run ok. A poorly tuned set may not.

Here's a thought and I might missed it in a comment...

If an Etimer has been installed the car it then would run on battery and the mag would be charging the battery. You could open the timer and check what kind of timer your car is using?

The first link Mark posted will take you to several articles. The second will take you to the page which deals with the magneto battery charger. It's based on John Regan's design. When people start talking electronics I get serious MEGO, but I made my own charger and it was easy. I've had different "events" on trips, but never a dead battery. If I could do it, anybody can. It ain't rocket surgery.

Still do not understand how the wiring is set up such that It will not run on mag.

If the mag is putting out current but the car won't run on it, there has to be a loose or disconnected wire, or a switch contact that doesn't contact. Using a test light at various points between the mag and the coil box, or in the coil box, should help you track it down. Be very careful that you don't send current into the mag. Current should only come from the mag. It should never go in.

I have a magneto meter the same as Dan above posted with a picture. The Magneto Meter and my Fluke agree on the voltages at both idle , 6 1/2v and at higher RPM, 10 v. The voltage does not exceed 10v.

...the voltages at both idle , 6 1/2v and at higher RPM, 10 v. The voltage does not exceed 10v.

Your magneto is weak. At road speeds (20 to 30 MPH) it should put out plenty of voltage to keep your battery charged. See the chart here: https://www.mtfca.com/phpBB3/viewtopic.php?t=11870

William you might want to see what the potential gap might be. This technique is not definitive but it will give you an idea of what it could be. Take a small crow bar & place it between the crank pulley & block, leverage the crank forward gently, if you have a significant movement forward it could tell you what might be contributing to your issue. My mentor taught me that 40 years ago. They make an aftermarket bronze piece that goes between the pulley and block as a temporary fix until you decide to do something more permanent. Just a thought sorta old school before we had the net & Tbay to find parts and mainly because we were cheap, wanted to see if we could fix it with what was available & parts were scarce. Best John

JTT3 wrote: ↑

Sat Apr 27, 2024 12:04 pm

William you might want to see what the potential gap might be. This technique is not definitive but it will give you an idea of what it could be. Take a small crow bar & place it between the crank pulley & block, leverage the crank forward gently, if you have a significant movement forward it could tell you what might be contributing to your issue. My mentor taught me that 40 years ago. They make an aftermarket bronze piece that goes between the pulley and block as a temporary fix until you decide to do something more permanent. Just a thought sorta old school before we had the net & Tbay to find parts and mainly because we were cheap, wanted to see if we could fix it with what was available & parts were scarce. Best John

Ah you are referring to the "clunk-clunk" i. e. crankshaft thrust clearance. So the mag is sensitive to clearance. I will check that out, thanks!

Yes if memory serves me the gap should be between 25-40 thou

Using a dial micrometer on the front edge of the pulley I measure .005 movement in thrust. The Model T black book indicates that it should be .002 to .004. It doesn't seem to me at just .001 over spec would make the mag voltage difference that I am experiencing. Unless someone has a simple fix idea I think that I will run on Battery for this year and consider pulling the engine this winter. That will allow me to properly check the main bearings (I did exchange the original rods/no shims with a rebabbitted set) and refresh the mag. Any additional thoughts greatly appreciated.

Your thrust is excellent. No need to look @ the 3rd main.
Hasn't anyone suggested an in car magnet recharge? Search for the procedure using a hi amp DC arc welder. Tom Carnage did some exhausting tests & write up on the subject & the info can be relied on. If the recharge doesnt get you to 30V output, your issue is in the field coil & will require an engine pull to replace.

Yes, Search the procedure Tom has developed after much research and is used with great success for in the car recharge. No need for any compass or worry about reversing the magnet polarity. It's very effective, simple and certainly worth a try!

William,

Before you get too carried away with removing the motor or re-magnetising could I suggest you first measure if there is any DC charge current (NOT voltage)? Now that you've cleaned up the mag connection you may find in fact that the battery is being charged in use, although be aware that with a magneto system it won't be at a high rate.

