Magneto & Battery Connections

[johnfariss]

I recently got a 1913 Studebaker Model 25 Touring Car.  The Splitdorf Magneto has been replaced with an American Bosch DU-4 Magneto (which I am not sure is working).  It does have the Splitdorf switch however.  I would like to use the Dry Cell ignition, or at least have that option.  I have a copy of a Bosch manual which shows hook-up with that--BUT my magneto seems to have only one terminal, while the diagram shows two wires connecting to it.  I cannot tell what the second wire connects to.  Can anyone enlighten me on this?

[playswithbrass]

Hi there the DU4 is a high tension mag and there for is a self contained ignition system,which means no battery is required. You should have a wire that is fastened to the plate that covers the points,grounding this wire will stop the mag from operating thereby stopping the engine. Please post pictures of the mag .May I suggest you get a copy of the Dykes Encyclopedia 1918 this is the year that I read and covers most early ignition systems

Edited May 11 by playswithbrass (see edit history)

[Bloo]

No doubt some Bosch magnetos had a "hot shot" (dry cell) option. Maybe not yours? Lots of systems did have that around 1912. The Splitdorf is a low tension magneto. I don't imagine it would be easy to cross those Splitdorf parts up with a Bosch magneto anyhow. The Spitdorf "switch" is also a coil and a few other incidentals.  If your Bosch mag has an impulse coupler, you don't need batteries, only a kill switch as @playswithbrass suggested.

 

 

[johnfariss]

Thanks.  What is the best way to tell if the magneto is working. . . other than grabbing a spark plug wire while turning the crank?  Photos attached.

[johnfariss]

Here is a 4th photo, showing the points cover better.

[Bloo]

An interesting DU-4 thread:

 

 

 

[edinmass]

DU-4’s Come in single & dual models, as well as twin spark. They are bulletproof as long as you have a good condenser in them. “Old Croak” has all the factory wiring diagrams and parts lists…..here is a link.

 

https://oldcroak.com/bosch-du1-du2-du4-du6-early-pre-ww1/

 

Edited May 12 by edinmass (see edit history)

[Layden B]

To the best of my knowledge and research in Bosch literature, the DU series magnetos came as follows:

 

Independent     That is simple one set of spark plugs, no special starting features.

Dual     Start on battery using a Dual switch coil.

Duplex    Also start on battery but a different system using a Duplex switch coil and different features on the mag than a Dual system.

 

No DU magnetos had the 2 spark system ( Bosch nomenclature  for 2 spark plugs per cylinder). D, DR, Z, ZR, and perhaps others could be ordered with the 2 spark option.

 

 

[cudaman]

For reference, here is a wiring diagram (including the coil box internals) for the original Splitdorf "dual" system in case you can find a good Splitdorf Model D or F low tension magneto and matching coil box.  Note that both wires from the battery go to the coil box, do not ground the battery to the chassis!

 

 

 

Edited May 12 by cudaman (see edit history)

[Bloo]

5 hours ago, cudaman said:

in case you can find a good Splitdorf Model D or F low tension magneto and matching coil box

 

He has the coil box.

 

20 hours ago, johnfariss said:

It does have the Splitdorf switch however. 

The "switch" on a 1913 Model 25 is a barrel shaped thing with the coil inside. That diagram is close enough, except "which post is which" will have to be sussed out. I have seen a diagram like that showing the round coilbox/switch but do not currently have a copy. Only 4 dry cells were used.

 

EDIT: Here's the Model 35 link @TerryB posted in an earlier thread. Despite the 35 having electric starting and lights, the coilbox and magneto stuff are probably the same parts. The diagram on page 11 should get the job done *if* using a Splitdorf magneto. One confusing part is the top terminal on the coilbox/switch. It cannot possibly connect to spark plug #3. It must be engine ground, and if you really zoom in you can sort of see it.

 

https://www.dezosmanuals.com/wp-content/uploads/2021/07/1913-Studebaker-Model-35.pdf

 

 

5 hours ago, cudaman said:

Note that both wires from the battery go to the coil box, do not ground the battery to the chassis!

^^This. Very important.

 

 

Edited May 12 by Bloo (see edit history)

[cudaman]

Here is a Splitdorf dual ignition wiring diagram with the barrel shaped switch/coil unit.  I believe Splitdorf called it the "TS" transformer.  Note that the terminal designations are the same, A is the output from the magneto, 2 goes to the points, and 3 is "ground".  Also note that the only wiring for the high tension EU4 magneto is a switched wire to ground (and the high tension cables to the spark plugs).

 

 

Edited May 12 by cudaman (see edit history)

[johnfariss]

Good afternoon guys!

 

Sorry for the silence--when I got home from church I was exhausted and took a nap.

