early Dodge Brothers lighting question.

[Guest brian j]

Hi. I'm looking into the electrics of my 1919 Dodge Brothers. In the service book it states the generator nominally puts out 3 amps of power, and at high RPM it's set to put out 6 amps, and no more from the factory.(of course, unless you change the setting/not recommended). That translates mathematically to a 36-72 watt output. Is the output of the generator curbed in any way to prevent an overage of power to the lights? (head/tail/dash/etc.) Or is the power unchecked? What would be the correct modern bulbs for headlights/tail/dash etc? The previous owner to me has 1141 tail light bulbs installed in the headlight sockets. They seem rather puny to me. I would think they would burn out at the wattage the generator puts out. Is it common under higher RPM (72 watts) to have lights burn out? I'm just going through the electrical system to make sure things are in good shape. Thanks

[1936 D2]

You would think there would be SOME type of regulating device in that circuit but if not, the battery itself works like a sort of regulator by accepting charge at differing rates depending on the generator output. Bottom line - be sure there is a battery cleanly connected in the circuit or the bulbs WILL blow!

I do hope one of the electrical engineers chimes in here to help answer this question correctly.

[ply33]

Is the generator on your 1919 Dodge a "third brush" type? If so, then that third brush is your regulator which would be the most common type of regulation in the twenties and into the early thirties. Not sure about the teens though.

A third brush regulated system requires that the battery and generator are properly connected at all times to keep the voltage within range. A bad ground connection on the battery, for example, can cause high voltage conditions elsewhere leading to burned out bulbs and other damage.

[Guest brian j]

Mine is the third brush system,in which the power is adjustable(not recommended to change from factory settings), but according to the manual it says the battery will continuously charge, and has the capability of overcharging, at speeds above 10 MPH. It recommend you pull the generator disconnect fuse, or run the lights, to bring the battery charge down if overcharged. In some cases the manual says you can run without the battery connected, and in a pinch multiple dry cells can be used for a battery, should one not be available. I'm just guessing the way the wattage is controlled to the lights is the resistance of the wires themselves, however high enough amp output could cause problems for the bulbs, or even the wires themselves. It seems as if there is little control of charging in those days. Thanks for the input. Regards

[ply33]

...It seems as if there is little control of charging in those days. ...

Too true. 1933 Plymouth Voltage Regulator Upgrade

And while we are on the topic of lights: How good can those antique car headlights be?

[Guest brian j]

Wow! was there a bunch of stuff on those links. Thanks!

[MikeC5]

Interesting link on the Plymouth regulator mod. It sounds like something that could benefit our fours. Anyone try it or something similar?

[Pete K.]

Yes Mike, The Ford Model A's have the same type generator third brush charging system as the '25 Dodge has. (and others). They do make a "voltage regulator/ cut-out relay" now for the A's, with modern electronics packed into an original looking Model A generator cut-out. The 3rd brush is now permanently set at a charge rate of no more than 15 Amps at full speed and there is no more un-regulated charging/ discharging as in the original system. Check it out at their website, I think it's "Fun projects.com". I think any 12 volt voltage regulator should work on our old Dodges, with a bit of experimentation. I'm getting one for the "A" pick up I own since I drive it a lot and need the headlights now after dusk. I may not re-vamp the '25 dodge though.

[MikeC5]

Thanks Pete. Good stuff to know if this does become an issue. I don't drive it enough yet for it to be on the 'top 10' list of things to work on.

[R.White]

I have just been working on a similar problem.

The switch box on my Austin (since we are mentioning other makes) has a "summer " or half charge switch setting. All this does is put a resistor in the 6 volt charging circuit. A bit primitive, I know, but it works well enough. As it happens, on my car the resistor was originally inside the generator but that had long ago been replaced with a later one which had none because the later cars had the resistor built into the cut-out. Instead of driving about with the side lights on to prevent overcharging the battery, I fitted a 1.5 ohm resistor in the circuit. The "summer charge" now works as it should. Just a pitty about the summer. Worst in 100 years.

The voltage regulator set up would be a more suitable for my Dodge but I would need a 6 volt type. I do wonder, however, if it was good enough for previous generations then perhaps we are fussing too much?

Ray.

[Guest brian j]

Ray, the early systems relied on a bit of vigilance when it comes to maintenance............a lot of things to oil, grease, check, and monitor. Since many of us would like to slightly shrink the number of critical parts we have to keep an eye on, mostly for reasons of reliability on the road, there are a few of us that would like to make improvements. I think most modifications that are considered, are "hidden", to keep the look of originality. Also, they ideally should be able to be returned to original if desired. But if a person is good with maintenance, there is no reason the original systems need be changed, and i agree with your point also.