FWIW the reason I suggest checking is that traditional AC meters will measure average (.636), but be calibrated in RMS (.707), whereas what matters to you is DC volts, which should be very roughly 1.4x the RMS. Thus if you have an AC meter reading 10V then the DC voltage (after a rectifier) will be about right for charging your battery (albeit crudely). There are other factors in play here too, including the electrical noise that a T will generate, and the magneto waveform and how meters will react to that, but for the present these are probably safe to ignore.

Note I make these comments without being specifically aware of how your machine is wired, so it may be that you get no result, however it's a simple thing to check before delving deeper.

Luke.

Well, in accordance with the recommended directions provided in the referenced post I attempted an in car magneto refresh with unsuccessful results. I am confident that I did it in accordance with the referenced procedure using 3 12v batteries connected in series. I used stout battery cables and the no load voltage was 38 volts. I very briefly zapped it 8 times and now I have no output on the magneto meter. I did repeat my thrust measurement at .005 inches with a 1' dial mike before and after the procedure with initially the crankshaft pushed back, the wheels chocked and in high gear. Unless someone has another thought, I will run on the 12v battery for this tour season with plans to pull the engine next winter and go after the mag.

We had a fellow (David Woods) come to one of our club gatherings and demonstrate an in-car charging. It was successful, but did not charge the magnets as much as you would get charging them out of the car. I've attached before and after ECCT readings.

Dave spent quite a bit of time getting the magnets positioned just right before charging. It seemed to me it would be easy to mess up that part.

The best way to set up the flywheel and magnets for in the car charging is to remove the trans cover and then rotate the engine so that the top two small bolts holding the magnets are Parallel with the ground or Horizontal. This positions the magnets in the proper place with the field coils. No need for a compass and looking for a North or South. Tom Carnegie recommends using an electric welder. Careful not to short out against the HH so it's best to use an old valve with stem covered with a rubber hose to make contact at the mag post.. Do Not arc to the mag post... do your stike connection at a ground source. You might damage the solder point or the spring!

Gene,
Thanks for responding I used exactly that procedure as previously posted by Tom.

There is one condition related to in-car magnetizing that I have never seen mentioned on this forum. If you use a prybar or shims behind the crank pulley to push the crankshaft forward, you remove whatever crank thrust that may be present. That minimizes the magnet-to-coil ring gap for a stronger charge.

That's my theory, anyway. Let the debunking begin.

If you use a prybar or shims behind the crank pulley to push the crankshaft forward, you remove whatever crank thrust that may be present. That minimizes the magnet-to-coil ring gap for a stronger charge.

Or reduces the minimum .025" gap to less than 0. What happens then?

Steve, I was suggesting only for charging magnets. Less than 0 would violate conservation of mass.

Mark Nunn wrote: ↑

Fri May 03, 2024 8:20 am

There is one condition related to in-car magnetizing that I have never seen mentioned on this forum. If you use a prybar or shims behind the crank pulley to push the crankshaft forward, you remove whatever crank thrust that may be present. That minimizes the magnet-to-coil ring gap for a stronger charge.

That's my theory, anyway. Let the debunking begin.

I was told that when you charge the magnets it will pull the crankshaft forward. I pushed the crankshaft back against the thrust, put a 1 " travel dial on the end of the crank pulley and observed when I di the first momentary charge, it did pull the crankshaft forward by the same .005 " as I had previous done mechanically.

Steve Jelf wrote: ↑

Fri May 03, 2024 11:42 am

If you use a prybar or shims behind the crank pulley to push the crankshaft forward, you remove whatever crank thrust that may be present. That minimizes the magnet-to-coil ring gap for a stronger charge.

Or reduces the minimum .025" gap to less than 0. What happens then?

Not an issue. OP claims .005 thrust/crank movement.

I'm going to try self adhesive abrasive tape 3/8" wide strips on the inside "clincher" edges of the rim. It's the tape you see on step edges to prevent slipping.

Bruce Compton wrote: ↑

Sun May 05, 2024 2:43 pm

I'm going to try self adhesive abrasive tape 3/8" wide strips on the inside "clincher" edges of the rim. It's the tape you see on step edges to prevent slipping.

Posted in the wrong place.

yep...sorry