ATV project (need a little help)

[RussH]

Re: ATV project

If you run those in series, don't forget that your engine will need to be reved somewhat to get the full 14.4v. Voltage will be less at idle & low speed. I researched this & came to the conclusion that 2 whites in series or 3 reds in series were the best setup for an automobile. If you have these in parallel, note the amperage will be the sum of the amperages for each LED in parallel, and the LM317 can only handle 1.5 amps max, IIRC. It probably will work better with only 2 or 3 luxeons connected to each regulator in series (MUST be isolated) or parallel.

That allows for rated output or higher from the battery at 12v, which is low but not dead. you need 7v or more for two whites or about 9v for 3 reds AFTER dropping 2-3 volts in the regulator and another 1-2v in the wiring and connections. Note that when in series, there will be different voltage drops in each part of the circuit - start with this: 12v -2volts in wiring, -2v in LM317, minus 3.7v in first white LED, - 3.5v in second white LED, leaving .8v that has to go somewhere.

That .8v would also be dropped in the regulator since it is the only active component than can do something with it. Although ground may not necessarily be zero volts, it should be close. You can expect a small voltage difference between your rear bumper (ground) and the negative battery terminal (ground by definition) just because of all the small connection resistances in between.

 

[Justintoxicated]

Re: ATV project

actually the bike is only AC power. I have a 200 watt aftermarket stator. Im not concerned about the lights being bright at idle....They flicker somewhat but thats ok, they get brighter as I rev up the engine. Don't forget this is a 2-stroke ATV which means to get anywere fast I have to be on the throttle and in or near the powerband anyways. Im not using the lights as headlights, I have 2 75 watt halogens for headlights using those projector sytle bulbs. I wish I could afford HID setup, but its just not practical right now. Your right about the lights, 3 would be pushing it for 1 watt and 2 for 3 watters, It ran better than expected with 2 lights on each regulator (before the defective regulator toasted my RED. I have all the components for the circuit and will finish building a new one tomarrow.

However, I have coolant leaking into my crank case after the disaster trip this weekend /ubbthreads/images/graemlins/frown.gif So now the ATV will be down for some time. I may simulate it outside with a PC power supply. What happends if I run DC power into an AC-DC voltage rectifier? I can't start the bike for pictures or it might blow up the engine /ubbthreads/images/graemlins/frown.gif

also 1.25 x .35 (over estimating) is roughly 435ma so I could get by with a 1/2 watt resistor right? This would save alot of space on my circuit board (1, 3.6OHM 1/2 watt vs 4 of them, 2 in parallel, in series with 2 more in parallel) The board is really crowded because im using 8 more 1/2 watt resistors for the 1 amp circuit.

 

[Justintoxicated]

Re: ATV project

Well here they are plugged into my computers PSU...

The circuits enclosure is pretty warm, almost as warm as the LEDs which is kinda scary /ubbthreads/images/graemlins/frown.gif But hopefully it will be ok once I get it on the ATV

why did this come out purple????

Hope you guys aren't running low resolutions they look small to me..

Anyways I tested the circuits, my amp meter only goes to 10'ths of an amp though

RED's will be run at 340ma
Blues (in picture) are running at 1010ma
The VF of one blue is 3.46 and the other is 3.52, they are from slightly different Bins, but both seem to be about the same brightness... I measured a bunch of times...I thought this circuit was supposed to deliver the exact same voltage to both lights, instead it is doing what I origionally thought and allowing each to run at their exact Vf @ 1.01amps...Or can someone explain another reason for this? It IS what I expected but I thoguht you guys said the LM 317T would provide the exact same voltage to each, vs letting them run at their own Vf @ 1 amp!?????????Acording to this the LM317 is pushing exactly 1.01 amp no matter, so it would be ok to hook up different color Luxeons in series (as they would run at their own Vf), it does not seem to be limiting the voltage to allow 1 amp, unless someone can explain these results, I can measure again and get the exact same results seems to me I am actually regulating the current, so hooing up a different color 3 watt would be ok, it would run this added light at 1.01 amps also, and this light would have its own Vf....Someone prove me wrong but these are the results I am getting...

