Dash cam power supply/timer wiring?

[RavenManiac]

I was doing some research today for my upcoming dash cam timer project and I discovered, much to my surprise, that thicker gauge wire actually has less resistance than thinner wire. For some reason I thought the opposite was true since the electricity has to travel through more wire.

Now that I've been properly enlightened, is there any reason I shouldn't use 16-gauge wire versus 18-20, as long as I have a low amperage fuse that will protect the dash cam power circuit? BTW, the add-a-fuse kits usually come with 16-gauge wire, which I'll need to butt connect into, which is why I'm considering 16-gauge for the entire setup. And, as an added bonus, thicker wire usually has stronger sheathing.

[Update]
I also discovered that red means 12V switched and yellow means 12V constant–well at least for stereos. So... although I wasted an entire weekend preparing for this project, I did learn a little something.

 

[niko]

I would not use direct stereo-related constant or ground wires, - in some cars they might give interference if you connect additional accessories., of course it's all depends on car make / model and how good is ground wire "grounded".

 

[RavenManiac]

I would not use direct stereo-related constant or ground wires, - in some cars they might give interference if you connect additional accessories., of course it's all depends on car make / model and how good is ground wire "grounded".

No, I wasn't going to tie into the stereo wiring. I was just illustrating that there seems to be a color coding system for some types of wiring, such as yellow for 12+ constant, red for 12+ switched, and black for ground. With this knowledge I can use colored wires that are appropriate for my timer project.

 

[erkme73]

HA! Now you know why my actual wiring was opposite of the 'crude' drawing I made for you. I thought (as I was building it) that red was constant and yellow was switched - when it turns out to be just the reverse.

As to your question about resistance, think about it as volume (or flow) of water through a pipe. Pushing it through a tiny drinking straw creates a significant reduction in flow, while a fat pipe has virtually no resistance.

Cable resistance usually comes into play with lower voltage and higher current equipment. Since these cameras require very little current, even a tiny 20ga cable would be adequate. However, what will booger you up is the low voltage. Even with minimal load on the far end, if your starting voltage is very low (i.e. 5V), the the voltage drop may leave you with a end-of-line voltage that is lower than the minimum for the camera.

If the camera needs at least 4.95V to operate reliably, and despite pushing 5.15 volts at the supply side, you're only able to get 4.8V to the camera, you may get some real gremlins. It might appear to work, until the camera gets hot, or the battery runs low, or ...

Basically, if you run 18ga no more than 15' you should be fine. If you need to go further, use 16ga.

 

[RavenManiac]

Gotcha. Yeah, I decided to go with 16-gauge throughout ONLY because it matches the wire used on the fuse taps AND I could buy it by the foot. Nothing should be longer than 2' max.

 

[Nigel]

Gotcha. Yeah, I decided to go with 16-gauge throughout ONLY because it matches the wire used on the fuse taps AND I could buy it by the foot. Nothing should be longer than 2' max.

Maybe someday the USA will convert to using international units like everyone else and we will all be able to understand you, not even the google calculator can manage"16 gauge=?mm2"! And what is the meaning of "Nothing should be longer than 2' max" - why are you measuring length in minutes?

Just thought I would point out why you aren't getting much response to this thread

 

[jokiin]

not rocket science

 

[niko]

Maybe someday the USA will convert to using international units like everyone else and we will all be able to understand you,

Start is already made many years ago with 2.0 ltr Coca-Cola on USA market.

 

[RavenManiac]

Well, I lived in Canada for two years when I was in grade school. I didn't do very well with spelling, but I did pick up the metric system—which makes a whole lot more sense to me. I think the US tried to convert back in the 70's but it never took hold. I think it's because us Americans need to feel special. LOL

Well, us and the Aussies.

 

[jokiin]

We're all metric, we're not so ignorant that we can't understand your units of measure though

 

[RavenManiac]

Really, I didn't know Australia converted. I guess I'm behind on that. Too busy keeping my Imperial tool box straight.

Just remember though, we are both likely descendants of the British so go easy on Nigel. And we're allies. With all the crap that's going on, we'll probably need that allegiance sometime within the next few years.

 

[jokiin]

We went metric many years ago

 

[niko]

I am OK to convert on the go straight from my head most common imperial values. The only thing I still struggling is converting mm into inches.

 

[Nigel]

I am OK to convert on the go straight from my head most common imperial values. The only thing I still struggling is converting mm into inches.

But it gets complicated with things like gallons because the USA has a different amount of liquid in their version of the gallon which then means that miles per gallon is a different value in the USA, and then Oz has it's own definition of the pint, defined using litres!

With the USA being the only country left to use non-metric for almost everything there is not much reason for the rest of the world to fully learn what is a fairly complex system.