led’s and car alarm

I am getting the viper 5902v and it has aux ports I guess. I want to be able to hook up some led's to be activated when I push the aux button on my remote that are placed under all the seats. I plan on buying a bunch of blue led's and hook them up to the battery. I was wondering what switch/box would allow me to send what ever signal out to a switch so that I could turn on led's with a remote button. Thanks for any help, also if anyone knows, does a dodge grand caravan 1999 need a bypass module for a viper 5902? My local car guy said probably now, but just want to see if anyone knows for sure

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

all I need to know is what relay would work to switch the leds on, cause the alarm can send a 200ma voltage and be used to switch on a relay that will cause the led's to come on, any one know?

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

A standard 30A bosch relay will work.

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Kevin Pierson

thanks man

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

how would I wire it to work, have a 12volt source go in one end, a ground for another pin, and then the aux line to one of them? is that correct, then when the aux line sends a charge it will allow the 12 volt source to give the led's electricity?

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

ok so I found that relay, if i get this Link will that be the right connector to hook to it? also I want to do like 50 led's on the drivers side, and 50 and the passenger side, how would you wire that to make sure eash blue led gets the correct 3.3 volts? should I do 3 with a resistor, or is there a way to not use resistors and just wire them in 12v series, and then hook the series together parallel? and then for the relay, there are 5 connections, im guessing that the plugs will be, 1 for 12v in, 12v out, the alarm input voltage, alarm output voltage going to ground? whats the middle prong for? any help would be awesome!!

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

ok, I learned how relays work, is this the relay required for my car, which says it needs a #775 part? HERE IS LINk, is this the same relay that will work with my leds, this one does not pass a current when no charge from alarm module is off, and when the alarm gives a charge then the relay allows the leds current? I coulnd't figure out what the difference between this one LINK HERE #2 is and the first link, is it just the allowed amperage? Thanks, if these questions are answered then I think I know how to do all the things now, just a matter of how to wire the LED's too

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

You want 100 3.3V 20mA LEDs.

That's 6.6W = about 0.5A at 12V.
So first guesstimate - a 30A relay should handle it. In fact, it might handle 60 such installations.

How many in series?
3 x 3.3V = 9.9V
4 x 3.3V = 13.2V

Some would just use 4 in series and no resistor.
If max car voltage is 14.4V, that's 3.6V which is probably within LED tolerance.
And at 12.4V (a typical non-charging real voltage?), that's 3.1V per LED.

Others prefer the resistor.....
So drop 3V @ 20mA = 150 Ohms @0.6W (R=V/I & P=VI or IxI/R).
So 96x 3.3V 20mA LEDs and 32x 150 Ohm 1/4 or 1/2 Watt resistors connected 3 LEDs & 1 resistor per string.

Each seat is 16 stings @ 20mA each = 0.32A per seat or 0.64 for both.
Let's say 1A total current. (So not ~12W total.)


You might want to double check the above and check against LED specs and tolerances - you might decide in a 180 Ohm resistor instead.....

thanks man, I am trying to figure out what relays will work for my car, I put a few links, my car says it needs either the 775 or 778 relays, will the ones from the link work?

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

I made up this diagram, will this work correctly, is there anything that I need to change?

, if that doesnt work here is another link to it Picture
Please let me know, if that works then I am all set pretty much for that part

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

Yep - that looks ok.

Include a quenching diode across the relay's coil/solenoid (85, 86) to prevent coil-generated spikes - hence protecting the alarm "input #3". Also known as spike suppression diode etc - it's just a "reverse biased" diode - say an IN4004 (400V 1A) diode or similar. (See info elsewhere - browse the excellent tuts here at 12volt.)

I'm assuming input #3 can be used as an output.
But the key issue is if it can only source or since 200mA.
Hence your relay's coil must use under 200mA.
Some relays state coil resistance but not current. Remember that V=IR so R=V/I, so 12V/200mA = 60 Ohm, or (say) 14.4V/200mA = 72 Ohm. (Normal ratings would be at 13.8V hence 13.8/0.2 = 69 Ohm.)

