Okay - I'm close to having everything on hand for the update to my headlight circuit. Four bright and shiny DC-DC converters. They take in 24v (actually anything ranging from 19v-36v) and theoretically output a constant 13.8v, which should be just right to keep the headlights at maximum bright. I will be using one for each headlight, keeping the same circuitry as the OEM design. These are rated for 40 amp each, so hopefully there is lots of head room.
Here's the question:
The instructions state the following...
It is recommended to use stable DC power for the input power supply If you use the pulsed DC power provided by the generator, please filter it with capacitor before connecting it to the converter.
Is this something I need to be concerned about? I am thinking that they are trying to avoid having the output pulse, causing things like LED lights to pulse. I'm going to use incandescent bulbs for now, which don't usually exhibit problems quite as much as LEDs. But, I really don't want to have my headlights pulsating.
Seems to me that the output from the bus alternator will be tempered quite a bit by the existence of the two 8D batteries in the circuit, so that by the time these converters get the input it will be pretty smooth. Or, am I misreading this and are they talking about installing the filter capacitors after the converters in the output circuit feeding the headlights?
If I should be installing capacitors, anyone able to tell me what size and where they go? Across the lines feeding the converters?
I'm about at the end of my knowledge base once we start talking about installing filter capacitors.
For reference, here is the link to what I'm installing: https://www.amazon.com/gp/product/B01LY8D7U0/ref=ppx_yo_dt_b_asin_title_o00__o00_s00?ie=UTF8&psc=1
The pulsing is AC ripple on top of the 28 volt DC that the alternator is putting out, at 6X alternator RPM. A battery will not smooth it out very much, but you won't see it with your eyes. Your devices are 40 amp, not 40 watt. If they give you a capacitor specification for automotive use, I'd add the cap. They are designed for true DC, from a battery or a solar system, but are also recommended for automotive use, so they should be fine. How many are you using? Typical halogen headlights are 65 watts each, about 5 amps, so four are total 20 amps.
Quote from: bevans6 on February 19, 2019, 04:20:11 AM
The pulsing is AC ripple on top of the 28 volt DC that the alternator is putting out, at 6X alternator RPM. A battery will not smooth it out very much, but you won't see it with your eyes. Your devices are 40 amp, not 40 watt. If they give you a capacitor specification for automotive use, I'd add the cap. They are designed for true DC, from a battery or a solar system, but are also recommended for automotive use, so they should be fine. How many are you using? Typical halogen headlights are 65 watts each, about 5 amps, so four are total 20 amps.
Thanks for the typo correction - I fixed that in my earlier post.
The OEM wiring has four separate circuits in place for headlights - one for each of the four lamps. I guess they took redundancy to the extreme, but I kind of like knowing that if something fails it just takes out one lamp, not two or four. I plan to use four of these converters, mainly to maintain the OEM wiring and keep things simple.
If I'm not going to see the pulsation, then perhaps I'm best leaving things be for now. However, after watching a few YouTube video (if they are accurate) the fix doesn't seem to complicated. Guys are using 6800 uF capacitors soldered across the pos & neg wires going to their LED headlights to fix LED flicker.
Could I do the same thing here, except put them in the lines feeding the converters? I found some 6800 uF 35v capacitors, and if that would help I can incorporate them into the harness I'll be putting together.
I like to use water as a means of visualizing what electricity does. So if you have a piston pump feeding a hose it'll pulsate at the rate it's pumping right? Coming right out of the hose you can see that. But if you run it through a big bucket of water the pulsations just turn into small ripples. That's what a capacitor or a battery does. If you want it smoother than that you put a restriction in the line after the bucket, that's what a choke coil does. Then for smoother yet another bucket and the two buckets and the restriction make what's called a "Pi" filter, after the shape of the Greek letter for pi.
So, if you really want to get the ripples out you could install a choke coil in the line to the headlights. What value? Well now you're getting into the math. Obviously with heavy enough wire to handle the current, then enough turns to block the pulses.
