Wiring Question

Logan X · 05-12-2020, 07:50 PM

I’m planning on installing a 12v outlet in the toolbox in the bed of my truck. I was hoping to get some feedback from those with more experience. I thank you in advance for any replies.

The 12v outlet will be used for my (automotive) Makita battery charger, which draws 2.6 amps. I ordered a 12v outlet fused for 10 amps and 16 gauge wire. The wire will be routed along the frame of the truck, in a loom, into the engine compartment. It will be about a six foot run of wire. Inside of the engine compartment the truck is already pre-wired with fused “up fitter switches” so I will connect to that.

The only issue I see is the wire I ordered is CCA, or copper clad aluminum. I didn’t really intend to order CCA, I just wasn’t paying close attention.

Will the CCA work?

Does the plan seem good or do I need to tweak some stuff?

Thanks again.

bobbecky · 05-12-2020, 08:06 PM

It should work just fine, but be careful to not be bending it too many times in the same spot while installing it. Aluminum wire is a bit more fragile than solid copper wire, but for this application, it will work. When making connections, be aware that the wire will flatten more under a screw connection and may need to be tightened again in the future.

NH_Bulldog · 05-13-2020, 03:56 AM

In addition to the above, aluminum wire is a better conductor than copper and lighter than copper (that’s why it is used for power transmission lines). However, aluminum expands and contracts more when heated and cooled than copper does. Over time this will cause connections to loosen, which could lead to arcing/heating and possibly fire. Unlikely to be a big factor in your application, but still worth thinking about.

xrated · 05-13-2020, 04:08 AM

Quote:

Originally Posted by NH_Bulldog

In addition to the above, aluminum wire is a better conductor than copper and lighter than copper (that’s why it is used for power transmission lines). However, aluminum expands and contracts more when heated and cooled than copper does. Over time this will cause connections to loosen, which could lead to arcing/heating and possibly fire. Unlikely to be a big factor in your application, but still worth thinking about.

Copper has a significantly lower specific electrical resistivity than aluminium: 100, compared to 160. This difference is highly relevant for power cables. To attribute to an aluminium conductor the same resistance as a copper conductor, the cross-sectional area of the aluminium conductor must become larger to compensate for aluminium’s higher electrical resistivity. In fact, for the same current-carrying capability, an aluminium conductor needs a 56% larger cross-sectional area than copper.

**flybouy** · 05-13-2020, 04:44 AM

xrated is correct. Aluminum wire is used in power transmission lines for weight and cost savings. Heat is not an issue as it's outside. Two important facts on your wire purchase is unknown. 1. the percent of copper to aluminum and 2. what the jacketed insulation is made from.

I'm guessing you purchased this wire because it was less expensive which may answer the 2 questions above. I would not use it on my truck even though I have good fire coverage in my insurance policy.

**sourdough** · 05-13-2020, 05:29 AM

Mike,

I may have used some aluminum electrical wiring back in the 60s or early 70s. It came out that it was a fire hazard in mobile homes and I believe that use was phased out in about 1971. I've never used it since.

I know 120 and 12vdc are 2 different things but conductivity and carrying current are the same. I believe there are still inherent drawbacks to the use of aluminum vs copper although you might get by using it. I wouldn't if I were doing it.

**JRTJH** · 05-13-2020, 05:49 AM

Here's an "uninformed opinion" based on information I can find online.

First, I don't have any knowledge of the Makita DC18SE 18V Optimum Automotive Charger. That said, the information I can find states that the input wattage is 240 watts/12VDC. That's 20 amps, not 2 amps. If it was 120VAC, it would be 2 amps input.

Wiring requirements to carry 20 amps DC power for a 10' distance (from the truck fuse panel/battery terminal to the tool box outlet) requires a minimum of 14 AWG copper wire. That would give a 10% voltage drop of about 1.2 VDC at the plug. Ideally, using 12 AWG would provide about a 0.5 VDC voltage drop over that 10' distance.

From what I can find, using 16 AWG aluminum wiring would result in almost a 3 VDC voltage drop. I don't think your 12 volt/240 watt input battery charger would be "happy" operating on 7 or 8 VDC input power for very long.

Given the problems with CCA wiring when used in "enclosed areas", I'd be reluctant to use what you have (16 AWG CCA wiring) to run a 20 amp DC circuit with an effective length of 20' (10' to the plug and 10' back to ground at the source).

Considering the truck costs $50K+ and the charger costs $120+, I'd spend the $25 to get appropriately sized copper wire if it were me....

ADDED: If it were "my truck" I'd opt to use a minimum of 12 AWG wire, install a 20 amp inline fuse near the power source connection and make sure that I used rubber grommets at EVERY place the wire goes through a metal hole.

ADQ K9 · 05-13-2020, 06:30 AM

Just wondering how an aluminum body plays in this, will you be grounding directly to the frame? I am thinking your wire run is gonna be longer than 6 feet too.
I just wired up a pair of little cube lights on my A pillars to my up fitter switches and grounded to the body using 14 gauge wire. What is interesting is that the wiring coming from the switches looks to be about 16 gauge I ended up using about 10 ft of split loom to make it look professional.

