Driving The P15 At Night

[Kilgore47]

Went to the local down town cruise night yesterday.  I usually get home before dark.  But - - A friend that was with me needed to go to the farm store.  That gave me a reason to drive the car more so I agreed knowing that it would be dark before I got home.  Thought it would be OK because the car has been re wired and has new 6 volt sealed beams and a new alternator.  It was not OK.  That was a scary two mile drive home.  I stopped twice and checked to make sure the head lights were on.  It was that bad.  The lights do need to be adjusted but I'm not sure that will make a big difference.  Not driving that car after dark again until I can figure out how to make those lights much better.

 

PS:  Plan on staying with the 6 volt system

[normanpitkin]

I have this problem even with my BMW X5 ,had all the lights tested but it turned out my eyes are old ,not the lights.

[Plymouthy Adams]

I gave you a like for being honest about aging.....it is not a fun process, if we live long enough the majority of us will face this...but if the OP does not have an aging issue.... ensuring good grounds and no voltage drops is in order followed by proper head light adjustment.  

[Kilgore47]

Yes - part of the problem could be old eyes

[James_Douglas]

The new cars. There was an article on this some years ago I read. The candle power keeps going up and those of use with old PAR lights even at 12 volt are going to be blinded by the new ones. 

[allbizz49]

New car lights are terrible.  I hate the blue tint of the light. I guess it's great for the person driving but the rest of us get blinded.  I drive at night and early morning with my old 6v headlights and can see fine. I always make sure to correctly aim my lights. Picked this habit up from working in a body shop for most of my life. It's usually overlooked, even by shops. It can make a big difference if they are out of whack.

[Johnboy]

They sell 6v halogen front seal beam head light bulbs that give a better light at night and draws less juice

Edited October 31, 2021 by Johnboy

[Bryan]

If you have cataracts you can't hardly see at night. Before I had mine done I was bumping curbs turning at intersections at night with my newer Toyota.  If during the day inside whites look dingy, and when you look at ceiling lights it appears foggy around the lights, you probably have cataracts.

[OUTFXD]

A problem I have seen time and time again.  12v bulbs in a 6v system.  They fit,  They Light up.  But they dont put out nearly as much light.

 

Not sure if this is the problem,  but it gives you a easy place to look.

Edited October 31, 2021 by OUTFXD

[Doug&Deb]

Something is out of whack. I drive to work before the sun is up and I have plenty of illumination. Check adjustment and grounds for sure.

[knuckleharley]

6 hours ago, normanpitkin said:

I have this problem even with my BMW X5 ,had all the lights tested but it turned out my eyes are old ,not the lights.

Yeah,that's why I always try to make sure I am home before dark,and my normal drivers are modern trucks with 12 v systems and modern headlights.

 

Then again,as long as I can still see well enough to drive in the daytime,I have nothing to complain about. Since I quit drinking a couple of decades ago,I seem to have no reason to be out after dark.

[Kilgore47]

Being out of alignment is most likely the biggest problem. I'll fix that and try again. But only around the block 

[Bryan]

8 hours ago, Kilgore47 said:

Not driving that car after dark again until I can figure out how to make those lights much better.

 

PS:  Plan on staying with the 6 volt system

Solve it like a standard problem..first have an eye exam and eliminate that, especially if you're over 50. If no cataracts then think about a solution for the car.  If you are rarely out at night, wouldn't spend a lot of money changing the car.  If you need to go out more often at night with it, go with the simplest solution first.  

[Sniper]

5 hours ago, OUTFXD said:

A problem I have seen time and time again.  12v bulbs in a 6v system.  They fit,  They Light up.  But they dont put out nearly as much light.

 

Not sure if this is the problem,  but it gives you a easy place to look.

Seen this too

[greg g]

So are your lights fairly new or have the been there 10 or 15 years.

Are your lights properly grounded? P15 headlights ground to an area that gets all the crap the tires throw up.  Is your sheet metal there in good shape to provide a good ground?

 

Is your cars body grounded by a dedicated ground strap to the frame or engine?  Or you counting on body mounts bolts that have been there for 80 years?

 

Doctor Ohm says 40 watts is 40 watts whether it's 12v or 6 volts.

 

Switch or wires and connections in good shape?

 

Would relays help?

[Sniper]

A 12v headlamp is only rated at 40 watts when being fed 12v. 

 

Ohm's law states Resistance = voltage/current (R=V/I)

 

A 12v 40 watt bulb draws 3.33 A. 40w/12v=3.33A.

A 6v 40watt bulb draws 6.66 A. 40w/6v=6.66A.

 

The internal resistance of a 12v, 40w headlight is 3.6 ohms. 12v/3.33A= 3.6 ohms.

The internal resistance of a 6v 40w bulb is 0.9 ohms. 6v/6.66A=0.9 ohms

 

Now to calculate the current of a 40 watt @ 12v headlamp being fed 6v, I=V/R.

 

6v/3.33A=1.8A

 

Now we can calculate the actual wattage of a 40 watt @ 12v headlamp being fed 6v

Power=voltage times current, P=V*I.

 

12*1.8= 21.6 watts.

 

[knuckleharley]

1 hour ago, Sniper said:

A 12v headlamp is only rated at 40 watts when being fed 12v. 

