Electrical Planning and Questions

[Larry de Lobster]

I'm in the process of planning out the electrical system for my '21 Tacoma TRD Off-Road and want to do the wiring right as well as leaving room for future upgrades. However, I am very new to electrical work (I've done subwoofer installs way back when I was younger for my previous cars as well as for my friends but those were from tutorials and I know I didn't do everything correct).

Foundation:
- Single Battery (will stick with a single battery as I don't think I'll need a dual battery for the foreseeable future)
- Switch-Pros SP-9100 & PowerTrays Vertical Mount/Bracket w/ a Blue Sea Fuse Box & Bus Bar (8 switches + 6 additional fused connections should cover everything I'll ever need/want and no need for relays for everything connected to the switch-pros)

The following section is what I'm stuck on.

Currently Planned:
- 6x 20W Scene/Work Lights (I'm thinking maybe 4 on the roof rack facing the sides, 2 on the bed bars facing the rear OR 2 on the roof rack facing the sides, 4 on the bed bars with 2 facing the sides and 2 facing the rear).
- 12V Socket w/ USB wired to the bed (for fridge later on) + LED Strip Cargo Lights.

Questions:
1. Are 6 20W scene lights overkill? They'll be primarily used as camp lights and I believe I can dim the lights using the switch-pros if they are too bright but they can also serve as lights when driving off-road in the dark.
2. For the wiring harness (1 for the roof rack, 1 for the bed bars), here is the math. Please correct me if I'm wrong:
- 4 lights x 20W / 12V = 6.7A therefore 16 AWG or 14 AWG should be fine depending on the length of wire.
- 2 lights x 20W / 12v = 3.4A (will use same wire gauge since I'll be ordering 50')
3. I'm planning to connect the 2 wiring harness from question 2 to the same terminal (connection? not sure what its called) on the busbar so I can control both with the same switch. Is that okay to do? or should I connect a larger gauge wire to the busbar and split off with the 2 wires going to each location?
4. The 12V Socket w/ the USB ports are rated for 120W. The fridge I'll be purchasing is the Dometic CFX3 75DZ which is rated for 9.6A or roughly 115W (if my math is correct). If the fridge is running at max draw and I have 2 devices plugged into the USB Ports, would there be a chance of a fire/wire melting? or will one of the outputs just not be sufficiently powered? to follow up, could I just use a thicker gauge wire with the socket to allow for more current?
5. For the wiring to the bed. Please correct me if I'm wrong:
- 10A (Fridge) + 6.5A (USB Ports per Amazon description "Output of each usb port : DC 3.6-6.5V/3A, 6.5V-9V/2A, 9V-12V/1.5A") + 2A (24W LED Strip) = 18.5A therefore 12 AWG or 10 AWG power and ground wire depending on length of wire then use two 14 AWG wire to the 12V socket & Led Lights
6. Should I go with the largest possible gauge (probably 4 AWG) between the battery and switch-pros/blue sea busbar since I'm already at 28.5A (at max draw) for these alone? Keep in mind that in the future, I'm planning to install a compressor, roof rack spot lights (KC Hilites Gravity Pro6), ditch lights, bumper lights, chase bar.


I've researched before posting but it will give me peace of mind hearing answers to my specific questions.


Links:
Switch-Pros: SP-9100 Switch Panel Power System
PowerTrays Mount: Switch-Pros PowerTray > Tacoma > TRD Off Road/Pro
BlueSea Bundle: Accessory Bundle for Switch-Pro PowerTray > Toyota
20W 4WDKing LED Lights: Link
12v Socket & USB: Link
LED Light Strip (for reference): Link
Blue Sea Wire Selection Reference: http://assets.bluesea.com/files/resources/newsletter/images/DC_wire_selection_chartlg.jpg

 

[M Rose]

From battery to power distribution panel always run the largest gauge of wire you can for several reasons, but the two most important are 1: you can add onto your system later on and not worry about the gauge of feed wires used originally. 2: if you have a failure in your system you will pop a fuse instead of burn a wire.

Directly off the battery I typically run 00 welding wire to a rear mounted fuse panel and grounding junction block. At each end of the positive cable I run a 400 amp manual circuit breaker, this allows for both protection and a convenient switch. Also this configuration allows the addition of a secondary battery or Jackery type power station down the road.

your wire sizes for the rest of the build are spot on...I would use 8 or 10 gauge wires for the fridge. 12-14 gauge on the rest of your circuits.

