1924 Buick Headlight Resistance

[27donb]

I just finished putting together a combination switch for my 24-45.  Before installing it in the car, I wanted to test it on the bench with a 6 volt battery.

 

I removed the two 21 cp single filament headlight bulbs from the car and wired them to the switch.  But during the dim "low beam" test using the resistance coil on the back of the switch, the coil heated up.  Very hot.

 

I am looking for opinions from those who have the original resistance coil in use on their 1925 (?) and earlier Buick, before the dual filament headlight bulbs and dimmer switch was used.

 

Is it normal for the coil on the back of the switch to heat up that much?  I mean, I know that resistance creates heat, and dimming these two headlight bulbs has to generate heat.

 

But on the other hand, I don't want to set my treasured car on fire.

 

What is your experience with this resistance circuit and coil, and what is normal?

 

I do want it to work as original, and in my state the car inspections even for antique vehicles require original equipment to work.  So just bypassing the coil and having one headlight brightness is really not a solution I would be happy with.

 

The attached picture is an example of what I am using, my actual connections have all been cleaned up.

[Brian_Heil]

Never use it for that reason and that the stock bulbs don't make enough light anyway on low beam to throw heat and voltage away thru that resistor.

 

I upgraded to halogen bulbs.  Each draw about 9 amps (18 total) but they really work and for those times where you get caught in the dark they make all the difference.

[Daves1940Buick56S]

Can you get an ammeter and put it in line? If so, measure the current 1) with the coil out (i1) and 2) with the coil in (i2). Also measure the battery voltage (V) under load, hopefully it won't change too much between the 2, if it's more than 0.5 V then just average the 2 readings since this is just a rough calculation anyway. Then the coil resistance can be found from R = V/(i1-i2), V in volts and i in amps. The power dissipated in the coil is then P = ((i2)^2)*R, with ^2 meaning squared. That will tell you how many watts it is dissipating.

 

Cheers, Dave

[Leif Holmberg]

I have the original switch on my 23-24 and 25 Buick:s but never had any problem,yes the resistens coil will be warm-hot.What you need to do is to check the "black or brown"bakelit plate,if it`s stright there are no problem.But you need to sand or glassblaster the conections as in the picture you show.The coil in the middle are for overloading,when yoyu put the light on it can bi a "click"in the coil but that`s okey.

Leif in Sweden.

[27donb]

1 hour ago, Leif Holmberg said:

But you need to sand or glassblaster the conections as in the picture you show.

Leif in Sweden.

 

As I stated, that is a picture of a coil but not my coil, my connections are clean.

 

The voltage at the resistance is 2.35.

[Leif Holmberg]

I measured the resistens  and it was 0.8 ohm.This resistens are just to cut down the voltage from 6 volt to around 5 volt.If it`s 2.35 ohm it looks a little bit to high.It´s very importent to have the conections very clean when measuring ohm.

[27donb]

4 hours ago, Leif Holmberg said:

If it`s 2.35 ohm it looks a little bit to high.It´s very importent to have the conections very clean when measuring ohm.

 

Nope, the VOLTAGE at the resistance terminal, is 2.35 volts.  The lights are dim.

 

 

All connections inside and out have been sanded and shined up.

 

I just measured the ohms, and I got 0.8.

 

I tried measuring voltages at different points on the coil, and at about 2-3 coils (half way) the voltage is about 4 volts.

 

Should I cut half the coil off, and wire it that way to get the 4 volts?