Jim
I've been using this https://amzn.to/2TZgHwk with good results so far. It cleans the 24v to a nice 12-ish volts.
So, $300.00 for converters for headlamps ?
Quote from: eagle19952 on February 19, 2019, 11:17:41 AM
So, $300.00 for converters for headlamps ?
I have four converters at about $35 each. Could probably have gone with the $20 ones, but wanted a bit of extra capacity for safety's sake. Whole project should be less than $200 when all is said and done.
Quote from: neoneddy on February 19, 2019, 08:44:28 AM
I've been using this https://amzn.to/2TZgHwk with good results so far. It cleans the 24v to a nice 12-ish volts.
Looks very similar to what I'm using, only would be large enough to provide for all four headlights. The OEM system actually has four separate circuits, breakers and all, so that each headlamp gets its own feed. I guess they didn't want one failure to take out both sides, and I liked that idea and chose to keep it.
Interestingly, that converter has the same warning as mine about pulsed DC. I'm assuming from your comment that the output is clean enough to run the headlights without noticeable flicker or pulsation?
Quote from: Jim Blackwood on February 19, 2019, 06:42:30 AM
...That's what a capacitor or a battery does. ...
Jim
I take from this that you're saying the batteries should be able to smooth things out enough to run the headlights without problems? (For some reason, in my mind I put batteries and capacitors in the same category. Maybe that's why I keep thinking that they'll handle the potential problem.)
You are still going to have headlights that suck. But anyways, there a guy on Facebook that is parting out a 4905. Contact him for the plug and socket.
Incandescent or halogen lights do not turn on and off very fast. They will absorb any ripple on top of the DC and just stay hot, stay on, without any issues at all. LED's can certainly turn on and off quickly, but may or may not offer a problem - you can always add the caps if you run into a problem. Lots of LED's are just on or off, if they get enough voltage they just are on full blast, and a little more just reduces the current they draw. Others are sensitive to input voltage in terms of light output. I wouldn't add the caps at the input to the devices unless the manufacturer suggests so, they will be trying to smooth out the entire bus electrical system if you put them across the batteries directly. Lord only knows what other loads they might see. Which they might ignore, it's been 40 years since I took this stuff in school...
The original system apparently used resistors to drop the voltage. This means they were passing some significant power for resistors, and individual ones per light would be needed to accomodate what are fairly powerful lights, 65 watts each. Not to mention redundancy. I had a setup like that in my MCI, it sucked. One box per light. You could use one of your converters for all of your lights with 50% over-capacity, two converters, one for low beam and one for high beams, or one for left and one for right, but it's simple to just duplicate what you already have and use the four of them.
I just followed the Amazon links, and may have mis-read that you are using 4 separate converters. :)
Quote from: richard5933 on February 19, 2019, 11:59:03 AM
I take from this that you're saying the batteries should be able to smooth things out enough to run the headlights without problems?
Yeah, I would think so Richard, of course led's are more sensitive to fluctuations so it's hard to say for sure but I'd be pretty surprised if the alternator output caused a problem. In the first place it's 3 phase with a full bridge rectifier so you'll have some overlap on the sine pulses. IIRC that's at about the 45° point which is right at the RMS power point anyway, then those big batteries will tend to suck up the ripple. I think I'd try it and not worry about it unless I could see it.
Jim
Here's the completed converter panel ready for install once the final connector arrives. Old resistor panel to the left.
I did test these with engine running and saw no flicker at the headlights. Much brighter light output.
I'll post a lights-on photo once the install is done.
They should work great for driving in daytime. Once you experience a good set of led headlamps, you'll throw all that in the can.
Quote from: chessie4905 on April 17, 2019, 05:12:56 PM
They should work great for driving in daytime. Once you experience a good set of led headlamps, you'll throw all that in the can.
Couldn't find a set of DOT approved LED lights that would fit in the factory buckets.
We all drove with halogen lights for many years. Since we don't do that much night driving in the bus at all, I'm not worried about the lack of LEDs. For finding my way on back roads, I've got a set of LED 'driving lights' mounted under the bumper. They throw lots of light, but it goes everywhere so they can't be used on the road.