 

Attached is a photo of the connections on the back of the switch.  "A" connects to the central terminal on the points cover.  "2" is grounded to the chassis.  Nothing is attached to any of the other connections.  Of course I understand that the lower two terminals "B" are for battery.

[johnfariss]

Question: is what they are calling a "spark gap" a vibrator to make pulsating DC current so that the transformer would step the voltage up, like on early automobile radios, and the vibrator atop T-Model (and other early auto) coils?

[cudaman]

Are you referring to the "safety gap" on the top of the coil box?  It's wired into the secondary (high voltage) circuit to give the high voltage somewhere to go if a spark plug fails or some other fault occurs in the secondary circuit.  Otherwise, the high voltage might spark inside the coil and burn out its windings.

 

It looks like you still have the original Splitdorf "TS" transformer module in the dash, but are just using it as a switch to ground to shut off the high tension magneto when you want to shut the car off.  If that's the case, don't hook anything else up to the other terminals, especially a battery.  If you accidently feed battery power back into the magneto, it could de-magnetize its permanent magnets.

 

[johnfariss]

Thans to all!

 

[Tractractor]

Mr. Cudaman, you seem to have a lot of insight on the battery/magneto ignition and I could use some insight. I have a ‘12 Buick Model 29 with the Splitdorf system that has been working great until this last weekend when it wouldn’t start on battery. The battery is hot but there is no spark at the plugs when the engine is cranked and the switch on battery. I can make the plugs fire with the button on the switch and the switch on battery. It does start and run on magneto. I suspect the condenser. How would you trouble shoot this problem? Thanks.

[cudaman]

If it starts and runs on magneto, then the condenser is probably OK.  My 1912 Flanders uses a wooden coil box on the dash (see attached pics), so I don't have any experience with the "TS" transformer that you have.  You say that your battery is good, have you measured the DC voltage between the two battery terminals at the transformer to make sure battery power is reaching there?

 

From your picture, the top terminal (#3) on the back of the transformer sticks out further than the others, has it always been that way?  It looks odd to me, but again I don't have experience with that style transformer.

 

Since it runs fine on magneto but has stopped running on battery, my first inclination is to suspect the switch, which would unfortunately involve taking the transformer unit out of the dash and working on it on the bench.  I have taken the switch out of my coil box to work on it, see the pics, but I don't know if the switch on your transformer is the same inside or not.  Perhaps another member with more experience will speak up.

 

[Tractractor]

Thanks for your response. The terminal #3 has always been that long. It extends beyond the cover and, when the cover is on, that wire is attached outside the cover. With my test light there is power to the battery terminals on the switch and I can make the plugs fire by pushing the button on the front of the switch with the switch in the battery position. The plugs just don’t fire when I crank the engine. I guess I need to investigate the switch!

[johnfariss]

Question about switch terminals:  the magneto is connected to the "A" terminal on the end of the switch housing, and the "2" terminal is grounded.  I would have thought that the switch itself, in the neutral position (up and down, halfway between "M" and "B" with openings aligned for a padlock I suppose) would ground the magneto.  But it does not; instead, moving the switch to "M" grounds it.  Is that how it is supposed to be, or has someone done something to the switch?  If so, how can I get it back to what it is supposed to be?

[cudaman]

The switch/transformer unit you have was originally designed to work with a low tension magneto, like a Splitdorf Model D or F.  It contains a dual wound coil to step up the 6 or so volt AC output of the low tension magneto to enough voltage to fire the spark plugs.

 

You are now using your original switch/transformer unit with a high tension magneto.  The high tension magneto is wound with both low and high tension windings in its armature, so it doesn't need to use the coil in the switch/transformer unit.  The only function that the high tension magneto needs is a switch that connects the "A" terminal from the magneto to ground.  If moving your switch to "M" performs that function, then leave it be, it's fine.  The transformer/coil part of the switch/transformer unit is not being used.

 

You use the switch to ground the magneto when you want to shut the car OFF.  The switch should be open when you want to run the car.  To test if you have spark at the spark plugs, I use one of these in-line testers, it has a light that flashes (dimly) when high voltage is sent to the spark plug.

 

https://www.amazon.com/Straight-Diagnostic-Automotive-Lawnmower-Motorcycles/dp/B0B8VHX5DD/ref=asc_df_B0B8VHX5DD/?tag=hyprod-20&linkCode=df0&hvadid=693334113981&hvpos=&hvnetw=g&hvrand=8133545201445064199&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9022835&hvtargid=pla-1743508282738&mcid=6435e25ff6a7319c8daaef127708b8e1&gad_source=1&th=1

 

 

 

 

 

 

 

Edited May 24 by cudaman (see edit history)

[cudaman]

One other thing - magneto ignitions typically use a tighter spark plug gap than battery ignitions.  Instead of the 0.030 - 0.040 you are used to, try 0.020 - 0.025.