6 volt coil 12 volt battery

[1wonton]

My six-volt coil seems a little too weak to fire the spark plugs; will the coil be destroyed if I briefly connect a 12-volt battery just to start the motor (magneto takes over after the engine starts)?

[Rusty_OToole]

I have started 6v cars on a 12v battery with no problems, except after 15 minutes or 20 minutes the coil overheats and quits. Once it cooled down it was ok.

 

12v rough on light bulbs, radio etc so be sure everything is turned off.

[Bloo]

"Magneto takes over after the engine starts" sounds really old. What is it? How sure are you it is 6 volt? In the days before starters when cars often carried dry cells, 9 volt and 12 volt were not unheard of.

 

I would be a little concerned about possible damage, and especially if the ignition parts are the of the unobtainable sort.

 

Edited January 12 by Bloo (see edit history)

[Terry Bond]

What kind of a car is it?

[Jack Bennett]

Your post leaves to the assumption that we know whether you are talking about playing baseball on a football field, or tossing a tennis ball on a golf course.

When you are dealing with any car, it is presumed that the car has ran at some time in its past existence.

You say the car HAS a magneto, so I will guess it is a Ford, or not.

You mention that you believe(?)…….have reason to believe(?)……or know for a fact(!), that the car has a 6 volt ignition system.

Precluding the starter (which really don’t care) if you use a 12volt + or - ground or a 6 volt + or - ground system, the only other voltage sensitive items found on the car are the gauges and the lights.
This, I can suppose that you feel the 6 volts provided the coil, which isn’t part of a magneto fired system, is insufficient to start it, yet I also suppose that the engine continues running with the battery disconnected and fired solely by the magneto.

Sounds to me like you are working with a ignition switch or wiring problem, and were it me, I’d keep that 12 volt battery in reserve until such time as you KNOW what voltage the cars electrical system is comfortable using.

I also suggest that you include the necessary year, make, model and engine of the car your are asking about.

[Fordy]

7 hours ago, Bloo said:

"Magneto takes over after the engine starts" sounds really old. What is it? How sure are you it is 6 volt? In the days before starters when cars often carried dry cells, 9 volt and 12 volt were not unheard of.

 

I would be a little concerned about possible damage, and especially if the ignition parts are the of the unobtainable sort.

 

The Dixie Aero magneto as fitted to the R series Hupps sold in Australia has a winding "coil" inbuilt which is connected to the starter so it gives the magneto a boost on slower crank speeds. Perhaps he has something similar?

Either way 12 volt on a 6 volt winding for any period is going to make it hot and degrade the enamel insulation.

Steve

[Bloo]

1 hour ago, Fordy said:

The Dixie Aero magneto as fitted to the R series Hupps sold in Australia has a winding "coil" inbuilt which is connected to the starter so it gives the magneto a boost on slower crank speeds. Perhaps he has something similar?

Either way 12 volt on a 6 volt winding for any period is going to make it hot and degrade the enamel insulation.

Steve

It also shouldn't be necessary. I wonder what the voltage at the coil is while cranking? I also wonder if the cranking is done with a crank. I have a 1913 Studebaker that is hand cranked. It starts easiest on battery and then you switch to mag. Fortunately it still works. It is 6 volt, originally 4 dry cells, although voltages used were all over the place in that period. Someone posted pics of a 1912 Flanders, a closely related car, and there were a bunch of dry cells in it, and I don't even think they were all in the picture. That Flanders must have been at least 9 volts if not 12. It wasn't unusual. Colloquially setups like these were called "hotshot" magnetos in the US back in the day because they used telephone dry cells to "hotshot the mag" to give you a hotter spark for starting. The setup on my Studebaker is a Splitdorf, but there were many others. I don't completely understand how they work, it must approximate a Kettering-type points and condenser ignition in this mode, but it is too early to really be the same thing I think. Maybe it's just an electromagnet to strengthen the magneto. There were also dry cell powered Atwater Kent ignitions in those days that were points and condenser driving a coil, and those definitely did not work the same as Kettering. Points closing was a spring loaded "SNAP!" affair that was over in an instant, so apparently no dwell time to charge the coil. There was no magneto and you ran on battery all the time. We had those Atwater Kent ignitions on some Hupmobiles here in the US, K and N for sure, and probably others, but I understand Hupmobile put magnetos on when they exported the cars to Australia. Here in the US, hotshot magneto setups disappeared when impulse magnetos came along. You just started on the magneto, and no more switching from battery to mag.