In other words, your relay's coil should have a resistance of at least 72 Ohm. (Higher resistance means lower current, so <200mA means >~70Ohms.)
Most common automotive relays are at least that should you should be ok. (I use JIDEC relays and they are ~68 Ohm or higher.)
Other common relays (for electronic circuits) are usually 160-450 Ohms.


So no problems - watch that coil current/resistance (ie, > ~70Ohm, or 12V at under 200mA).
For the relay contact ratig, you are only using about 1 Amp.
But 15A or 30A are the common and hence cheapest suitable relays.
A mere SPST (on-off) will do, but an SPDT (chanegover contacts) is fine (just don't use 87a).


The rest below is probably incidental....
The only other little bitty tiny incidental thing.....

Does you diagram mean your are doing 4 LEDs without resistor per string? In that case I should point out the possibility of thermal runaway, but that is probably not a problem anyhow and it will only destroy the string it is in if it does occur.
I get the impression that most "clever" people use (say) 4 LEDs in series without series resistors because it just ain't worth the hassle of the resistors, and it's 20% less soldering or strings etc, and they are prepared to replace the string(s) should problems ever occur.
[I have 2 links somewhere - one points out that strings tend to be self stabilising because the other LEDs limit the current etc; the other shows how people will argue despite them having their electrical basics very wrong (Ohm's Law), and they never do a simple example/analysis of a string of LEDs (despite linking to complex data and info themselves).]

If using resistors, I should still point out thermal runaway, and that for high-voltage strings (where the supply voltage is much higher than the series LEDs), only a constant-current element per string will prevent it, though a resistor does provide some stabilisation....

would I be safer to use resistors to make sure the LED's do not get an over voltage, I would prefer them to last a long time then having to replace them all the time.

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

what resistor would you hook to each 4 led chain to keep it from damaging them?

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

Probably no resistor for 4 LEDs.

But what is the max voltage the string could see?
And what is the max voltage or rather, current - each LED can tolerate?   


You may have to decide yourself on the risk. I get the impression thermal runaway is generally not a problem for low voltage situations - ie, 15V etc.

For a short overview of LED thermal runaway, see What's the deal with LEDs wired in series or parallel? What about "current hogging" and "thermal runaway"?.

For more detail, see Avoiding thermal runaway when driving multiple LED strings

To see how some beg to differ and then beg release - aka hang themselves wrt LED resistor & thermal runaway arguments - see mp3car's Changing cold cathode backlighting to LEDs (+auto brightness control)
The best thing in the latter is the LED spec in post #59 - ie, the "nice LED" pdf link - that gives some nice Vf and current characteristics.

I think i will do what I did in my setup picture, 4 per series, and then parallel the series ones together, but I will add a 33ohm resistor just to help a bit if the voltage on the battery starts to go above 13v, do I put the resistors on the negative side of each series string, or the positive side going into each set of series?

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

Hey, I was wondering, could I use this switch on the led's Switch Link, I want to hook up the door on switch to the led's and have this switch between them. So it would be a door switch and a auxilary output to the relay, same input on relay, and diodes on each auxilary and door wire to keep current from flowing back, and then this switch would go between the door and relay wires, and another switch between aux output and relay wires, that way I can make it so the door do not turn on the led's and the remote could make it so I could turn off the auxialy output from turning on led's?

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

So you will use 2 20W or one 40W 33Ohm resistor?
I suspect that has more effect as a heater than helping limit the voltage!

[quick calcs- 39 leds in 9 strings of 20mA each = 180mA x 33R = 5.94 = 6 volt drop across the resistor, or 12V if for all 18 strings.... if 6V, 15v-6v = 9v/4 = 2.25V per LED
if it were 33R per 20mA string = .66V across resistor => string V (presumably) is 4x3.3+.66 = 13.86V. if 30mA = 3.5V (from mp3LinkData) then Vs=4x3.5+.03x33 = 15V, so 15V via 33 Ohms in each string is LED current of 30mA; voltage increases 8%, resistor-V increases 33% as does LED-current, led-V increases 6%.]
Yeah - need to compare to non-R version....

