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Author Topic: 24 volt headlights are just too dim  (Read 3985 times)
Fredward
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« on: July 12, 2009, 08:52:58 PM »

Why are the stock 24 volt headlights on the MC-5 so dim? I have not tested for voltage or checked grounds yet. Mine are consistent, all the same brightness - not very bright. Is this just the difference between Tungsten filaments and today's Halogen with fancy lenses?

Seldom do I run in the dark, but man are those headlights dim. Can't believe Greyhound ran these things on the road with passengers at night.

Fred
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Fred Thomson
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« Reply #1 on: July 12, 2009, 09:10:32 PM »

Fred, when you check your ground and voltage check the lamps you may have 28 volt military lamps   good luck
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« Reply #2 on: July 12, 2009, 10:39:37 PM »

Your bus may have been converted to 12V lamps and someone put 24V bulbs in place. Just a thought.
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bobsw
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« Reply #3 on: July 12, 2009, 11:08:46 PM »

My mc-7 are also dim. 24 volt. they just don't seem to project out even on high beam. I just don't drive at night unless I have to.
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« Reply #4 on: July 13, 2009, 03:59:51 AM »

Regular old incandescent lights of a certain era just simply are dim compared to what we are used to with halogen and other high intensity bulbs.  My 5C has the 12 volt conversion and halogen rectangular bulbs.  I haven't driven at night, but even with those I expect some auxilary lights are going to find their way up there...

Brian
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John316
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« Reply #5 on: July 13, 2009, 04:43:00 AM »

I know about the dim part. Our DL3 headlights were very dim, so we did the conversion kit and upgraded to the very nice E style. Now we can see!!!

God bless,

John
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RichardEntrekin
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« Reply #6 on: July 13, 2009, 09:25:24 AM »

Get out the voltmeter.

If you don't have 13 or better at the lights on a 12V system then you do not have the voltage the filaments were designed for. The efficiency curve is not linear, meaning a 10% drop in voltage is much more than a 10% drop in brightness.

The low voltage is product of long wire runs, light gauge wire, and old switchgear.

If you don't have good voltage at the lights then install relays to get the voltage up. Also make sure you have a GREAT ground for the lights. The relay project is one of the best 100 dollars and day of labor you can spend on your rig.
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JimW7
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« Reply #7 on: July 13, 2009, 06:52:32 PM »

I switched my 7 over to 12v rectangular halogen.Much easier at night. My old 24v's, even though new, were just too dim. I didn't think about it until I was done, but are there such a thing as 24v halogen? It would save you some trouble. Jim.
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Lin
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« Reply #8 on: July 13, 2009, 07:13:42 PM »

These are available in both 12v and 24v.  I do not know what they cost though.

http://www.truck-lite.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&storeId=10001&productId=64057&langId=-1
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Fredward
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« Reply #9 on: July 13, 2009, 08:58:09 PM »

Yah I'll do some voltage checking. I just washed it up and put it back in the shop. Also might look into 24 volt halogen thanks for the link Lin.

Jim - Nice to see you on the board! Your MC-7 is one of the nicest I've seen.

Fred
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Fred Thomson
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« Reply #10 on: July 14, 2009, 06:55:47 PM »

Dim headlights are almost always the result of a poor ground in the HL wiring system.
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« Reply #11 on: July 14, 2009, 08:46:27 PM »

Fred,

Don't know much about MCIs, as I'm a GM guy.

But here's another option.....

Use a 24V to 12V voltage reducer, also sometimes called an equalizer (Vanner is a popular brand) to reduce your headlight voltage supply from the 24V to 12V.  On my GM 4905 all the headlights wiring could be pulled in about an hour, especially if you used the old 24V wiring to pull the new 12V wiring.  Replace with larger wire for the 12V headlight system.  Make sure your running lamps and taillamps, etc....are separated from the headlight system so you don't blow overload the remaining 24V system(s).

Walla, 12V headlamp system and you can now use 12V Halogen lamps.

Just a thought, and another option.......

I personally still have the 24V headlamp system and use the  European patterned Cibie E-code H43 & H1 headlamp system. 