 

In all cases if the spark is weak, the first thing I would be looking at is the condenser(s). Splitdorf mags have a flat condenser sandwiched between the lower and upper half of the magneto. That would be scary to take apart, due to Splitdorf's reputation for pot metal rot. I'm thankful it still works. Although it is possible there may be another condenser in the dash mounted coil/switch assembly for the hotshot function.

 

Edited January 12 by Bloo (see edit history)

[cudaman]

I have a 1912 Flanders with its original, functioning Splitdorf Model F magneto and a rebuilt coil box with a "modern" 6V coil in it.  I have a 12V lead-acid lawn tractor battery under the seat to power the coil for starting, it works fine.  Once the engine starts I switch it to magneto.

 

The owner's manual shows that the original battery was a bank of four 1.5V dry cells wired in series in a crude wooden box, so I made a replica for display.

 

If I had to run the car full time on the battery I would probably switch to a 6V or 8V lead-acid battery to keep from overheating the 6V coil.

 

 

 

[1wonton]

Thanks to all for the very helpful responses.  My 1919 Pierce Arrow has the Eisemann 6-volt DCR switch connected to the Eisemann GR4 dual magneto.  Truck ran perfectly when last parked a couple years ago but now won't start, no high voltage to the plugs.  The ratcheting switch does produce sufficient voltage to fire the plugs but when hand cranking the engine there is not enough voltage.  The points are clean and properly adjusted.   I was just wondering if connecting the 6-volt switch (coil) to 12 volts just long enough to start the engine would damage the coil.  Once started, the magneto will take over and the battery is switched out.

[Bloo]

I wouldn't risk it. It was made to run on 6 volts. On battery it should make no difference how fast the engine is cranking. I suspect a condenser.

 

It looks like there is one inside the dash mounted coil, and a separate one elsewhere for the mag.

 

 

I can't explain why the ratchet switch works when cranking doesn't. Maybe dirty contacts, but I still suspect the condenser more. It looks like this is a low tension magneto, and that dash mounted coil is used in both modes, but the condenser inside the coil is only used on battery. Before taking stuff apart, you could try scabbing another condenser between terminal "R" and terminal "M", or between terminal "R" and ground. It isn't really a good test, and wouldn't prove anything unless it made the engine start. It might. If the condenser inside the coil is shorted this won't help.

 

If the piggybacked condenser doesn't make it run, you could try an old fashioned condenser test. With the battery disconnected, and the switch at center off, and the crank placed so the points for battery operation are open, touch a jumper wire from "R" to "M" for a couple seconds, and afterward probe "R" to "M" with an ohmmeter. The meter should kick to a low value and then go higher slowly and settle to a fairly high ohm reading. This is easiest to see on an analog VOM, but a digital meter should do in a pinch. This test is kind of BS, but if the reading doesn't settle fairly high up in the megohms, the condenser is bad. If it tests normal, it doesn't prove the condenser good. This is about all you can do without taking the condenser out, and if you take the coil apart, it should be possible to clean the switch contacts somehow. If the condenser needs replacing, you need to know how many microfarads the original had. I didn't see that in the documentation. Maybe someone knows.

 

https://oldcroak.com/gr4-ed-2-magneto-parts-service-manual/

 

 

 

Edited January 12 by Bloo (see edit history)

[Jack Bennett]

Fordy, Bloo, cudaman and, yep, 1wonton too, you folks, and folks like you make opening the AACA forum, over any other auto related forum, first thing in the morning worthwhile.

Just because I don’t own, and may never see one, doesn’t mean I’m not interested in literally every make, model, year, body style, fuel source, or any other aspect of automotive architecture.

I have absolutely no idea regarding your material wealth, physical attributes, mental abilities, or even your pronoun selection, or nationality identification (just a bit of period correctness there). I do know though that the gift of information, such as this, is what humanity is all about.

I will close this page, and I will get on with life, but I will take the information that a 1919 Pace Arrow Eisemann 6 volt DCR switch is connected to a Eisemann GR4 dual magneto switch, which is also a ratchet used to produce a voltage while hand cranking the engine to my grave.
That is, as may be as correct as I have restated it here. But, as I said, I will probably never see a 1919 Pierce Arrow, and even if I do, I seriously doubt they’ll let me touch either their Eisemann 6 volt DCR switch or their Eisemann GR4 dual magneto switch.

However, the information is now my property, and, although there are many configurations of Skinner Vacuum tanks and Detroit Lubricator carburetors, and they are not exclusive to Dodges or Fords, but I can now add another drawer to my 3/4 century old library, and label  it I919 Pierce Arrow coil problems.

The only access I have to this drawer is through the many other conspirators in the old car arena who have selflessly shared similar information to move the hobby beyond the rust, rot, grease and grime phase.