 

Ohm's law states Resistance = voltage/current (R=V/I)

 

A 12v 40 watt bulb draws 3.33 A. 40w/12v=3.33A.

A 6v 40watt bulb draws 6.66 A. 40w/6v=6.66A.

 

The internal resistance of a 12v, 40w headlight is 3.6 ohms. 12v/3.33A= 3.6 ohms.

The internal resistance of a 6v 40w bulb is 0.9 ohms. 6v/6.66A=0.9 ohms

 

Now to calculate the current of a 40 watt @ 12v headlamp being fed 6v, I=V/R.

 

6v/3.33A=1.8A

 

Now we can calculate the actual wattage of a 40 watt @ 12v headlamp being fed 6v

Power=voltage times current, P=V*I.

 

12*1.8= 21.6 watts.

 

Is any of that in English?

 

Asking for a friend.

Edited November 1, 2021 by knuckleharley

[Sniper]

lol, English translation.  Feed a 12v bulb half it's rated voltage and you get about half the rated output.

[knuckleharley]

49 minutes ago, Sniper said:

lol, English translation.  Feed a 12v bulb half it's rated voltage and you get about half the rated output.

Thanks!

[Sam Buchanan]

I was initially concerned about driving my P15 in the dark after seeing discussion about the old 6v headlights.

 

However, after doing the following:

 

New 6v halogen sealed beams 

 

Making a new ground in the headlight shell 

 

Rebuilding the terminal strip at the radiator 

 

Installing a properly-sized ground cable from the battery to the body 

 

Installing an alternator 

 

Verifying good connections at the dimmer and headlight switch 

 

Aiming the lights

 

The car has perfectly satisfactory headlights. The 6v system works very nicely when everything is as it should be.

 

The terminal strip at the radiator must be in good condition:

 

Edited November 1, 2021 by Sam Buchanan

[Kilgore47]

Bulbs are new.  Grounds are fresh.  Just rewired the car.  I ordered 6v bulbs but I don't remember verifying that they were 6v when installed.  I'll check that and get the multi meter out to verify grounds and voltage while I'm at it.  I will look into the halogen sealed beams.

 

I have another project going now so it may be a week or so before I can get back to the P15.  

 

More news latter

[Sam Buchanan]

1 minute ago, Kilgore47 said:

Bulbs are new.  Grounds are fresh.  Just rewired the car.  I ordered 6v bulbs but I don't remember verifying that they were 6v when installed.  I'll check that and get the multi meter out to verify grounds and voltage while I'm at it.  I will look into the halogen sealed beams.

 

I have another project going now so it may be a week or so before I can get back to the P15.  

 

More news latter

 

I think the only sealed beams you can buy now will be halogen, just make sure they are 6v. There are, however, different flavors of sealed beams, some with higher output than others. I bought the lower priced common ones.

[martybose]

Way back when it was still a 6V car I installed new halogen 6V headlights.  They worked great, but the problem were that the original headlights were only 30 watts, and the new ones were 55W, so the wiring was too small, and the dimmer switch was also getting hot.  Solved all of the issues by installing a headlight dual relay and running larger gauge wiring to the headlights.

 

Marty

[TodFitch]

3 hours ago, Sniper said:

A 12v headlamp is only rated at 40 watts when being fed 12v. 

 

Ohm's law states Resistance = voltage/current (R=V/I)

 

A 12v 40 watt bulb draws 3.33 A. 40w/12v=3.33A.

A 6v 40watt bulb draws 6.66 A. 40w/6v=6.66A.

 

The internal resistance of a 12v, 40w headlight is 3.6 ohms. 12v/3.33A= 3.6 ohms.

The internal resistance of a 6v 40w bulb is 0.9 ohms. 6v/6.66A=0.9 ohms

 

Now to calculate the current of a 40 watt @ 12v headlamp being fed 6v, I=V/R.

 

6v/3.33A=1.8A

 

Now we can calculate the actual wattage of a 40 watt @ 12v headlamp being fed 6v

Power=voltage times current, P=V*I.

 

12*1.8= 21.6 watts.

 

Hmmm.

 

E = I * R and P = E * I

 

From the second, I = P/E. Substituting this into the first equation you get E = P/E * R or R = E*E/P (and P = E*E/R)

 

So for a 40 watt 12 volt bulb your R is 3.6 ohms.

 

Now putting 6 volts across a 3.6 ohm load you get P = 36/3.6 = 10 watts.

 

I think you will find that your 12v lights will put out 1/4 the power if on a 6v system.

 

On the other hand, that resistance is for when the filament is at temperature. Since a 6v system won’t bring the filament all the way up to the design temperature the filament will have lower resistance and the output will be somewhat higher. How much will not hazard to guess but will assume that 1/4 output would be at the extreme end, actual output will be a little better.

[soth122003]

Alright guys. With all this electron ohms laws mumbo jumbo, I went to an expert. Me and Doc Emmitt Brown installed a Mr. fusion reactor and a flux capacitor and wired it to the headlights. Now i don't worry about night driving or accidents cause the lights are so bright I can see into the future and avoid them.

 

Just a little levity to tie the age of the members, the tech of the day and the technical level of our cars together.

 

Joe Lee  

Edited November 1, 2021 by soth122003