 

 

 

 

Edited April 13, 2016 by 27donb (see edit history)

[Daves1940Buick56S]

Assuming your battery is 6V, dropping from 6 to 2.35 Vdc means that you are dissipating about 16 watts in the 0.8 ohm coil. If by removing 1/2 the coil you get 4 volts, then assuming the coil is now 0.4 ohms you will be dissipating about 10 watts. In terms of temperature your 1/2 coil will be running hotter (watts per turn) than the full coil did. Look, since no one can see what you have done when the switch is in position, be safe and get a 0.5 ohm 20W or better resistor - like this one on ebay http://www.ebay.com/itm/like/130732290360?lpid=82&chn=ps&ul_noapp=true

 

Cheers, Dave

 

 

[Leif Holmberg]

Instead of a resistor you can use a Diod,they need around 0.5-0.8 volt to open upp,that meens the voltage to your head lights will be reduced with 0.5-0.8 volt.That`s the best way,no heating and can be installed on the same place where the resistor has been conected.Just talk to an electrican and they can tell you what you need,the diod will cost about a couple of $.

Leif in Sweden.

[27donb]

On 4/14/2016 at 1:51 AM, Daves1940Buick56S said:

Assuming your battery is 6V, dropping from 6 to 2.35 Vdc means that you are dissipating about 16 watts in the 0.8 ohm coil. If by removing 1/2 the coil you get 4 volts, then assuming the coil is now 0.4 ohms you will be dissipating about 10 watts. In terms of temperature your 1/2 coil will be running hotter (watts per turn) than the full coil did.

 

Look, since no one can see what you have done when the switch is in position, be safe and get a 0.5 ohm 20W or better resistor - like this one on ebay http://www.ebay.com/itm/like/130732290360?lpid=82&chn=ps&ul_noapp=true

 

Cheers, Dave

 

 

 

That makes sense, cutting the coil would make it worse.

 

I haven't actually "done" anything yet, I am just experimenting on the bench to try and figure it out, checking the voltage at the switch when the lights are in "dim" position.  I didn't actually cut the coil, I just probed it at about half way up the coil, to find 4 volts.

 

Thanks for the link and advice Dave!

Edited April 16, 2016 by 27donb (see edit history)

[27donb]

2 hours ago, Leif Holmberg said:

Instead of a resistor you can use a Diod,they need around 0.5-0.8 volt to open upp,that meens the voltage to your head lights will be reduced with 0.5-0.8 volt.That`s the best way,no heating and can be installed on the same place where the resistor has been conected.Just talk to an electrican and they can tell you what you need,the diod will cost about a couple of $.

Leif in Sweden.

 

Thanks Leif, I was reading about diodes, I will look more into that.

[Pete Phillips]

I have some brand new, old stock 6-volt headlight relays if you think that would help the situation. A lot of people use them to get brighter headlights on the old 6-volt cars.

Pete Phillips, BCA #7338

[dibarlaw]

All my lighting seems to functioning well. I rebuilt all the switch unit and it operates as Leif indicates. All connections cleaned and had the reflectors re-silvered. I did install the halogen bulbs. It did not appear to give me that much more light than the regular bulbs. It does not matter if I used them or incandescent bulbs when I switch to dim I would expect about 1/2 the light intensity. There is hardly the glow of a candle. So yes it is dim!!

[26-25Buick]

I agree with Larry. I guess it depends what you're using to compare them with, the headlights are not spectacular but they are functional.

I've found the resistance coil (overload protection/cutout) in the '26 light switch doesn't chatter with the headlights (with the standard incandescent globes) in either position dim or bright and I can attest to my cutout is working as it had occassion to at one point due to a short in the wiring.

Having a dimmer switch mounted at the end of the steering column where it's subject to road grime especially without the splash guards fitted probably wasnt the finest bit of Buick engineering and any resistance here will not only dim the light output but it also increases the current draw increasing the current/temperature at the cutout.

Yet another suggestion for a fix, hide a fuse box up behind the switch or put a in-line fuse in after the switch so you can't draw too much current.

 

[27donb]

20 hours ago, 26-25Buick said:

I've found the resistance coil (overload protection/cutout) in the '26 light switch doesn't chatter with the headlights (with the standard incandescent globes) in either position dim or bright

 

 

Of course, the 26 and newer models have the dual filament headlight bulbs, with a high beam and low beam circuit, and the steering column mounted dimmer switch.

