how's this electricity stuff work, anyway?

What Rd

What Rd

NAXJA Forum User
Location
Athens, IL
I'm in the process of wiring and plumbing a QuickAir II compressor in the cargo area of my rig to run the ARBs and fill tires. My question has to do with the wiring to get power alllll the way back there. I got some good quality 8 gauge cable with lots of fine copper strands. The problem I'm having is figuring out what sort of connectors to use to wire in the relay, etc. By using a small spade connector am I not creating a bottleneck or weak link such that the run of cable will only be able to flow as many amps as can squeeze past that spade? How do I get around this? Where can I get some sort of connector that will freely flow the load and still hook up to a standard 40 amp relay?
(if you can't already tell, I'm an electrical idiot, so be gentle and be simple!)
 
As long as you use the yellow color coded spade connectors you should be alright. The little bit of drop that you'd get from it would be nothing compared to the voltage drop that you'd get if you tried to do that run with 12 or 16 guage wire. Don't forget to make sure that all your grounds are good too, compressor to body, body to battery.
 
When using very short lengths, such as a connector, the thickness, or gage, isn't nearly as important. It's the longer runs, such as the wiring, where the gage is more important. You're on the right path by using the 8 ga. wire. Make sure you are using a large enough relay to switch the power to the compressor.
 
You might want to consider soldering the connections as well as crimp for a little extra protection (solid connection and conductivity). Otherwise stay away from the automotive parts stores and visit an electrical supply shop for good quality connectors and advise.
 
I suppose it'd be good for me to study up on some basic electrical theory. I just never learned much of that along the way.
For instance, I have a good 40 amp relay, so that should be no problem. But if I run that nice 8 gauge cable into a little spade connector, there's a bottleneck. Does electricity speed up to pass the same quantity through a smaller passage in the same amount of time, the way water or air do? An electrical venturi effect? Would this be why a too-small point such as a spade connector can fail from heat or cause a short or fire? The electrons moving through at a faster rate?

Soldering sounds like a good idea (though I'm not set up for that except for my plumbing tools and my guess is those wires and relays wouldn't like my torch). What does a soldering iron cost?
 
The "bottle neck" in the conductor in which you are talking does happen but in a form of heat. The yellow sleeve connectors are maxed out at #10 wire but you can remove a couple strands to make the #8 fit. This should work fine in your application.
 
electricity flows exactly like water. The smaller the wire/connection (hose) the faster the electrons have to force their way through. This can usually be seen (or felt) as heat. The friction of all those little electrons cramming their way through creates heat. You will still get a little of a bottle neck with soldering, not as bad though. Soldering irons are cheap. Usually if you are using a large enough wire (sounds like you are) and the proper sized connector there is very little heat and falure is rare. With wire and a connector that is too small, yes you will have a problem. Burned out connectors and melted insulation. I think you'll be fine with the blade connectors. This isn't a constant duty item anyway.

Neil
 
Electricity only has one speed-186,000 MPH !!
 
heat=resistant=heat=resistant=heat=resistant till the wire melts. 8ga wire in a 10ga terminal should be no trouble, fuse or breaker at the battery is a must.
 
Use a constant duty solenoid (looks like a starter solenoid but is rated for continuous duty) instead of a relay with quick connects...get some solid copper ring terminals and solder them to the wire...i'd advise that you also install a 50 amp circuit breaker between the solenoid and the battery..rig a toggle to power the solenoid coil and you are ready to go.
 
Weasel said:
go run down to your car audio joint and see what they got. I have seen connection blocks that look like they would wrok real nice.
Click to expand...
I second weasel's statement. My Bro works at a car audio place, they can figure the load sizes, wire sizes, connectors, fuses, etc.. Avoid department store installers though.
 
:clap: :clap:
Thanx a bunch, guys. I'm feeling much better about this now.

The first car audio shop I went to wasn't helpful beyond supplying me with that nice 8 ga. cable. They didn't have any connectors that would work for me and didn't seem interested in my OBA setup (can you imagine - some people's priorities!). That's when I posted.

So after work I ran by a different car audio shop and found a very cool guy with all the stuff I needed and a very helpful attitude. Between that experience and the good word here - I'm all over this project now. Thanx for the help! :worship: :worship:
 
RCP Phx said:
Electricity only has one speed-186,000 MPH !!
Click to expand...

Actually the speed of electricity is 186,300 miles per second, or the speed of light. If you think of electricity like water in a hose, when a hose kinks the water doesn’t actually speed up relative to the rest of the flow. The flow just increases in the area remaining open. The same is true for electricity. I’m sorry I used the word faster, I was just trying to keep it simple.

Neil
 
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