**JRTJH** · 05-13-2020, 07:00 AM

Quote:

Originally Posted by ADQ K9

Just wondering how an aluminum body plays in this, will you be grounding directly to the frame? I am thinking your wire run is gonna be longer than 6 feet too.
I just wired up a pair of little cube lights on my A pillars to my up fitter switches and grounded to the body using 14 gauge wire. What is interesting is that the wiring coming from the switches looks to be about 16 gauge I ended up using about 10 ft of split loom to make it look professional.

If I remember correctly, my upfitter switch setup has two 25 amp, one 10 amp and one 15 amp circuits. (1-2 are 25 amps, 3 is 15 and 4 is 10 amps). All of them are routed through the relay box, so the "under dash wiring" is protected from any "heavy load". In my truck, all the switches are tied to the ignition accessory side of the system, so they are all "off when the truck is off" and only work when the ignition switch is on.

Mine also has "lighter gauge wiring" for the "through the firewall connections"... I wondered about a heavy amp draw, but the largest usage on my system is 2 LED lights) 0.5 amps each) in the truck bed and the RVS rear view camera system which is 3 amps for the entire system (monitor and camera). I'm not sure I'd want to wire a "heavy amp item" to the upfitter switches. If I needed that much power, I'd wire a relay to the upfitter switch and use that relay to energize a "heavy gauge source wire" for the circuit.

**flybouy** · 05-13-2020, 07:02 AM

The aluminum body is irrelevant. If you crushed that body into a wire you would probably end up with the equivalent of a 1' cross section.

With John't calculations I recommend investigating your upfitter switches. On my truck they are varying Amp ratings from 10 amps to 30 amps. A connection to the wrong switch could damage the relay and/or blow the fuse.

Logan X · 05-13-2020, 07:24 AM

Thanks for all of the feedback. I think it mostly confirms my initial hesitation on using the CCA wire. I won’t use it and I’ll get some copper stranded wire. Edit-I think I will go with 12 gauge wire to be safe.

As far as the amp draw, it can’t be 20 amps because the plug has an 8 amp fuse. I may have been confusing the input and output numbers. The output is 2.6 amps. The input is 70 watts at 12vdc. I think that would make the amp draw 5.8 amps?

**flybouy** · 05-13-2020, 07:50 AM

On the wire issue I'd caution anyone purchasing wire online from anywhere to do you're "due diligence" and research what they are selling. Amazon, WalMart, EBay, etc. typically sell "second party seller's" products and the brand/quality may be in question.

Wire is one of those products that often is misrepresented. I've read many reviews where people have received wire that wasn't the advertised gauges, conductor material, strand count, or insulating material. I've seen the same issues with "crimp connectors" and even blade fuses. If you don't know what to look for or understand the differences I'd recommend walking into a reputable auto parts store.

Making a purchase for 1/2 the price but getting 1/4 the product is still overpaying.

**JRTJH** · 05-13-2020, 02:30 PM

Mike,

Those wattages are different than what I found online. I'd go with what you see on the data plate for the actual device. You're right, 70 watts at 12VDC is 5.8 amps. I don't know how sensitive the charger is to voltage drop, but if it's "picky about working on 10.5VDC you'll be much better off with 12 AWG stranded wire from NAPA or a "real auto parts store" (not the WalMart discount rack). If you're using an "upfitter switch" to turn it off/on, you won't need a relay setup if the switch is rated at around 10 amps or better.

Remember, anywhere the wiring goes through a hole in a metal plate, use a rubber grommet to protect the insulation.....

Logan X · 05-13-2020, 03:48 PM

Quote:

Originally Posted by JRTJH

Mike,

Those wattages are different than what I found online. I'd go with what you see on the data plate for the actual device. You're right, 70 watts at 12VDC is 5.8 amps. I don't know how sensitive the charger is to voltage drop, but if it's "picky about working on 10.5VDC you'll be much better off with 12 AWG stranded wire from NAPA or a "real auto parts store" (not the WalMart discount rack). If you're using an "upfitter switch" to turn it off/on, you won't need a relay setup if the switch is rated at around 10 amps or better.

Remember, anywhere the wiring goes through a hole in a metal plate, use a rubber grommet to protect the insulation.....

Thanks John, I’m going to go with the 12 gauge stranded wire, as you suggest, and I will use rubber grommets.

**flybouy** · 05-13-2020, 04:41 PM

Mike, do yourself another favor and when you are buying the wire get some good wireties as well. I had a bag of cheap ones a friend gave me and they fell apart after being in service a year. Don't use electrical tape to secure your wire run, it won't last.

Logan X · 05-13-2020, 05:22 PM

Quote:

Originally Posted by flybouy

Mike, do yourself another favor and when you are buying the wire get some good wireties as well. I had a bag of cheap ones a friend gave me and they fell apart after being in service a year. Don't use electrical tape to secure your wire run, it won't last.

Thanks Marshall, that is what I’m going to do.

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