Yeah, I see vehicles stopped and checked for the DOT on headlights. Even inspection stations don't look. Good headlamp enclosures in the buckets are adjustable and have good light patterns, at the very least equal to what you have. If you get negative reaction from opposing drivers, adjust them down a little. Other drivers are your best critics. Everything on the road switching to leds isn't just for saving money or economy. They work better. Talk to a couple of truckers thet have them and get their opinion.
Quote from: chessie4905 on April 17, 2019, 06:10:48 PM
Yeah, I see vehicles stopped and checked for the DOT on headlights. Even inspection stations don't look. Good headlamp enclosures in the buckets are adjustable and have good light patterns, at the very least equal to what you have. If you get negative reaction from opposing drivers, adjust them down a little. Other drivers are your best critics. Everything on the road switching to leds isn't just for saving money or economy. They work better. Talk to a couple of truckers thet have them and get their opinion.
Have you found a set of 5-3/4" LED lights that will fit into the factory bucket? They have a huge back side and need clearance for cooling. Even if you can find one with a good vertical cut off so that it doesn't blind oncoming drivers, I haven't seen one yet that will fit without butchering the buckets.
Cibie lights are probably the best way to add light without having to cut too much, but between the cost of the lights and having to re-wire to accommodate the higher current draw I chose to upgrade what I had to make it work as best as possible for now.
FWIW, I drove a friend's Silverado this past weekend in some torrential rain.
He has a set of "internet LED" headlight bulbs...
Obviously not DOT... every dammed sign was dazzling back like I had the highbeams on, peering into the backseat of every car ahead, light scatter was all over, but more importantly, and quite disconcerting, the light down to the ground to pick out the lane markings in this dark at night storm was total crap.
Oh sure, with the light scattered everywhere up high, you can be easily fooled that these will light up your life...
The other vehicle running with us didn't want to lead and be subjected to the mirror blinding, day or night.
Please be careful that you choose rated, road going lighting, so it is aimed where you need it, and the other road users aren't being blinded.
Happy coaching!
Buswarrior
I have LED's in my Humvee and had to paint the top half black they really pissed people off ;D 1 AZ state trooper for sure
Amen to what you're saying BW - lots of oncoming lights these nights SUCK BADLY... >:(
Lots of the road in my area of the county are two-lane road. No shoulder, just a ditch. Lane markings are horrible. I've almost been run off the road more than a few times by oncoming headlights so bad that I couldn't see the road in front of me. I don't want to be one of those guys. Also doesn't help me see the roadbed if the light is all over the place, like BW said.
The worst offender around here is actually the Sheriff's Dept. When they run with their lights flashing, they have high-powered LEDs pointing in all directions -- traffic passing them can't see anything within 20 yards of the squad car.
This was the kind of situation that brought about DOT headlight restrictions in the first place. A little actual enforcement wouldn't go amiss.
Jim
Weird how buses use 24v with converters to 12v. Virtually all over the road big rig trucks are 12v with 12v starters. My old 1985 KW has 12v system with series/parallel solenoid for the 24v starter. Good Luck, TomC
New buses use a 12v alternator for the head lights ,if I wanted 12v lights on a 24v system the 12 v alternator would be the most simple way to do it adding components is adding more problems
Quote from: TomC on April 18, 2019, 09:26:33 AM
Weird how buses use 24v with converters to 12v. Virtually all over the road big rig trucks are 12v with 12v starters. My old 1985 KW has 12v system with series/parallel solenoid for the 24v starter. Good Luck, TomC
Could it have been to allow for the use of lighter gauge wiring throughout the bus? Can't think of another reason since so much of the industry had been 12v for a while.
Slight money savings. Less strain on starter as it is less sensitive to voltage drop compared to 6 volt or 12 volt.
