Can led *bulbs* be wired in parallel?

[Deeg]

I'm looking into a lighting project that will use some 12v LED bulbs like this one. I know that simple LEDs shouldn't be wired in parallel but what about the bulbs? Do they have circuitry that limit the problems?

 

[MikeMl]

Yes

 

[Deeg]

Thanks Mike! Short, sweet, and for once the answer I was hoping for (it's usually some form of "it's complicated").

 

[dr pepper]

If its the same colour and the same type yes, with 2 different colours only 1 would light up, and if they the same colour but different types or batches the brightness might not be even.

 

[MikeMl]

If its the same colour and the same type yes, with 2 different colours only 1 would light up, and if they the same colour but different types or batches the brightness might not be even.

Pepper, you missed the point that these are LED LAMPS rated for replacement of bayonet-base 1156 lamps for 12V automotive use.

 

[audioguru]

It is illegal in many countries like Canada to tamper with vehicle lighting. These LED bulbs will have different brightness, angles and colors than the original incandescent bulbs that the vehicle was certified with.

These bulbs say INDOORS USE ONLY because they are not wearherproof!

 

[MikeMl]

It is illegal in many countries like Canada to tamper with vehicle lighting. These LED bulbs will have different brightness, angles and colors than the original incandescent bulbs that the vehicle was certified with.

These bulbs say INDOORS USE ONLY because they are not wearherproof!

And why should I care about obscure Canadian vehicle regulations when I replace the 12V 1157 lamps in my Camper for inside lighting as a means of reducing the total battery draw.

 

[crutschow]

................................

These bulbs say INDOORS USE ONLY because they are not wearherproof!

Where in a vehicle is a bulb exposed to the elements? All I've seen are located behind a sealed cover.

 

[audioguru]

And why should I care about obscure Canadian vehicle regulations when I replace the 12V 1157 lamps in my Camper for inside lighting as a means of reducing the total battery draw.

The campers I have seen are plugged into 120VAC at the camper sites. Why use brake light bulbs inside a camper?

 

[MikeMl]

The campers I have seen are plugged into 120VAC at the camper sites. Why use brake light bulbs inside a camper?

The whole point of owning a Camper in the Western US is to get away from camper sites that have plug-ins. For that matter, I want to get as far away from the idiots that have the fancy Class A motor homes and run their 5KW AC generators so they can have AirConditioning, TV and Microwave Ovens, too.
Mine is wired for 12Vdc, runs on 200AH batteries. It has 10 light fixtures that originally had 1157 lamps. I replaced them with LED lamps which cut my power consumption by a factor of 5.

 

[dr pepper]

Yes Mike I missed that point entirely, thanks for pointing that out.
Theres probably a constant current circuit in the base or something.
I'dve thought you'd be able to connect up as many as you like, the only thing that might make a difference is if theres some kind of capacitor inside which would take an inrush, but you'd need a lot more than you'd find in a camper before that'd be an issue.

 

[Deeg]

Thanks all. Since I don't seem to be burning down the house with my teacup pendent lamp I'm trying again. I've got a bug to attempt to make wall sconces out of vintage* cameras, similar to what this guy did. Some of the cameras have plastic and/or cloth so I'm attempting to keep the heat down, thus the LED bulbs. For other cameras I'm looking at using 12v incandescent like these. They will all be housed in sockets like these.

If I have a mix of incandescent and LEDs how would you recommend I wire them? The simplest (I think) would be to have something like a 12v, 3-amp power supply (which I have) and wire them all in parallel. Any problems with that? I assume I don't need any resistors since they are bulbs. Could I add variable resistors so I could adjust the brightness (and heat) of the lights? Am I about to burn the house down?

* - "Vintage" sounds so much better than old or junk.

 

[dr pepper]

You'll probably need more than 3 amps for incandescent bulbs, the smallest mr16 is 20w, that takes 1 1/2 amps on its own.
If they are all 12v, led and incandescent then you can wire them in parallel.
If you check the data for the led lamps some of them are dimmable, in which case you can use an ordinary lamp dimmer, also if you use an electronic transformer then it has to be the dimmable variety too.

 

[Deeg]

In playing around with the LED lamps I've noticed that I can dim them by just lowering the voltage. Why can't I just use some resistors to lower the voltage for some of the lamps and dim them that way?

 

[MikeMl]

The resistor would have to be a "power" resistor capable of dissipating up-to several Watts, resistance value to be determined.

 

[Deeg]

Using a resister basically just wastes the power by turning it into heat, correct? So the more efficient way to dim the bulbs is with a transformer that is adjustable but that dims all of them together. Would something like this cheap power supply work? Would you recommend something better?

 

[Deeg]

I see now that the power supply is only 1 amp so that's not powerful enough. I'll have to look into it some more.

 

[ronsimpson]

In playing around with the LED lamps I've noticed that I can dim them by just lowering the voltage. Why can't I just use some resistors to lower the voltage for some of the lamps and dim them that way?

I have designed LED bulbs.
Some I designed will output the same light no matter what the voltage is. Example; from 6V to 20V the light will be with 1%. The problem with them is that the LED bulb will discharge the battery to a dangerously low level then shut off with out warning.

Other designs are built to dim at low voltage to give the used a indication of battery level.
Some are designed to shutdown at a reasonable voltage. Batteries can explode or leak if you discharge them too much.

Most bulbs have a switching power supply built in. It takes voltage in and outputs current for the LED. They do not care what is in parallel.
The inrush current is small, (capacitor is 10uf to 1uf), less inrush than a incandescent bulb.