On high beam, I can see a stop sign a mile away.  Search the Internet and check out the Cibie systems.  Yes they have them in 24V and they will turn the dark night into day (with out blinding oncoming traffic)....it's all about "light patterns".
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« Reply #12 on: July 15, 2009, 09:25:15 AM »

If your talking about the lights on with the switch their running at 30% voltage only make sure your switch is turned on and your getting 26-28 volts to headlights and a big difference in light output if you have a photo light meter you can use you will see a big difference in output.

LarryH
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Tim Strommen
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« Reply #13 on: July 15, 2009, 11:53:39 AM »

Dim headlights are almost always the result of a poor ground in the HL wiring system.

I agree here most definately.  Check the power first.  Make sure that you are getting all of the volts you are supposed to get across the back of the bulb - then check your wire ends and switches for clean, solid contacts.  If you are using sealed beams, get rid of them - Halogen replacements are available for every type of fixture (even the historic type nowadays).  Before putting in halogens though I would recommend looking at the wiring again (this time wire size).  I would go very overkill with the power supply wires to the headlights (I wouldn't want more than 1/2 a volt drop from the batteries to the bulbs).  You need to make sure that the wires are sized properly for the load size, so that the resistance charactersitic doesn't come into play.

For example, a 12Ga wire has approximately 0.00158546 Ohms of resistance per foot.  Using Ohm's Law:

E/(I*R)

We extrapolate that for a pair of headlights (assuming two 55-watt low beams @ 12VDC) will cause about:

110watts / 12volts = ~9.16Amps

9.16Amps * 0.00158546Ohms = 0.0145Volts per foot drop (assuming they are the only load on the wire).

If you ran a 12Ga wire from the back of your bus to the front (my batts are in the engine compartment), you would have roughly a 0.5075 to 0.6525 volt drop (for a 35 to 45 foot bus respectively, this excludes your chassis as a return path - we are asuming it is a "perfect conductor" with NO corrosion).  On a 12 volt circuit, for the 45 foot bus, this would already be a 5% drop in system voltage at the bulb (which is considered "marginal"), and the bullb will dim very quickly with more resistance (be it from corrosion or whatever).  Assuming you have a corroded ground, wire, or bad switch that is further dropping your voltage - you will have terrible lights in short order.

This is as best as I can manage to illustrate the importance of maintaning your wiring/grounds...


I switched my 7 over to 12v rectangular halogen.Much easier at night. My old 24v's, even though new, were just too dim. I didn't think about it until I was done, but are there such a thing as 24v halogen? It would save you some trouble. Jim.

Hella makes 24V H4/H3/H1 bulbs.  Osram sylvania makes them too (I believe under the "truckstar" label).  I have replaced my 6x8" DOT fixtures with Cibie ECE fixtures (Left-hand-drive beams and with 24V H4).  This was a change from a 12v system, and by leaving in the 12Volt-system-sized wire, and double checking the grounds, I was able to reduce the voltage drop even further (now it's measured out to a 0.23Volt drop, down from 1.9V).

The lights are bright but have a really nice sharp cut that slants away from on-coming traffic, but gets light onto the sidewalk or the ditch on the side of the road.  I also noticed that the lighs have a lot more fill imediately in front of the vehicle, which has allowed me to run without my fog lights on all the time.

Some states may fail inspection if the lights don't say "DOT" on them (ECE would be a fail), but other states (especially where there is lots of fog) allow ECE - and others simply don't fail it if they see ECE.  I think everyone should call their senator and congressman and have them change it for ECE being a global standard.  The beam patterns are better, and it would be cheaper for car makers to only make one type of fixture (ECE is used in more places in the world - go figure, WE are the slow adoptors).  Like in Europe, we now have very high retro-reflectivity requirements for road signs, ECE lights put more light way above the cut-off (so there is a "dark area" where on comming traffic sits), that is intended to illuminate those signs.

With my headlights I can very easily spot the new road signs out here.

-Tim
« Last Edit: July 15, 2009, 05:12:15 PM by Tim Strommen » Logged

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Lin
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« Reply #14 on: July 15, 2009, 01:08:11 PM »

Here's a link to an MCI bulletin about changing 24v to 12v headlights if you want that route.  I checked on the LED ones and they are about $300.  I think I'd wait on those.

http://www.mcicoach.com/parts-service-support/serinfo/serinfo07G.htm
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