 

The circuit breaker coil is present on the earlier models also, to protect against short circuits.  But my circuit breaker works and is not in question here.

 

The earlier models had single filament headlight bulbs, with a resistance coil to "dim" the bulbs to act as low beam, as shown in the picture in my original post.

 

Today I bought a ballast resistor from an auto parts store and did a bench test on my setup, and got a similar result.  The ballast resistor was about 1.0 ohms, and gave me about 3.0 volts to the bulbs in the "dim" position.  The coil heated up, but at least it is mounted in a porcelain holder and not out in the open on the back of the switch as the original one was.  I feel a little safer using it.

 

I will not be installing halogen bulbs.  I have found driving at night that the original headlights do an adequate job.  The most dangerous driving at night is at dusk or dawn, or where there are a lot of street lights.  On dark roads and at the slower Buick speeds, the headlights are fine.

 

 

[27donb]

On 4/14/2016 at 10:27 AM, Pete Phillips said:

I have some brand new, old stock 6-volt headlight relays if you think that would help the situation. A lot of people use them to get brighter headlights on the old 6-volt cars.

Pete Phillips, BCA #7338

 

Thanks Pete, but in my situation the concerns I am having is with the resistance "dim" low beam headlight setting, which is supposed to be dim.  My only concern, was how hot the resistance coil was getting, and that the voltage was being cut by almost 2/3.  I wasn't sure if that was typical of others with the same original setup.

 

I already do use 6 volt relays for the headlights and driving lights in my 27-54CC, that does not use the resistance coil for the low beam circuit.

[carmover]

Bob,s completely restored my Combination switch on my 25 and the resistor will start smoking if left in low beam for more than a couple of minutes.

[27donb]

4 minutes ago, carmover said:

Bob,s completely restored my Combination switch on my 25 and the resistor will start smoking if left in low beam for more than a couple of minutes.

 

Good information there, thanks!  Mine does the same thing.

[dibarlaw]

It is timely that this discussion has re-surfaced. I am I the process of rebuilding a switch for the 1925 Master and this has been a concern. I did a post on how I rebuilt my switch for the 1925 Standard. The new cases I purchased from BOB"s are made of more stable material but the quality is poor at best. The one I bought 4 years ago was better. This unit has gas holes, inclusions and is smaller than the original since they probably used a good original to use as a mold. The aluminum shrinkage is noticeable. One has to either re-machine the bore where the contact plate fits. As I have done. And /or file the contact plate as I have also done. The repro switch levers also need rework to fit and operate smoothly. A side note about the fasteners on the original DELCO units. They are #10 30 TPI. Not #10-32 screws which are the common fasteners found today. There was no reference to 30 pitch fasteners in my 40 year old "Machinery hand book". I had to look in my grandfathers 1926 edition of "The Starrett Book For Motor Machinists" (thank you Pa Pa)! There they were #10-30 tpi screws noted.
 I will also add the ballast resistor so I can have a brighter "dim" position of the lights.

[Brian_Heil]

There is also a 'thermal switch' on the back of the combination switch that is the 'fuse'. 

 

This switch has contacts and is mechanical.  Any poor contact surface or low spring load can lead to higher resistance and dim lights or even no lights.  Not certain if the ignition goes through this too.  Need to look at the mech. drawing.

 

I had this switch decide to go 'open' on a late night ride on a country dirt road where you could not see your hand in front of your face.  I got lucky poking around with my hand on the back side of the dash and the switch, where I corrected the contact momentarily and then knew what to work on.  A couple of swipes with the wife's nail file from her purse cured the issue and we got home safe and sound.

 

And, as an edit, I answered my own question I think since the car still ran but no lights so at least my ignition 12V does not go through the thermal switch.  And I may need more current and voltage to fire my halogen bulbs.

 

CORRECTION  6V  (Ha!)

Edited December 20, 2016 by Brian_Heil (see edit history)