Resistors like switches can go anywhere - it doesn't matter.
IE - you can switch +ve or ground.
Within a string, a resistor can go anywhere - ie, -R-L1-L2-L3- or -L1-R-L2-L3- or L3-L1-L2-L4-R-

If the alarm like the door-switch is grounding, you might be able to join them together to ground the relay solenoid (#85) with the other end {#86} to +12V. But then both are grounded together - ie, the alarm turns on door lights etc, so it needs some thought. What else is connected t the door switch etc?

A switch between #86 & +12V can be master of switch.
Another ground switch connected to #85 can be a manual on.
There are lots of ways depending on how things are wires etc.

I am going to do series of 4, each led is 3.1 volts, so 13 volt car battery - 3.1*4 = .6 voltage left, then .6/.02, because of a 20ma draw, so it ends up 30ohms, so I got 33 ohm resistors, and will do sereis of 4 with a resistor on the positive side of each set, and will do a total of 72 leds with 18 parallel groups

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

A 12V battery is rarely 13v.
A normal range is from flat 11.6 to full 12.6 or 12.7.

If higher, it's usually due to surface charge that they have after charging - typically up to about 13.6V.

And not that your engine will be running whilst disarming the alarm etc, but the battery is usually from 13.8V to 14.4V - ie, the alternator voltage, where 14.4 is the typical maximum long-term battey charging voltage.   
Some vehicles may charge at up to 16V just after cranking.
Some batteries (Optima, Odyssey) may allow above 15V.

I'm pointing this out in case you are not aware of normal voltage ranges.

I would expect that a full battery that hasn't been charged for a while etc - eg, a rested vehicle with an alarm system after a few hours - would have a battery voltage of about 12.6V. (3x4.1 = 12.4V)

Not that the resistor value will make much difference - it is not that critical - use 27 or 33 Ohm (not 30) - it is 0.02 volt difference per Ohm (20mA x 1R = 20mV).

I only did that as a voltage because it was a bit high, so to make sure the leds do not get overpowered, what is the lowest voltage a led can work without the power going out? cause if you get voltage drops from lets say a kicker 1500.1 amp pulling easily 100 amps, would that cause the leds to go out?

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

dereileak wrote:

---

what is the lowest voltage a led can work without the power going out?

---

P presume you mean the LEDs extinguishing?

That's a bit tricky....

Using the specs from that mp3car link, the LW P4SG LED has a Vf (voltage) range of 2.9-3.7V with a nominal voltage of (about) 3.2V.
(And those voltages may be pulses too - but if they light up when pulsed, they will definitely light up with DC.)

LEDs still operate with very low current - eg 1mA and lower.
As someone wrote recently, a LED with nominal 150 Ohm resistor still glowed dimly with a 5 k-Ohm resistor.

(Hence why a resistor is good for stabilisation - ie, resitir voltae drops reduce with reducing current (hence keeping LEDs at a higher relative voltage) and increase at higher currents (hence reducing the LEDs relative voltage to the supply voltage.)


You need to use the specs etc.
Or use the method clever people use - suck it and see.

Run a string or few of your LEDs in various combinations and see if it matters, or what blows.
After all, even if you have the skills to used the specs, do you really trust them?? (Hey - that's my excuse and I'm sticking to it! LOL)


But the answer is that the LEDs will extinguish when their voltage drops below their threshold voltage - maybe 2.5V for a 3.3V LED etc.

