24vdc LEDs ?

[Merlin]

Like many of you, I have a 24vdc bus.  Meaning marker lights, tail lights, etc.  My bus is a Prevost which has a goofy 24v harness to the 12v headlights wired in series.  Ticks me off that every time one bulb burns out another will do so very soon.  I've talked with others who own Prevosts in the same rear range.  Same problem.

OK, thus far my solution has been a combination of avoiding driving at night and in extreme cases, using the husky clear fog lamps which put out more light than the headlights do anyway.  Not aimed very well however.  Sorry for the blinding light, but you will know who to blame if you can catch me!!

Now I'm getting serious about replacing the markers and tail lights with 24v LEDs.  Found markers that will fit, but the tail lights are still bugging me.  The standard incandescent 24v bayonet base bulbs there now tend to burn out often.  Overheating is the issue, I'm almost certain.  The bulbs are on when I have the parking brake on and the engine is running.  Meaning, the bulbs get a good bit of "on" time at start up and shut down.  Also they come on when the Jake brake activates even when I'm not pressing the service brakes. I thought the little cyclops light was the only one activated by the Jake, but people following me say differently.

The overheating in the rectangular Bosch enclosure is enough to melt and deform the interior of the housing.  I've tried to use as low a wattage 24v bulb as I could get my hands on to see if the melting would cease.  But nay.  Last summer, I replaced all of the Bosch light housings (not the lens covers which never melt).  Even with the lowest wattage bulbs that I could locate, I'm still getting bulb failures and some heat distortion of the interior housings.

I've had it with continual rear light failures.  It is time to go with LEDs, but so far I've not been able to get my hands on bayonet based LEDs in 24v that will fit.  Another concern is brightness even if I can locate the correct bayonet base size in 24v.

Next thought is to hunt for a flat array 24v LED panel that will fit the rectangular openings.  Maybe even put the array behind the present red and yellow lenses, which probably would entail some Dremel tool work on the interior of the housing.

Sigh ... anyway ... am I alone in this project?  Or am I attempting to reinvent something that has already been solved by fellow busnuts?

Merlin

[stevet903]

There are some 24V LED bulbs here : http://www.superbrightleds.com/cgi-bin/store/commerce.cgi?product=OTHER

There are also a number of posts about the pros and cons of using LED bulbs in place of incandescent in a fixture approved by the DOT for an incandescent bulb only....

[Sean]

Bayonet-base and other style retrofit LED "bulbs" are not legal for use on the highway.  You need to replace the entire fixture, lens and all, with an approved LED fixture.  Lots of styles available, and I'm pretty sure there are even drop-in replacements for Prevost.

You can find tons of 12v retrofit LED bulbs because, legal or not, lots of people who either don't give a damn about or simply don't understand the law will buy them from unscrupulous sellers who conveniently either omit or simply downplay the "off road use only" disclaimer on the product.  But you are unlikely to find them in 24v, because here in the US most 24v vehicles (outside of the military) are commercial, and no commercial operator can afford to run non-DOT lighting on a vehicle.

HTH.

-Sean
http://OurOdyssey.BlogSpot.com

[belfert]

As far as the headlights go I would switch to a relay system so you can use 12 volt lights in parallel instead of series.  This assumes you have a source for 12 volts like a Vanner.  I would not center tap the batteries without a Vanner.

[Merlin]

Thanks fellows.  My gut feeling was that the available 24v LEDs in bayonet were not "street legal".  Putting such a bulb behind a plastic lens may be very dim.

I do have three Vanners that will give sources for 12v. One is tucked high in the engine compartment so, yes, there is the source for 12v back there.  if I send the 24v to activate relays for stop, turn, night operation, and reverse lighting then my next battle is to locate DOT approved 12v LEDs to fit into the rectangular lens housings.  I'll phone Prevost parts people to ask if the old style rectangular tail lights are available in 12v lights.

So far a search on the internet has turned up many truck LEDs but none are the shape that I need.

As to the headlight situation, I got an email from a friendly busnut just now that gave me an idea.  That is to purchase two small 24 to 12v converters and splice into the existing wires which will stop the need for a series arrangement and headlight bulb mass failure.

The alternative is to install a set of 24v activated relays and pass 12v through from the house battery system via a Vanner that is somewhere in the middle of the bus.  Prior to sealing up all the bays and basement dividers this would have been a piece of cake to run the wires.  Now ... a mouse would have a hard time finding enough space in that area.

Since I rarely post on here, but a few fellows may remember me from years past, I want to announce that the conversion is DONE.  OK, as done as I'll ever be able to do.  May be a few tiny things that a so-called professional converter would claim as "unfinished".  But if it passes my wife's inspection I say "good enough".  We are full-timing after ten years of converting.  Every RV park that we visit has a new bunch of curious people wanting to see what's inside.  So far the comments are positive and some even ask why we did it ourselves instead of just buying one from a professional converter.  I'm unable to articulate a reasonable answer to that one without insulting the owners of stick and staple RVs.  Being a quiet person, I simply nod and say it was fun.

Merlin

[Sean]

... As to the headlight situation, ... purchase two small 24 to 12v converters and splice into the existing wires which will stop the need for a series arrangement and headlight bulb mass failure.

The alternative is to install a set of 24v activated relays and pass 12v through from the house battery system ...

There is another alternative which is to convert the headlamps to 24 volts.  I don't know what kind of headlamps you have, but if they take replaceable bulbs such as an H4 these are available in 24v from Hella through a number of online retailers.

If you have sealed beams, Hella and others also make "conversion" kits consisting of an approved reflector/lens assembly that is a drop-in replacement for the existing sealed beams, and accepts replaceable bulbs, which can then be purchase in 24v as above.  The lenses on many of the conversion units are high-impact plastic which, while subject to crazing, are otherwise more resistant to damage than glass sealed beams and will probably last the lifetime of the coach.  Carry an extra bulb or two because you won't find the 24v ones on the road.

BTW, I'm not sure I understand why the series arrangement you have now is hard on the lamps.  Does this have a center-tap connection to the batteries between the series-connected lamps, as is done in MCIs?

-Sean
http://OurOdyssey.BlogSpot.com

[stevet903]

Here's another option if you have the extra $$$ hanging around-

http://prevost-parts.com/index.php?categoryID=588&category_slug=prevost-xl-led-conversions