Thanks again folks!

 

Edited January 12 by Jack Bennett (see edit history)

[JACK M]

I would be inclined to try a bump start.

But I know exactly zero about this ignition system.

[1wonton]

2 hours ago, Bloo said:

I wouldn't risk it. It was made to run on 6 volts. On battery it should make no difference how fast the engine is cranking. I suspect a condenser.

 

It looks like there is one inside the dash mounted coil, and a separate one elsewhere for the mag.

 

 

I can't explain why the ratchet switch works when cranking doesn't. Maybe dirty contacts, but I still suspect the condenser more. It looks like this is a low tension magneto, and that dash mounted coil is used in both modes, but the condenser inside the coil is only used on battery. Before taking stuff apart, you could try scabbing another condenser between terminal "R" and terminal "M", or between terminal "R" and ground. It isn't really a good test, and wouldn't prove anything unless it made the engine start. It might. If the condenser inside the coil is shorted this won't help.

 

If the piggybacked condenser doesn't make it run, you could try an old fashioned condenser test. With the battery disconnected, and the switch at center off, and the crank placed so the points for battery operation are open, touch a jumper wire from "R" to "M" for a couple seconds, and afterward probe "R" to "M" with an ohmmeter. The meter should kick to a low value and then go higher slowly and settle to a fairly high ohm reading. This is easiest to see on an analog VOM, but a digital meter should do in a pinch. This test is kind of BS, but if the reading doesn't settle fairly high up in the megohms, the condenser is bad. If it tests normal, it doesn't prove the condenser good. This is about all you can do without taking the condenser out, and if you take the coil apart, it should be possible to clean the switch contacts somehow. If the condenser needs replacing, you need to know how many microfarads the original had. I didn't see that in the documentation. Maybe someone knows.

 

https://oldcroak.com/gr4-ed-2-magneto-parts-service-manual/

 

 

 

Checking between R and M there is no circuit, no ohm reading.

[Bloo]

Ok, to clarify, you have everything shut off, and the points open, and you shorted R to M temporarily, and then without the short, you touched the ohmeter leads to R and M, right? And the ohmmeter did not "kick" and slowly go to high resistance or open?

 

If that's true, and it was just plain open circuit, your condenser has left the building. I think you have found the problem.

 

[Zimm63]

Have you thought of pouring a glass of Crown Royal and inviting Ed in Mass over to visit?  He would appear to be an expert in all things Pierce.  

[1wonton]

55 minutes ago, Bloo said:

Ok, to clarify, you have everything shut off, and the points open, and you shorted R to M temporarily, and then without the short, you touched the ohmeter leads to R and M, right? And the ohmmeter did not "kick" and slowly go to high resistance or open?

 

If that's true, and it was just plain open circuit, your condenser has left the building. I think you have found the problem.

 

Yes, that's what I did, however, when I checked the distributer cap I discovered the brush at the bottom (taking circuit from the collector ring) was not making connection to the center brush on the cap.  The brushes are good and I scraped the brass tubes but it did not change anything.  Since the internal appears to be a brass contact strip I don't see any way other than grinding the inside of the cap to see where the connection is lost.  I would never find another Eisemann GR4 cap or magneto so I'm a little scared of doing this.  Any suggestions?

[1wonton]

After further analysis I think I am mistaken about the bottom brush connecting directly with the center distributer brush.  Since this a dual system it appears that the collector brush connects to either the battery or magneto terminal in the switch.  Now, how to dissemble the switch.  I'm quite experienced with destroying antique parts that have survived a hundred years before I got my hand on them.

[DavidMc]

I have run a 12v battery through a 6v coil for a trial and it was OK but I forgot to turn the ignition off and 10 minutes later the coil exploded making a huge mess and some damage.  I won't be trying that again. 

[Bloo]

I'm not sure exactly what I am looking at but, I don't think I would expect those to be connected. Look at the wiring diagram in that Eisemann document. Follow the link to the whole document. There is another version there that is the same, but just missing the ratchet. Everything else is the same. The wiring diagram is quite a bit easier to follow with the ratchet contacts out of the way.

 

Apparently it is a high tension magneto but the high voltage still goes through the switch. In magneto mode, high voltage leaves the magneto and enters the switch/coil on terminal HM. A wire from terminal H goes back from the switch/coil to the distributor center contact.

 

As for how to get it apart, Eisemann shows you what's inside. Have a really good look at the unit. Maybe it will be obvious, screws or something. There has to be a way to get it apart. The biggest problem I anticipate is figuring out what value capacitor to get. For a test, you could try hanging a condenser across M and R. If it starts, it confirms we are on the right path. It probably doesn't need to be that close in value to start and run, but it probably does need to be real close when you choose a permanent replacement. If it is wrong it might chew up the points.