It looks like 1.01 on my multi meter (fluke) so it may be slightly more or less, they should be exactly 1AMP but perhaps my resistor selection was not as exact this time (Depends what the store gets in stock as far as the resistors I hand pick) My only concern is the project box enclosure, however I imagine that sharing the voltage with the REDs could possibly put less strain on the LM317 running the blues...Guess only time will tell.. both LM317T's are heatsunk though...

Anyone knows what would happen if the heatsinks on the LM317T's were to contact each other? The heatsinks are attached to the Vout so im assuming it would not matter?

 

[Roy]

Re: ATV project

Don't know why the color changed. You need to keep you pictures to no more that 800 pixels wide. Not all of the CPF members have 21 inch monitors and wideband hookups. Thanks.

 

[IsaacHayes]

Re: ATV project

Turned purple because the blue in your camera was overloaded and shutdown? lol. That blue is insane! That makes me want to finish my RB LuxIII dome light !!!

Keep the colors on seperate power supplies. The 2 RB's are averaging out. But if you put a red in with them it would get way too much current.

 

[Justintoxicated]

Re: ATV project

[ QUOTE ]
IsaacHayes said:
Turned purple because the blue in your camera was overloaded and shutdown? lol. That blue is insane! That makes me want to finish my RB LuxIII dome light !!!

Keep the colors on seperate power supplies. The 2 RB's are averaging out. But if you put a red in with them it would get way too much current.

[/ QUOTE ]

yes, of course, but what I ment was, I think any LED running at 1 amp such as a 3 watt cyan or white or green, would create its own Vf to match 1 amp...I know we already talked about this, but thats how it appears to be working, or else both blues should have the same Vf...I tried swapping the order of the lights (lower Vf first) and it makes no difference, the readings are the same...

I also plugged the blues into the 350ma line, and they were nearly as bright, their Vf dropped to about 3.14V but they were still very bright, just didn't quite have the headache brightness factor, but they ran much cooler...still brighter than my old 1 watt blues though...

Now I just need to find a store that sells metric bolts (little longer than the ones I bought) and the next shot will be of them properly mounted and isolated with heatshrink and rubber gromits /ubbthreads/images/graemlins/smile.gif

Only concern is hot hot the project box seems to be getting, since the HS's on the LM317's see little or no ventilation /ubbthreads/images/graemlins/frown.gif

 

[Mark_Larson]

Re: ATV project

I'm restricted to XGA on most of the displays i use, so please resize your pics smaller.

 

[Justintoxicated]

Re: ATV project

okokok, heh but I have to set up my webserver to do so when i get home, and resize and re-compress them...I'll do it I understand why it can be annoying, but 800x600 are tiny on both of my screens, even 1024 does not look that big...pretty big on my 19 inch though /ubbthreads/images/graemlins/ooo.gif

 

[IsaacHayes]

Re: ATV project

it won't "create" it's Vf, but if one single led is hookedup to a current regulator that is setup for 1amp, it will receive 1 amp no matter what it's Vf as the regulator will adjust voltage until the led draws 1amp..

Their Vf at 350ma, just means when 3.14v is pushed into them, the led's draw 350ma. If you want to draw 1 amp, then you need a voltage of 3.52 to do so. It's just a refrence number meaning you need X volts to draw your desired current. Just trying to get you to describe things with the proper terminology to help understandings.. /ubbthreads/images/graemlins/wink.gif

Re: 3.52/3.42 Vf In a series circuit, each item will have equal current going through it. But if you were to take each LuxIII and run them in parallel to your circuit, you'd find that one has more current going to it.
So as you see running a red and a blue together in series will not allow them each to run at their designed current levels because in series each thing will have the same amount of current going through it. BTW a few tenths of a volt can varry the amount of current buy a large amount too, so god knows how much current those poor reds got!