Keep in mind that the model for a LED is a zenor diode with series resistance, or a battery (with ideal diode) and series resistance. But that zero or battery voltage is usually a bit above the threhold or cut-off voltage because models are usually for normal operation ranges - maybe 5-10mA or 1-10mA.

thanks for the replay man, I can't wait to get them, if I do add a switch, can I just get a 2 prong switch that stops the positive charge, or does it need a 3rd prong to ground at that point? cause I do want a switch to manually turn them off and keep them off if I need to, also what would you use to put 36 LEDs' on, I was thinking a plastic ruler and just soldering them on there, but you have any better solutions to make it super nice? its 2 things of 36 LED's

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

meant reply, not replay, aha ahhahah a

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

Just an on-off switch will do - anywhere it interrupts the current.
If you use a relay, the break its solenoid (86 or 85).
Otherwise the LED's link to gnd, or between the +12V and the LEDs.

Breaking to ground may be easier as one end is "just" as chassis/body connection. (And - just like battery isolation switches, it is far less hazardous.)


As to mounting - I'm not the one to ask - I would use fluoro tubes for that reason - unless it needed bending.
If they are to be under the seat, I am curious as to who would see it, and if - under those circumstances - they'd even care. (Show judges excepeted - they'd always care!)

I am doing it just for my own personal coolness, ha ha, I am going to mount them under the feet area of the driver (me) and the passenger, it will look cool, and the relay will allow me to turn it on with my alarm remote. So as for the switch, I can put it in the ground wire, and if it interrupts ground them it will stop the circuit? My only worry is this, and I do not know if I am right, if I break the curcuit and the relay is sending 12v to the leds, will that cause any issues, or does it stop all electricity going to the leds and nothing will burn up, like wires burning up, also I found a multimeter on ebay, what do you think of it, I need it for the car alarm remote start install link to DMM, is that one junk, or is it half way decent, I will probably only use it for the install, but I want one that will last a few years if I do any other electrical work :P, btw you have been a great help!!!!

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

Why is it eGay links rarely work??? (LOL!)

Yep - that DMM is ok, but you can get cheaper (at least here in Oz).

I have a similar DMM but that includes a backlight for the display - very handy when broken down in shark infested deserts at night.
The hold is useful at some VERY rare times (for me). But it is probably more of a pain when I DO NOT realise it's on... (Why tf is it displaying that funny reading - low batteries? faulty leads? .... 5 minutes later "damned bluddy HOLD button. Again!" And that's ME - a clever dork with lots of experience!!)

May shops now have cheap $10 DMMs with much the same features (except the Hold, and backlighting).
They typically seem to be yellow, and unlike that eGay unit....
- include battery(s)
- include transistor testing (gains etc) (which I am yet to use - despite building a tranny tester eons ago).
I have several of those as spares and presents. I've seen them down to $3 each (without leads).


Apart from the usual features, the main one to look out for is the "continuity tester with buzzer" (audible continuity) - the "sound waves" as shown on your linked DMM on the RHS above "200" (Ohms) (at about the 2:30 position).
That might be trivial, but one of my cheap $10 DMMs has it as well as my (then $26, now ~$20) favorite backlit DMM with its bluddy $%#!&&*^! Hold button, and it comes in so handy when checking cables (don't look up, just keep looking at pins and listen).    
But I wouldn't pay much extra for it.

BTW - try to get spare fuses. They are usually 250mA M205 (20x5mm) - but check. Eventually you will connect wrong and blow its fuse.
And NEVER connect an ammeter (current range) ACROSS anything (specially caps & batteries!) - always "insert" it in series with the load.
And NEVER take resistance measurements on a powered or charged circuit - the DMM's battery supplies power to test resistance - ot won't like getting power from outside. That includes continuity and diode testing.


And DON'T under-estimate test lights. Whilst perhaps of limited value for testing forward voltage drops, current etc, they can be much less complicated and even safer to use than a DMM.
And they can do some neat test things.... (Yes Howie!)
And they are cheap.
And you can have a buzzer in parallel....