 

 

[Bloo]

I keep looking at this and I think there are more things you should check before taking the coil/switch apart. With no wires connected to the coil/switch, and the switch turned to "bat" position:

 

1) Ohms measurement from H to M (coil secondary winding)

2) Ohms measurement from + to R  (coil primary winding)

 

 

[1wonton]

I figured out how to disassemble the switch (remove two screws on either side of the faceplate, remove one screw holding the switch ratchet handle, then unscrew, counterclockwise, the switch handle.  Then the whole assembly slides out.  Couldn't see any condenser, then discovered it's under the point block.   Since the wires to the condenser are soldered in place, rather than wrecking the whole thing, I decided to test the condenser in place.  I'm no electrical engineer so I'll defer to those with bigger brains than me for comment.  I placed one lead of the ohmmeter in the left side of the points (stationary side in picture one), then the other lead to the metal block (ground?).  This showed no connection, an open circuit.  If I've done this correctly it looks like the condenser is open.  If this is the case, now to find the correct condenser and one that will fit in the place of the original.  Simple........................

[Rusty_OToole]

All cars are the same aren't they? NO they are not. I have started the forties and fifties cars I work on with a 12V battery for testing, when all I had was a 12v battery. But I would not recommend it for a 1919 Pierce Arrow.

 

I would suggest making up a lithium ion battery pack of 6 or 8 volts. It would work for months and could be charged up overnight.

 

If it won't work on 6 volts it is time to figure out why and fix it properly not monkey around.

[Lee H]

I have followed this thread with interest, and I thought I’d share some additional literature from Automotive Ignition Systems, 1920 (alas, no uf rating on the cap). It may indeed be a faulty capacitor, but I have restored many antique radios in my day, and mica capacitors are, in my experience, practically bulletproof. Also, for small capacitances, and depending on the ohmmeter, you may only read infinite ohms from the start…no buildup resistance. And a capacitor doesn’t really “go away” in my experience, unless an internal lead has become disconnected (unlikely). The best way to confirm is to get a relatively cheap multimeter with a capacitance function. Good luck.

 

Edit: I think you mention earlier that it sparks fine with the manual ratchet. I believe that is exactly what the capacitor under the point block regulates…so you may want to review where you’re at.

Edited January 13 by Lee H (see edit history)

[1wonton]

Thanks Lee.  Yes, I am suspect that the capacitor is at fault, the truck ran fine when last started and since I do get sparks when using the ratchet, I see no reason for condenser to just go out.   I'm just not clear as to how to check it while still wired into the armature.  Looking at the wiring diagrams it seems there is no good way to check the capacitor unless it is disconnected from the armature.  If it has only a small resistance value it may appear open but still might be fully operational.  Using the pages you included above I'll recheck the timing, but since there is no reason for the sequence to change, I doubt this is the problem.  Interestingly, the drive plate from the engine is keyed and not adjustable and the GR4 magneto driven end has no means to regulate it's position, so there is really no way of adjusting the timing of the points.

[Lee H]

You probably know this, but only one end of the cap needs to be electrically out of the circuit. Just tracing the schematic, can the other end be disconnected at the point arm, or at the induction coil?

 

if it gives good sparks on the ratchet, I’d highly doubt this cap is the issue. More likely a high resistance connection in the switch somehow.

[1wonton]

Is it possible the condenser in the magneto is weak or open?  Although there is a shocking charge (owowowowow...!!!) at the spark plug terminals there doesn't seem to be enough to create a spark.

[1wonton]

1 minute ago, 1wonton said:

Is it possible the condenser in the magneto is weak or open?  Although there is a shocking charge (owowowowow...!!!) at the spark plug terminals there doesn't seem to be enough to create a spark.

Is there some way to check the condenser in the mag?

[1wonton]

I've gone about as far as I can on this.  Without dissembling the whole switch, I can't tell whether the coil is open, or the condenser is open.  Can someone recommend a rebuilder who may be competent to repair this switch?  I called Marks and Adrians but neither one could take on the project at this time.

[cudaman]

Plugs usually have to use a narrower gap with a magneto than what folks are used to with "modern" cars.  If the magneto gives you quite a shock, then there ought to be enough to jump the right spark gap, IMO.  I run no more than 0.020 inch gap on the plugs in my 1912 Flanders.

[1wonton]

OK, thank Cuda.  I'll close the gap and see if this is the problem.

[Bloo]

Agree. Magnetos always ran a much narrower plug gap than typical points ignitions.