Butcher headlight buckets?? They have 2 1/4 inch or larger holes at the back, plus about a 3 inch hole in body covered with rubber or rubber like material. There is 6 inches more room behind that, at least on a 4905. As far as sign glare, yes that happens, but adjusting headlamps helps or using a not as bright or lumens leds help. I have 10,000 lumen per pair on my highbeams on the suv. The lower ones are factory hid. The fogs are 8,000 lumen per pair. They all work great, especially the fog lamps. I've had one car give me the high beams on my lights in two years of driving and more than 20,000 miles, half local.
Good bright leds are especially beneficial on rainy nights with lots of opposing traffic and markings on roads faded or worn off. We have a lot of deer here to deal with and it helps a lot.
Aside from being $340/ea, these are some of the slimmer headlights I've seen.
Have you seen these installed in a factory headlight bucket without having to cut the hole larger?
$340 each?? Where are you looking for headlamps? They must be gold plated also. Try these:
https://www.rallylights.com/h5006-hella-5-3-4-round-e-code-hi-lo-conversion-headlamp-kit.html
Then you can install leds rated at 12 to 32 volt of the lumens you desire.
Here are some examples in various lumens rated 9-32 volts: https://www.superbrightleds.com/search/led-products/h4/
I thought we were talking about LED lights here.
I know that there are other conversions available, such as the Hella and Cibie, and those you linked to. But those are not LEDs. They would be easier to fit into the buckets than LED lights though, and the only thing I'd want to do is upgrade the wiring to accommodate the increased current draw of those.
Even the ones you linked to would end up being
You buy the light housings, which is what they are. You then install the type of h4 bulb of your desire. Incadescent, halogen, or led. You go down and pick the one with No bulb. Or if you want other than led, they give you a list of options. However those selections are all 12 volt.
In my research, it didn't seem as so simple as sticking an LED lamp in the Cibie housing. Seemed like the lamp needed to match the houding, as the light characteristics of the LED bulbs are very different than the typical H4 bulb.
I've also seen where using a cheap import LED bulb in an otherwise approved housing can result in a horrible light pattern output.
I've seen those LED H4 bulbs at the parts store, and every one of them says "not for highway use".
Not trying to be difficult, but I've been blinded enough times by these cheap import bulbs from oncoming drivers. Some of them were so bright they probably didn't even notice me flashing my lights at them.
What surprises me most is how prevalent these things are despite not being legal for use on the road.
Good optics are not a happy accident. Much time and effort goes into engineering a good reflector and lens, and if the location of the hot spot in the element moves by even a very small fraction of an inch, the optics become garbage.
Now look at how the emitters are made and compare the hot spot of an incadescent, a halogen, and an LED. The LED emitter is very different and is spread over a much larger area. So the light is not going to come from the same place and it isn't going to be reflected the same. The pattern will be off and it will have a lot more spread and the cutoff, if it exists at all will be much higher than it should be. The bright light will be out of bounds and will blind oncoming drivers.
A proper reflector and lens for an LED light has to be designed for the LED emitter in the first place in order to work the way it should.
Jim
Some of the leds can be rotated in their sockets if the pattern isn't correct. Get the bulbs through Amazon. If the pattern causes every car you encounter to run off the road, crash and go up in flames, then return the bulbs. The good leds don't cause the issues that the Walmart ones do. Besides, the idiots that buy the cheap ones so their cars look cool. They have no clue about patterns or adjustments. Proper time spent after installation to adjust pattern will give good results.
The final connector arrived today - got everything installed and I'm impressed. Maybe not as much light as LEDs, but certainly a huge improvement over what we had before. I'm calling this project a success.
I did order some properly colored & striped wire, and I plan to rewire between the panel and the headlights sometime this summer to increase the wire size. After that I can reconsider my options for improved lighting moving forward.
Just a quick update after a few days of driving with the new setup...
The new setup did away with the DRLs, so I've been running with lights on most of the time. Headlights are noticeably brighter and much more useful. Converters run cool to the touch with no sign of heat building up.
For now I'm calling this project complete and successful (but subject to future upgrades.)