Load resistor for 286 bulb type

Ardennes1944

Bit of a specialist question here that some genius must know. i need to fit load resistors onto the wiring for my angel eyes so i can change the 16 standard 286 bulbs for smd ones. when i tried this without resistors on a dummy run when i was putting in the headlights first the car was fine for a few minutes and then went bananas with the boot unlocking itself and everything lighting up on the dash etc. :pac:

so could anyone give a rough idea of what size load resistors id need for the switchover and if i need 2 (one for main supply wire on each side) or 16 for every wire for each bulb?

car is an astra h.


thank you

langdang

hmmm, sounds more like an earth fault or a short or something rather than the car getting in a bit of a huff because your "parking lights" aren't using enough juice.

To answer your original question
You'd only need 2 load resistors - one for each side between the main supply into the unit and ground.
The lights are parralleled after that point within the unit. I'd imagine anyway.

This is assuming that the individual 286 LEDs are suitable themselves for 12V

Ardennes1944

its the canbus system telling me there was a bulb blown originally when i put the leds in first. all went normal once i took them out and from reading online it seems the odd few people get away without using the resistors but most have to to fool the car. noone seems to be able to say what resistance one they got

langdang

The boot unlocking concerns me! I doubt a blown bulb would cause that, so I suspect there is more to this than lack of current in a parking light circuit.

Did "everything" light up on the dash, or just a blown bulb indication?

Ardennes1944

it is definitely just the canbus system i would hope. i have smds installed everywhere in the car nearly and no problems. my canbus hids work perfectly. once i disconnected the battery for a while all the problems went away. this is about 6months ago now and everything has been fine since. its just its a bumper off job so id like to have all the correct materials when doing it

sorry not the dash the radio screen shall we say. it just said check front right headlight, front right fog light, front left headlight, front left parking light etc

langdang

The "angel eyes" (or angle eyes to use donedeal shpake) turn on when you turn your light switch to "parking lights / sidelights" yeah?

So that's what the canbus is expecting to "see" - get a load resistor (aka warning cancellor) to suit a sidelight circuit. eg http://www.ebay.ie/itm/2x-LED-CANBUS-NO-ERROR-LOAD-RESISTOR-4w-5w-6w-W5W-T10-T4W-BA9S-H6W-BAX9S-FESTOON-/300682920786?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4602194352#ht_2541wt_982


Disclaimer - I've never done this, I'm just applying a bit of general electrical/electronics knowledge.

Ardennes1944

so i need it for a sidelight circuit, makes sense. i didnt know if it would be ok for the angel eyes. do those resistor packs literally just clip on?

thanks langdang

langdang

Well, give somebody else a chance to find an issue with what I've suggested before you rush off to eBay!

Yeah, it goes in parallel with the LED circuit, so it clips between the 12V of the sidelight wire and the negative wire for the sidelight.

The boot unlocking is still making me think that there is something else going on...

Ardennes1944

i will :pac: it makes sense though, it was originally a sidelight circuit and if i only need to use two resistors then i will be applying it to the original sidelight circuit before the many wires of the angel eyes start

im gonna put the boot unlocking down the the car having a sh!t fit

langdang

Ardennes1944 wrote: »

im gonna put the boot unlocking down the the car having a sh!t fit

When I saw your other thread I was considering washing my hands altogether of your electrical gremlins! You'd swear it was french!

Ardennes1944

well this problem is due to me dicking about with leds. and the other one is something the auto sparks did so nothing the car did really. it was fine till i tried to improve it

germanhelp

Well assuming that the 16 x 286 bulbs are in parallel across the circuit and what I've googled is correct, each bulb draws 1.2W each. Therefore the entire circuit is drawing 19.2W of power.


At 12V that's means (Power =Current x Voltage) there's a current draw (I) of I = 19.2/12 = 1.6A

Now P=I*I*R, so R = 19.2 / (1.6 * 1.6) = 7.2 Ohms resistence presented across the circuit.

What's the load of the SMT LEDs? Googling seems to suggest 0.5W, so 16 x 0.5W is 8W draw. I need to make up another 11.2W of a draw, in simple terms this is is a resistor that will shunt 11.2W of additional power off the circuit. To do this we need to dump 11.2W of power or 11.2=12*I, I=0.933A of current, so with R=V/I, R=12.85Ohms

Now these loads are in parallel, so we have to calc for this

Basically 1/Rtotal = 1/R1 + 1/R2. We know the total resistence for the circuit needs to be 7.2 Ohms and the LEDs are presenting 18Ohms, so R1 needs to be:

1/R1 = 1/Rtotal - 1/R2

1/R1 = 1/7.2 - 1/18

R1 = 12 Ohms.

So get a resistance that presents 12 Ohms resistance and can sink 11.2W

germanhelp

Actually looking at the ebay link presented, these resistors are for side light bulbs and only shut upto 6W. You're looking for double this, so if these are rated this low you'll blow them

Hal1

I've seen canbus error free led bulbs on ebay, I think they have the resistors fitted to them. Btw CREE are the best led bulbs imo. There a bit more but are very good quality.

Ardennes1944

At Hal, I have canbus free smds everywhere else in the car but you can't get them for 286
I have 3 Cree torches and they are fantastic

Thank you for the above calculations Germanhelp it was exactly what I was looking for! I'll scour eBay for suitable resistors. Much appreciated.
As another question, what if I wired 2 of the linked resistors for each side? I know the ohms might still be wrong

langdang

http://en.wikipedia.org/wiki/KISS_principle

A parking light circuit is typically a 5W (per side) circuit.
The Canbus should be happy with 5W ish each side.
The resistors I linked to are for compensating sidelight circuits.

They, or a similar product from another seller, will work.

germanhelp

The CAN bus is just a way of communicating, it doesn't set current requirements par se.

In the OPs instance he's changing the existing bulbs that present a load of 19.2W, I don't think these are powered off the sidelight circuit. Placing 19.2W on the sidelight bulb circuit will blow the fuse. That's why I don't think the posted ebay current sinks will help

I assume the OP(as he is in Detriot) is pulling from the DRLs that would be fitted to the car. Could be wrong.

jayok

I had posted a reply here but on phone and done something stupid.

Basically if you want to place the two in parallel you need to make sure that the resistance remains the same to make sure no fault is reported. This needs to be checked

Ardennes1944

germanhelp wrote: »

The CAN bus is just a way of communicating, it doesn't set current requirements par se.

In the OPs instance he's changing the existing bulbs that present a load of 19.2W, I don't think these are powered off the sidelight circuit. Placing 19.2W on the sidelight bulb circuit will blow the fuse. That's why I don't think the posted ebay current sinks will help

I assume the OP(as he is in Detriot) is pulling from the DRLs that would be fitted to the car. Could be wrong.

I'm in cork and don't have drls as standard, just using the original sidelight wiring as langdang said

ZENER

Given that the nominal voltage in a car is closer to 13.5 V with the engine running and the that the resistor is conducting over 1 Amp then a resistor with a rating of 15W plus would be more desirable to prevent failure and to ensure efficient heat dissipation.

Something like this would be suitable.

Ken

galwaytt

.....well, I've heard of people in both motorcycle and commercial worlds leaving one bulb in the circuit, tucked out of sight, flashing away (under the seat/bonnet etc), just to fool the things.