Re: hot box(no pun intended) Perhaps you could drop the Royal-Blue LuxIII's down to 700ma which will still be plenty bright and could make a big diference in cooling of the regulator circuit box. The LuxIII's should be brigther than your original blue 1w's at any current level, as all LuxIII's are equavilent to premium high-binned 1w's in output at 350ma. And at over 700ma they continue to get brigther. Of course you put a lot of extra engery for little output difference, but you aren't running on batteries...

BTW your bolts won't need to be insulated with heatshrink. A rubber grommet will insulate both sides of the mounting plate, as well as the inside of the hole it is installed through. You might also find grommets or even isolated stand offs (plastic peg tube things) at Radio Shack.
Good luck /ubbthreads/images/graemlins/thumbsup.gif

 

[Justintoxicated]

Re: ATV project

I totaly Understand everything you said, perhaps I was just misunderstanding you previously then...

Thats why the project box contains 2 circuits, one for 350ma and one for 1 amp (or 1010ma actually). Cooling should not be too much of an issue (for the LEDs) since the bike I'll be running 90% of the time and passing air over the heatsinks.
Unless your talking about the heat and current on the LM317T, would dropping to 700ma help cool it down also? For this application I figure I should just drive them as bright as specs allow...Since all these lights will probably last longer than wear and tear on the rest of the parts on the bike, even when driven at 1 amp, like the engine for example;) /ubbthreads/images/graemlins/grin.gif

for the gromits, I can't find any that will fit inside the holes I have drilled, and without a drill press it will be hard to drill them larger. Ill see what I can do, but otherwise im going to heatshrink part of the bolt and slice them in 1/2 or use 2 heh...

 

[RussH]

Re: ATV project

The LM317 will heat up according to how much power it is disappating You can calculate it fom the voltage you are dropping across it. It would actually be better to figure IxIxR (Power = current squared times resistance) but we don't know what the resistance (actually impedence)is for the LM317.
Assuming you have 12 volts at the input of the LM317, you are dropping 3.52 across 1 LED and 3.46 across the other which means (12v-6.98v=5.02v) 5 volts is being dropped across the LM317. 5v x 1.01 amp = 5.05watts. 5 watts is a good bit of heat but should be no problem with some airflow. Note for voltages other than 12v, you can calculate the losses in the same manner as above.
You are right in thinking that the 700ma will not produce as much heat. Notice where I used one amp in the above, if you use 700ma, the above wattages will be 70% of what I figured above. I wouldn't worry about it, you will have considerably better cooling (10x or more) with air flow

 

[Justintoxicated]

Re: ATV project

[ QUOTE ]
RussH said:
The LM317 will heat up according to how much power it is disappating You can calculate it fom the voltage you are dropping across it. It would actually be better to figure IxIxR (Power = current squared times resistance) but we don't know what the resistance (actually impedence)is for the LM317.
Assuming you have 12 volts at the input of the LM317, you are dropping 3.52 across 1 LED and 3.46 across the other which means (12v-6.98v=5.02v) 5 volts is being dropped across the LM317. 5v x 1.01 amp = 5.05watts. 5 watts is a good bit of heat but should be no problem with some airflow. Note for voltages other than 12v, you can calculate the losses in the same manner as above.
You are right in thinking that the 700ma will not produce as much heat. Notice where I used one amp in the above, if you use 700ma, the above wattages will be 70% of what I figured above. I wouldn't worry about it, you will have considerably better cooling (10x or more) with air flow

[/ QUOTE ]

The LM317 is in a project box and has those ratshack heatsinks on it, so it will get no airflow. No matter how fast the bike is moving, the Stars will have some airflow though, up to 70+ mph I suppose. maybe faster, but I can't usualy go too far at those speeds offroad, unless its a drag.

 

[Justintoxicated]

Re: ATV project

Ok, im going to resize the pics soon and ill move them to the first post, but I have a new question for you experts...

I pulled the circuit out of the box to get some temperature readings with my infared temp gun on the LM317T. Thanks to your advice I reduced the current to cool the LM317T..HOWEVER...I started clipping off resistors (run in parallel)...

