An Auto Brake Light led Mod

After FINNALY getting bright enough replacement 1156-7 type bulbs in my car, that left the middle stop light, which used a 194 type connection, and a not very bright bulb.
the 1157 32 led replacements were about as good as a 1157 but not as good as a 2057, which i replace 1157s with usually, so i needed a extra bit of brake jucice to spook the tailgater behind me

you know a HUGE advantage of the leds is they REACT immediatally, instead of in a 30th of a second, they are always talking about what 30th of a second is at 60mph, and if you ask me the DOT should take that into concideration, when they approve of this stuff.

well enough said, here is the pictures (caption below)


4x 1W red leds, mounted to a lightweight aluminum plate, would just fit in this thing without ANY alteration of the original stuff, so it could be reverted when i get that fix it ticket
6 would be just about right for the regulated 14.4v that the alternator puts out, but with 5 , and a bit of resistance, it would be better Balanced, under different voltages , with 4 and a LOT of resistance , i would need fat resisters, and a lot more resistance, but it would be very similar in output at 12-15v even, and more than that it would FIT.


the 194 type connector, was made with a VHS tape tab (hunk of plastic) and copper wires wraped around it, then bonded with j&b weld (not quick)


you can see the wires are stripped far back, so a full 2x wrap goes around the resister, if the resister gets hot enough to melt the solder (it shouldnt if rated proper) the full wrap will insure that it doesnt get sdisconnected.


the resister calculator said about 15-20 ohms and 2 Watts for the resisters, i aquired 6 10ohm 1W resisters, and only used 2. once i tested it IN the car, (before final assembly) i realized the wires leading to the light, and the switch and all reduced the voltage at LOAD enough to only need 5ohms of resistance 2x10ohm parelleled.
with 6 i could make up 5-10-20 if needed.


so there it is done, and heat shrinked, no pics of it in the car.

one thing i didnt think about is WHY there is a rubber seal around the plastic module.
it was so moisture could not get back in there, and FOG up the glass, well it was all fogged up by the time (2am) i got finished, and i ended up Sealing the Fog into the thing (dum dum dum) anyways, i had to open up a edge of the rubber and defog it, then close it up again.

no bridge rectifyer in it, so it must be connected in proper polarity,it ONLY runs when the brake is pressed , so there is not 2 sets of resistance for it.

Excellant job!

i had this thought once that goes along with it.
we got solar, and led and florescent lighting here, to save power. but in the automobiles we Feel like the power there is totally free.
But the heck if its free, the motor may have to run anyways, and it may not be much power to pull 60A with a generator, but if that was a good idea, then we should hook our cars up as generators for the house
SEE
its not a good idea at all to waste power in the car, because as a generator , were paying a auful lot to fuel the thing, compared to hydro, or mass coal, or natural gas, or nuke power.
were powering the items in the car with a gas generator, at $2.50+ per gallon :-O.
On a 8 cylinder 450HP suv that is sucking fuel through a 3/4" hose, and drinks like a fish at idle even, a few extra drags down on the system arent going to make much difference in gas milage. but in the small efficient cars, pulling 60A down off a poor efficiency generator , is just wasting gas.
SO
even the cars could use efficient lighting, and power items to save overall power, and MONEY.

that is my take on it, and with 4-10A of replacable lighting in most cars, its a start. add in the headlights, and well we will be good when gas goes to 6$

Sorry to rain on the fuel efficiency parade, but the reason current draw isn't that big a deal in cars is, as you said, a 60 amp alt isn't much draw on the engine. Car engines are actually very inefficient... Look at the water cooling system and huge heat radiator stuck on the front of each of them just to keep the engine block from distorting and melting down. Consider all the heat and mechanical energy that gets flushed out the tailpipe with every crank revolution - They have to put mufflers and heat sheilds on the exhaust to keep the deafening noise of the super-sonic exhaust pulses (not exagerating) to a minimum and to prevent the heat from catching grass and such on fire.
Small engines are no different... Go take the muffler off a lawnmower, start it up and try to tell me it's not rediculously loud.
If you want to make an engine more energy efficient, there are other ways to spend your time and effort that will net you a much more substantial gain. If you converted all the lighting on a car to LED and/or HID, you might see a 1 or 2 MPG improvement on an already relatively fuel efficient car.
The exhaust for instance... Take the turbine side of a turbocharger, stick it in the engine exhaust flow and connect the output shaft to a high RPM generator. Direct the power from the generator to the wheels via an electric motor (or two), a hybrid style high voltage battery pack, or to charge the regular 12v battery if you like. You will have removed waste energy from the exhaust stream and put it to use. The exhaust coming out the tailpipe will be quieter and cooler, the load on the engine will be reduced - either the alt doesn't need to spit out as much current, or the motors driving the wheels will take some of the load of moving the car. The only possible down-side that I see is that you might get some back-pressure between the turbine and engine, reducing peak engine output slightly.
IMO, LEDs are a better solution for automotive lighting due to shorter turn-on times, greater vibration resistance and much longer service life. Also, their more or less monochromatic nature and reduced heat output allow for some creative lamp/lighting designs and alltogether new applications.

Anyway, on topic, why use a cube of LEDs? A tetrahedron could be cheaper (fewer LEDs), more compact and have a better light distribution, though I guess it really depends on the LED's light output angle. If it outputs at 120°, the 90° edges of a cube would result in a fair amount of overlap between LEDs. Also, if you had one face pointed directly out of the lamp, the remaining 3 would be angled inward toward the reflector.

bobski said:

If you converted all the lighting on a car to LED and/or HID, you might see a 1 or 2 MPG improvement on an already relatively fuel efficient car.

