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In my car boot there is a cigarette style power socket, I have a one of these:

https://www.amazon.co.uk/gp/product/B077D71HXY/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

I also have an Arduino Uno R3:

https://en.wikipedia.org/wiki/Arduino_Uno

A CAN Crocodile:

https://www.jv-technoton.com/products/cancrocodile/

Finally a neopixel strip:

https://www.adafruit.com/product/1138?length=1

I want to power all of these from the car supply, the neopixel strip is configured in 3 rows of 62 pixels. The CAN Crocodile requires 12v.

How can I power all of this from the car's outlet and ensure that I have 5v for the Arduino, 12v for the CAN crocodile and enough current to run the Neopixel strip without causing damage to either the car or the components?

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  • \$\begingroup\$ use a separate power supply for each device ..... the usb adapter most likely requires special handshake in order to provide the higher current to a device \$\endgroup\$
    – jsotola
    Commented Oct 12, 2018 at 1:23
  • \$\begingroup\$ @jsotola, that's kind of where I started, I'm not an electronics guy, can I do this from the car supply? \$\endgroup\$
    – SPlatten
    Commented Oct 12, 2018 at 1:24
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    \$\begingroup\$ IME usb chargers only require special hanshakes to provide increaed voltage. the full curren wioll probably be availabe from the start. \$\endgroup\$
    – Jasen Слава Україні
    Commented Oct 12, 2018 at 2:59

2 Answers 2

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The led strips are rated at 3.5 Amps at 5V per meter, 60 leds per meter. You have 186 leds, so at full white you are pulling 10.85 Amps, or 54.25 Watts. Your usb adapter is only rated for 2.4 Amps at 5V. Even if you use the QC 3.0 voltages, this is not sufficient for the led strip. You need a higher amperage 12v to 5v adapter. The can croc needs 12V 300 ma at most so it's just a minor draw compared to the 5V adapter needed, and can use a simple 12V car outlet splitter if you need to. Together, it's a little over half of what a 12V car outlet can supply, 120W, typically fused at 12V, 10 Amps.

A quick look online shows that 60W 12V to 5V car adapters are not common. If you can ensure you never go full white 100% brightness, you could get away with a 50W, 12V to 5V 10A max supply. Those are more common.

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  • \$\begingroup\$ The strip will never go all LED's full intensity white, I have ensure that the worse case is two rows full intensity white and one row red, that's the worst case. Is there a solution that I can implement or am I looking at a custom design? \$\endgroup\$
    – SPlatten
    Commented Oct 12, 2018 at 5:30
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    \$\begingroup\$ 3.5 Full White+ 3.5 Full White+ 1.7 Red+ 0.36 extra 6 leds+ 0.3 Arduino) * 5= 49.5 W. Just enough for a 50W 12V to 5V adapter like dx.com/p/… (No personal experience with this specific one) \$\endgroup\$
    – Passerby
    Commented Oct 12, 2018 at 6:13
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I would modify the charger,soldering wires to the power (+5 and ground) pins of the two USB sockets and to the input terminals and run those wired to the neopixels. arduino, and the crocodile. I'n use some sort of plugs to allow de-tangling

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