Temps of LMw17T @ 73 degrees ambient, open (not in enclosure)

Running 1 LED:
1125 ma = the Star got even brighter but I did not leave
it connect for more than 2 or 3 seconds heh.
1000 ma = 220 deg F! too scarey to keep this enclosed
875 ma = 195 deg F!
350 ma = 165 deg F!

Running 2 LEDs
1000 ma = test not compleated, already removed one resistor
decided 1 amp was a bit much for how much light I
need
875 ma = 153 deg F.
350 ma = 126 deg F.


Still blistering hot. but still very bright. The LM317T says it can however handle 125C, but im not sure the project box can! If I clip one more the LEDs will be driven at about 750ma. Or do these temps sound reasonable at 875ma. (runing 2 lights) The temps may increase more over time, but I don't have all day (about 20 min running for 2 LEds and about 10 for a single in the testing), and the bike will not always be producing a constant 12V, it varies between 3-14.4V I do not have room to solder on more resistors after I clip them off.

 

[IsaacHayes]

Re: ATV project

Perhaps find a way to get some air into the box. or get the heatsinks outside of the box. I know ratshack has some project boxes that come with both a plasitc and a metal lid. You could heatsink the LM317T to the metal lid, with a heatsink on the outside of the metal lid to the out side air...

 

[Justintoxicated]

Re: ATV project

[ QUOTE ]
IsaacHayes said:
Perhaps find a way to get some air into the box. or get the heatsinks outside of the box. I know ratshack has some project boxes that come with both a plasitc and a metal lid. You could heatsink the LM317T to the metal lid, with a heatsink on the outside of the metal lid to the out side air...

[/ QUOTE ]

Trouble is that I have 2 LM317Ts in my circuit, the Vout is attached to the heatsink, so they need to be isolated from eachother. /ubbthreads/images/graemlins/frown.gif I also need the boxes to be air tight to keep sand dirt and water out.

 

[RussH]

Re: ATV project

What IsaacHayes said.....The 317 has built in thermal protection. It works better if you can keep it cool, tho.

 

[Justintoxicated]

Re: ATV project

[ QUOTE ]
RussH said:
What IsaacHayes said.....The 317 has built in thermal protection. It works better if you can keep it cool, tho.

[/ QUOTE ]

I understand the advantage of this, but right now it's just not a possibility, perhaps in the future However I can integrate that into a new design.

I fergot they have built in thermal protection, but will they get hot enough to melt plastic or rubber before it kicks on? seems as though the best solution is to simply run more LEDs lol and possibly keep them at 750 or 875ma.
I have an extra RED I could add to the taillight LM317T to keep it cool, but I don't have an extra blue (Yet) however they would not be hard to integrate in series /ubbthreads/images/graemlins/smile.gif.

I'm glad you guys made me aware how inefficient this circuit is.

I REALLY APPRECIATE EVERYONE who has provided helpful comments. This hobby is pretty cool, much better than what I was wasting money on before /ubbthreads/images/graemlins/ooo.gif

 

[gadget_lover]

Re: ATV project

If your project box is plastic with a metal top, re-arrange the components so one of the regulators is fixed to the metal lid (makes teh lid a heat sink) and the the other is fixed to your ratshack heatsink. The second heatsink can be bolted to the outside of the plastic box with a metal plate inside to attach to the regulator.

So you have regulator attached to metal plate (washer, scrap, etc) which is attached to a bolt which goes through the wall of the box to attach the heat sink.

Remember; a heatsink inside a closed box is just a more efficient way to get the air in the box hot. After a very short time it does NOT cool your component any further because the air is the same temperature as your component.

Daniel

 

[Justintoxicated]

Re: ATV project

yes in my next design I will definately try to mount the HS out of the box, or use your ideas of turning the box into part of the heatsink. Unfortunately this time it is not possible. I just need to make sure that I can run it in the box for now (I did not realize how hot those LM317Ts were getting before I designed it like this)