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Issues with arduino power from cars accessory power fuse

Schlogdawg

Jul 23, 2017
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Hello all,
I want preface this by saying this is my first "Electronics" project so my knowledge is lcking in many areas, but with that said, the problem:
My car with randomly drop power to the arduino.

I have an arduino R3 uno as my workhorse, that is being powered by a tapped accessory fuse from my cars (subaru wrx if that matters?) fuse box. From my understanding the arduino has a voltage regulator that drops the 12v to a safe voltage for the board.

I then have two identical breaboarded circuits that take the voltage input to the turn signal (12v) and drop it to ~5v and send it as an inout to the arduino.

The code on the arduino lights up two LED strips solid when theres no turn signal input and then flashes he respective strip when the input signal goes HIGH.

After the system is up and running for about 30-45 sec the arduino will flash an orange led on the board and the LED strips will turn off. Within a few secs he board/LEDs are back up and running. I have tested this with a 9v battery as power and dont have this issue, so im assuming its either something to do with the output power of that fuse? Im not sure its that because the arduino board doesnt go fully off it keeps the green LED on throughout this process. The fuse gives power through the barrel jack voltage reg and is grounded through a screw nearby. All my grounds are routed to the ground from that screw. Any thoughts on what may be the issue? If more info is needed let me know. Thanks in advance!
 

Minder

Apr 24, 2015
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How have you dropped the turn signal 12v signal to 5v?
I would have done it with a opto isolator, (4n35 etc) if not that way at present.
Also use a decoupler Cap on the input to the regulator, or build your own 12-5v version.
M.
 

bushtech

Sep 13, 2016
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Maybe try running power straight from car battery. Arduino R3 recommended voltage 7-12V. Alternator pushes voltage higher than that when charging. Maybe arduino tripping out when alternator starts up.

Alternatively is your car battery in good shape?
 

Schlogdawg

Jul 23, 2017
16
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Jul 23, 2017
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How have you dropped the turn signal 12v signal to 5v?
I would have done it with a opto isolator, (4n35 etc) if not that way at present.
Also use a decoupler Cap on the input to the regulator, or build your own 12-5v version.
M.
I have dropped the voltage, I believe im using a 8505 voltage reg and verified the voltage is ~4.9V coming from the turn signal. Output pin has a 22k Ω resistor going to the input pin.
 

Schlogdawg

Jul 23, 2017
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Maybe try running power straight from car battery. Arduino R3 recommended voltage 7-12V. Alternator pushes voltage higher than that when charging. Maybe arduino tripping out when alternator starts up.

Alternatively is your car battery in good shape?
Ya ill have to give that a go, just to test. Ideally itd be nice to not have to pass additional wires through the engine firewall. But its a 2014, so I would assume so; no corrosion or anything like that. Ive also tried plugging it in after the car starts up. Not sure if that matters.
 

kellys_eye

Jun 25, 2010
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Have you got a heatsink on the regulator?

Sounds very much as if the device is shutting down after over-heat alarm (built-in protection).
 

Minder

Apr 24, 2015
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I have dropped the voltage, I believe im using a 8505 voltage reg and verified the voltage is ~4.9V coming from the turn signal. Output pin has a 22k Ω resistor going to the input pin.

Personally if using a micro in a noisy auto environment I would isolate as much as possible.
M.
 

Bluejets

Oct 5, 2014
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Turn signal will be full of noise, as will most of the car's power. Others have covered any fixes. In short, if you need to learn about noise filtering you could not have picked a better environment.
 

Schlogdawg

Jul 23, 2017
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Have you got a heatsink on the regulator?

Sounds very much as if the device is shutting down after over-heat alarm (built-in protection).
I do not, that will be something to try. Ive tried googling a heatsink and all i could find is what they look like, Im not sure how to attach it or anything. Could you recommend something I can read up on to figure this out? Thanks for the help!
 

Schlogdawg

Jul 23, 2017
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Turn signal will be full of noise, as will most of the car's power. Others have covered any fixes. In short, if you need to learn about noise filtering you could not have picked a better environment.
Ahh okay, ya I noticed that on the multimeter. It seems to do a somewhat good enough job for what I need, but ya sounds like a have a good project to learn with. Thanks for the info.
 

Bluejets

Oct 5, 2014
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I doubt very much that you will be able to read noise on a multimeter.
 
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