And opening an electric circuit isn't like stopping water - there is no hammering effect - the electric current merely stops.
[At least for your circuit - it's different if we talk about inductive circuits like ignition coils (they're shocking!), or opening a circuit with several thousand DC amps (they explode!), but even opening a relay or switch to a 3,000 amplifier is no problem. And your circuit is what watts - 10W?]

Electricity must travel in a loop - ie, out battery+ through switch and circuit back to battery- & through the battery.
To stop a "circuit", just break that loop anywhere.
But make sure there are no bypasses or leaks.
EG - if you switch open one of your 3 or 4 LED strings, it will extinguish, but all the other strings will still be lit.
If you break the 12V to seat#1 but not seat#2, seat#2 will still be lit.
If you break the supply from battery+, none will light.
If you bypass that battery+ break with a resistor (aka, a "leak"), the the LEDs will get current & voltage, and maybe enough to light them (if the resistor is not too big, and assuming the relay or switch is closed).


I think you should have a search for some basic electric tuts.
They may have been too "urrghh!" before, But I reckon now, you will click the odd "arrr fudge - now I get it" etc.

Here on 12volt are some EXCELLENT tuts (tutorials) - eg - see "Basics" way up top-left under the12volt.com banner.

www.allaboutcircuits.com/ is another goodie - see Volume 1 - DC. (I must tell them that their "power factor" is wrong - but that's AC crap....)

And try to skim a lot and just read the easy bits rather than trying to understand each bit.
Do the easy, fun, or rewarding stuff first. The hard stuff eventually makes sense "without even trying".

The best way to learn is often tactical - learn only what you need to solve your problem. (Be aware of other vague things mentioned, but review them later.)
The solve your problem - ie, design or implement.
But then review (whether before building or after, or after it blows up) and the other vague things may then make sense, or tempt you....

Electrics & electronics is no different to most other disciplines, you need to understand everything before understanding anything....
Or am I thinking of microprocessors and programming LOL!
(Reminds me of "I want everything louder than everything else".)
But once you get an edge somewhere, you just keep expanding.
And making all the "common sense" mistakes we all do.
(Remember - common sense is what you have until you know better - and that's the new common sense, until next time!)


So forgive the ramble, but that's what you get when you say silly things like "you have been a great help". LOL! (Thanks for that!).

But some of your questions & answers are VERY basic things.
Others are not - like LED voltages & effects. (You may have seen in one of the links I posted just how wrong an "experts" common sense can be! It was easily solved, but the usual ego saving techniques prevented any getting of wisdom. And that merely involved LEDs! Wait till you do batteries!)

The point is, after this you too may well be an expert in how to set up these LEDs - and know more than me about it.

WOW MAN, HOLY COW, GREAT INFO, you know your stuff defiantly, man thanks for all they help, you are an expert at this stuff!! I will defiantly check out those tuts, an place online where I can get a Multimeter cheaper? or like a store that I would have here?


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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

I would highly recomend a Craftsman meter.  Don't get the cheapest one they sell, but there is one around $25 that does auto ranging DC and frequency.  Frequency is a great tool for finding tach wires with remote starts.

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Kevin Pierson

where can I get that one at, lowes? walmart?

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed

Craftsman is available at Sears and possibly Kmart.

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Kevin Pierson

Excellent suggestion (not that I know that particular unit).

But auto-ranging is great - especially for first-timers. (And often professionals too!)
And it means you only need concentrate on not mis-connecting (ie, OHM-ing powered circuits, Amp-ing across power sources).

And frequency is real handy.

Thanks KP!

I just picked up a cheap GB one, it does AC-volts, DV-volts, and Resistance, that is all it does, but I believe that is enough to install a car alarm and remote start? cost 12 bucks, I can return it if I need, not opened yet, but if it does the job I will just use it, I already spend a lot of money for all they stuff I need, 100 dollars in parts, bought some extra stuff, but still adds up quick, you think that one will work fine?

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Viper 5902 - Ordered
Kicker Dual CVX 15's - Installed
Kicker ZX 1500.1 Amp - Installed