user49962: I have purchased a cigarette adapter that gives me 2 USB ports, however this gives me 5v and up to 2.4A.
Thats ok for powering the Arduino Uno, I need 12/24v to power the CAN crocodile.
I also want to drive quite a lot of NeoPixels.
How can I do this?  

user27653: A reasonable estimate for current consumption of 5V NeoPixels is 60mA per pixel. For 186 pixels, that means about 11.16A at 5V; well over the 2.4A of the adapter being used for your other components.
There exist modules called "DC-to-DC Buck Converters", which can step down the 12-14V of your automobile to pretty much any voltage under the input voltage. To be safe, look for a buck converter of at least a 75W rating, and which meets your criteria for input and output range (minimum of 12V input, could be rated higher; output range inclusive of 5V.)
Be sure that the Ground connections for the NeoPixel power supply and the other supply are shared/connected, but don't share the +5V line between supplies.

49962: <p>I have purchased a cigarette adapter that gives me 2 USB ports, however this gives me 5v and up to 2.4A.</p>

<p>Thats ok for powering the Arduino Uno, I need 12/24v to power the CAN crocodile.</p>

<p>I also want to drive quite a lot of NeoPixels.</p>

<p>How can I do this?  </p>
 27653: <p>A reasonable estimate for current consumption of 5V NeoPixels is 60mA per pixel. For 186 pixels, that means about 11.16A at 5V; well over the 2.4A of the adapter being used for your other components.</p>

<p>There exist modules called "DC-to-DC Buck Converters", which can step down the 12-14V of your automobile to pretty much any voltage under the input voltage. To be safe, look for a buck converter of at least a 75W rating, and which meets your criteria for input and output range (minimum of 12V input, could be rated higher; output range inclusive of 5V.)</p>

<p>Be sure that the Ground connections for the NeoPixel power supply and the other supply are shared/connected, but don't share the +5V line between supplies.</p>