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I just don't see how that's possible. The alternator is going to spin at the same rate (a percentage of the RPM of the engine) and work just as hard, no matter how many amps your pulling from the battery. It's out-putting a certain voltage at a certain current (determined on RPM, of course). The regualtor then measures what goes to the battery and what is "wasted".

ss2nv said:

I just don't see how that's possible. The alternator is going to spin at the same rate (a percentage of the RPM of the engine) and work just as hard, no matter how many amps your pulling from the battery. It's out-putting a certain voltage at a certain current (determined on RPM, of course). The regualtor then measures what goes to the battery and what is "wasted".

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car alternators adjust the amount of current and voltage produced by adjusting the power in the armature... this is why they have brushes....

hizzo3 said:

car alternators adjust the amount of current and voltage produced by adjusting the power in the armature... this is why they have brushes....

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Any links proving that? Have you ever seen an armature outside it's housing? It is usually 3 to 6 "arms" with wire wrapped around each of them. It is basically an electric motor, but instead of applying power to the brush shunts and getting rotational power out of the armature shaft, you apply rotational power to the shaft and get electric power out of the shunts. I'd like to know just how it "self-adjusts" for power output. Brushes are what makes contact with the end of the armature. If you want a good pic, look up pics of disassembled elctric motors. I've been wrong MANY times before, and I'm not trying to be smart-*** here, so don't take it that way, but I'd like to know where you got this from.

Is there a legal liability issue if you are using non-DOT brakelights and are involved in an accident in which someone claims your non-approved lights and/or non-OEM install contributed to the accident?

ss2nv said:

I just don't see how that's possible. The alternator is going to spin at the same rate (a percentage of the RPM of the engine) and work just as hard, no matter how many amps your pulling from the battery.

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The alternator may be spinning at the same rate, but more power is required of the engine to turn it at that speed when a large amount of current is pulled from the electrical system. Turn on your headlights with the engine running and you can hear the difference.

BTW, neat project!

ss2nv said:

I just don't see how that's possible. The alternator is going to spin at the same rate (a percentage of the RPM of the engine) and work just as hard, no matter how many amps your pulling from the battery. It's out-putting a certain voltage at a certain current (determined on RPM, of course). The regualtor then measures what goes to the battery and what is "wasted".

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take any generator, even your dynamo flashlight, and remove the wire off it, its still spinning but the "energy conversion" is not occuring, and so it spins much freeer.
a unloaded dynamo (crank light) spins easy, its the load that makes it "work"

ss2nv said:

I'd like to know just how it "self-adjusts" for power output. Brushes are what makes contact with the end of the armature.

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The difference is in how the brushes are configured.

On an electric motor, the brushes are directly oposite eachother with respect to the armature shaft. The armature has a series of 3 or more contacts for the brushes. There are 3 separate coils on the armature, each connected to a pair of contacts... Each contact has two coils connected to it, but no two coils have the same two contacts. Anyway, as the armature rotates, the brushes make and break electrical connections with the various contacts and thus the coils. This switching effect pulses the armature coils at the appropriate time (with respect to armature angle) to maintain constant rotational force.

In an alternator, the brushes sit one above the other, not across from eachother. Each brush has it's own dedicated contact on the armature, and there is only one armature coil. The brushes in an alternator don't perform any switching - they simply transmit power to and from the rotating armature.
An alternator generates power by spinning an armature with a magnet or magnets on it past coils set around the armature, fixed in the body of the alternator. Moving the magnet past the coils induces current in the coils. Since the magnet is spinning, there's a constant north/south switching in the magnetic field each individual coil experiances, so the current in each coil switches direction correspondingly... Alternating current. This is why they call it an alternator as opposed to a generator.
In the case of the alternator found in a car, the AC current is then sent through an array of rectifier diodes to produce pulsed DC. Since the coils are set around the alternator and not all in one spot, they don't produce pulses at the exact same time. Once converted to DC, the pulses can be added together to produce a fairly even current flow - the low point of one coils production is compensated for by raised output of the other two.

An alternator regulates it's output by adjusting the strength of the armature magnet. Not really possible with a simple permanent magnet, but adjusting the strength of an electromagnet is just a matter of regulating the current flow through the coil.
The voltage regulator in an alternator doesn't directly limit the power output by applying loads or PWM to the output, but rather watches the output and adjusts how much power is being fed to the armature coil correspondingly. Less power means a weaker magnetic field and less current induced in the stator coils (the coils in the body of the alternator). More power means a stronger magnetic field and more current induced in the stator.

Nippon Denso alternator, vintage 1991:

Rear cover removed. The lower half is the rectifier assembly, the upper brown plastic and heat sink part is the regulator, and the orange part is the brush housing cover:

Regulator removed and brush holder removed, brushes and armature contacts visible:

bobski said:

Anyway, on topic, why use a cube of LEDs? A tetrahedron could be cheaper (fewer LEDs), more compact and have a better light distribution, though I guess it really depends on the LED's light output angle. If it outputs at 120°, the 90° edges of a cube would result in a fair amount of overlap between LEDs. Also, if you had one face pointed directly out of the lamp, the remaining 3 would be angled inward toward the reflector.

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well with the engine i have, turning on the AC alone , and it wont get up the hills "safely" at speed. and running the AC on it costs the MPG about 1/5th.
but its a pregnant rollerskate , with a lawnmower engine. so the draw from the alternator is horrendous whats a Turbo and does it get 45MPG on the highway?

the only reason i mention a cube, is because 4 Square stars are pretty EASY to form a cube, and with little materials it can be done. i am sure a geodestic dome would be the best method, its just that cubes are easy, metal at the hardware store, has a lot of 90* angles and stuff.

Excellent info Bobski and VidPro! I didn't really think about it that way. I guess I don't know as much about alternators as I thought! Heh. Learn new stuff everyday around here!