Author Topic: Solid State Relay to power anything on car Non-Stock and avoid blow ControlUnits  (Read 1128 times)

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Offline dssence

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Hi guys , I have a Toyota 86 FT (same as Scion or Subaru BRZ) so to be short I wanted to add a led strip to my position lights (ones which light up when you turn on backlight on instrument panel)  or a T10 led bulb to replace the ugly stock original bulb.  I know you can easily screw up "Body System Integrated" units when diminishing the amperage going through that circuit, as most circuits are designed for resistive loads.
     So,if I take out the led bulb for instance which is a T10 format 5watts , and replace it with a led strip which draws 600mah I could easily blow up the driver of that circuit on my car.
So take 2 scenarios

-First Scenario  (Adding led strips for position lights to each headlight, removing the original 5 Watts T10 bulbs )   

In this scenario a friend of mine came up with a solution to use a solid state relay opto coupled  (IXYS part number LC717) to avoid damagin the driver.  This is in theory how it would be connected. But I have many doubts

As you see the output + of the SSR to switch both ledstrips go to the cars battery, and the Control line of the solid state relay goes to one of the positive lines of the position light harness, so when I turn on the knob on the instruments panel it lights up
   Now these are all my doubts

1) We are lighting up an IR led diode with the positive line form the position lights which in turn is coming from a driver. I know it's not the same as plugging a resitive load there. But we're lighting up a led diode. So this could, well blow/damage the driver?

2) Shouldn't we be emulating the original resistive load instead? rather than lighting up a Solid state relay IR led. By emulating the original load I mean, if the original position light was a 5watts bulb and if I measure it with a dmm and it's filament measure 150ohms, shouldn't I replace a 5watts resistor 150ohms in series with the led strip I want to place there?. All this instead of using a solid state relay?

- Second Scenario (replacing the original 5 watts incandescent bulbs with LED bulbs T10 same wattage)

Say I want to replace the original incandescent bulbs 5watts with led bulbs T10 same wattage , would this damage the Control unit. ? My friend said it could. Cause the circuit it's not designed to handle this kind of load which is not resistive.

This is the kind of bulb I'm talking about .

Should I have to use this load resistor instead? Or precisely on which case should I add a load resistor like this one

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