[R.White]

Brian, I am tempted to improve the efficiency of what the old Dodge Brothers car already has to offer if it can be done discretely. For night driving, I would advocate the use of halogen bulbs. As far as voltage regulation goes; that is governed by the cut - out. The third brush on your generator simply gives you some adjustment on voltage output - in Winter you generally need more than in Summer.

The cut - out is an automatic switch between the battery and the generator consisting of a set of spring loaded contacts mounted on a mechanical rocker, or armature and two electromagnets which pull and push on it. One electromagnet has many turns of thin wire and is connected between the generator output and ground. This is the "shunt" winding. The other electromagnet has a few turns of much thicker wire and is called the "series" winding - this is connected in series with the battery and the cut - out contacts.

With the engine stopped the contacts are held open; a) to prevent the battery from discharging through the generator, as it would try to "motor" it, with serious consequences and to prevent the generator from overcharging the battery when at higher revs. As the engine is started and revs increase, generator voltage rises but at first the shunt winding does nothing as it is connected to an open contact. However, eventually (at fast tickover), the generator voltage will reach a value that would be high enough to prevent current flowing from the battery to the generator but would allow current to flow from the generator to enable the electromagnet/ shunt winding to close the contacts against the spring force and charge the battery.

When the contacts close, the shunt winding is now also connected across the battery, giving a 'latching' action with the battery now also providing current for the shunt winding. This enables the contacts to still be held shut until the battery voltage has dropped to a low level - irrespective of the generator output - as the electromagnet is now being operated by the battery.

The "series" winding comes into play by producing a force on the armature which is proportionate to the current flowing either to or from the battery and which changes direction with the direction of the current flow. When the battery is being charged the force is added to the pull from the shunt winding and holds the contacts firmly shut, then when the generator output falls, allowing current to flow from the battery to the generator, the force will be in the opposite direction and opposes that of the shunt winding. When the forces from the shunt winding and the series winding are of equal value, the armature is released enabling the spring to open the contacts. If the engine is stopped at this point, the battery is safely disconnected from the generator. If the engine is restarted; as the revs rise, the shunt winding will close the contacts again.

One final point. The ignition switch does not disconnect the battery from the generator - it's on a different circuit to the cut - out and charging system.

Sorry for the ramble but once I get started.........

Ray.

[Guest brian j]

Ray, i don't have a cutout on my 1919 Convertible coupe, it was too early.You should see my DB electrical manual......it's actually quite humorous to read about how to deal with over, and undercharging. I do however have the 3rd brush on the generator. I'm playing with the idea of installing a reproduction(solid state) British motorcycle voltage regulator, as it is small, and could possibly be hidden, and the amperage output is lower. It is designed for a vintage third brush generator Not to mention it has the cutout to prevent overcharging. I'm just looking into it. I haven't actually obtained one yet. I'll let everyone know how it goes when i do. Anyway, thanks for the schooling, it keeps my brain exercised. Regards

[R.White]

My mistake, Brian. I assumed you had a cut out. I like the idea of the voltage regulator. So long as it is designed to work with a 12 volt system it could be beneficial. I thought old British motor bikes had six volts.

Ray.

[R.White]

Brian, you may not have a cut out fitted to your car, but as 1936D2 said you would have thought there would be SOME kind of regulating device in the circuit. Is it possible that you have a hot wire regulator ?

For the benefit of anyone who is unfamiliar with this arrangement, instead of an opening contact there is a wire connecting the generator to the battery via the ignition switch. How it works is simple; the resistance of the wire (usually insulated nichrome) has what is known as a positive temperature coificient. This means that when you try to push a lot of amps through it, the wire heats up; the resistance goes up and the current comes back down again. It protects the generator from being burned out by the battery and keeps the battery charged o.k. The resistance needs to be calculated or there is a fire risk.

I once used this set up on my Austin (which had a dud cut out when I bought it) and I used a heavier gauge copper cored wire to good effect. The only thing you need to remember from a safety angle, is never to leave the ignition switched on without the engine running and to disconnect the battery when it needs recharging. It's an old school fix but is not best practice these days.

Ray.

[Guest brian j]

I have the original electrical manual for this car, including wiring diagram. I'll scan the pages pertinent to this question, and post them later. It will be more clear then. There ARE things you can do to control the output, but they are done manually, by the operator.