 

[Trigger T4R]

Not sure on the fridge wiring but with the lights, just run whatever the size wire that the lights come with and you’ll be fine. Without going out to look, I believe most lights use 14 to 18awg depending on the light. I think I used 18awg on all mine just to make it easy and go a bit overkill. Match wire size with accessory coming out of the fuse panel & you’re good. As for wiring the fuse panel, doesn’t the switchpros come with a wiring harness?

My switch panel only uses an 80amp breaker for six switches. Haven’t had a problem. I’m no expert though lol.

 

[Billiebob]

on using wires a guage ot two larger, besides meeting the minimum, the longer the run, or the lighter the gauge, the bigger the voltage drop. keep the wiring runs as short as possible, bump up a gauge, never down.

this is positively idiotic, setting a tiny genset 100 feet from the appliance and running a 16gauge extension cord. If the dog scent marks the genset he'll get a jolt, if he pisses on the appliance, it'll get wet.

 

[Flipper]

A good reference for wire gauge and runs is the Blue Seas website. They also have great customer support and block diagrams. IMO I would try to do all the hardware with BlueSeas. They make a great fuse assy that mount directly to the battery post for your main fuse for the run to the fuse/ terminal. Ancor for the wire and terminals, shrink crimp connectors. You can find that on Amazon. When in doubt or want to make it bulletproof I go up to next gauge.. A good product to waterproof your connections is a product called CRC Heavy Duty Corrosion Inhibitor. Just spray it on all the terminals and connectors when your finished. Split loom when you finish you harness for a clean install and added protection.

 

[Larry de Lobster]

From battery to power distribution panel always run the largest gauge of wire you can for several reasons, but the two most important are 1: you can add onto your system later on and not worry about the gauge of feed wires used originally. 2: if you have a failure in your system you will pop a fuse instead of burn a wire.

Directly off the battery I typically run 00 welding wire to a rear mounted fuse panel and grounding junction block. At each end of the positive cable I run a 400 amp manual circuit breaker, this allows for both protection and a convenient switch. Also this configuration allows the addition of a secondary battery or Jackery type power station down the road.

your wire sizes for the rest of the build are spot on...I would use 8 or 10 gauge wires for the fridge. 12-14 gauge on the rest of your circuits.

I'll have the blue sea fuse box on the powertrays bracket so the rear mounted fuse panel is out of the question. I might just run separate lines ahead of time so I'll only go under the truck once. I'll keep all that in mind for future builds cause that's something I wanna do in the future. Thanks!

Not sure on the fridge wiring but with the lights, just run whatever the size wire that the lights come with and you’ll be fine. Without going out to look, I believe most lights use 14 to 18awg depending on the light. I think I used 18awg on all mine just to make it easy and go a bit overkill. Match wire size with accessory coming out of the fuse panel & you’re good. As for wiring the fuse panel, doesn’t the switchpros come with a wiring harness?

My switch panel only uses an 80amp breaker for six switches. Haven’t had a problem. I’m no expert though lol.

The switch-pros do come with 4-gauge positive wire. The accessory bundle from powertrays come with a 4 gauge set pre-cut for the Tacoma as well. I just wanted to check if it had enough capacity for everything I'd want in the future. Even though I know the likelihood of everything running all at once is small, I still want the entire system to be sized to handle it.

The lights will come with wiring but I don't want it to look messy. I figured making my own harness will make it as clean as possible but I'd have to wait and see once the lights come in.

on using wires a guage ot two larger, besides meeting the minimum, the longer the run, or the lighter the gauge, the bigger the voltage drop. keep the wiring runs as short as possible, bump up a gauge, never down.

this is positively idiotic, setting a tiny genset 100 feet from the appliance and running a 16gauge extension cord. If the dog scent marks the genset he'll get a jolt, if he pisses on the appliance, it'll get wet.

View attachment 187515

I don't think I'll be running anything that long haha but good to know!

A good reference for wire gauge and runs is the Blue Seas website. They also have great customer support and block diagrams. IMO I would try to do all the hardware with BlueSeas. They make a great fuse assy that mount directly to the battery post for your main fuse for the run to the fuse/ terminal. Ancor for the wire and terminals, shrink crimp connectors. You can find that on Amazon. When in doubt or want to make it bulletproof I go up to next gauge.. A good product to waterproof your connections is a product called CRC Heavy Duty Corrosion Inhibitor. Just spray it on all the terminals and connectors when your finished. Split loom when you finish you harness for a clean install and added protection.

I'll be using heat shrink with adhesive on my connections and using wire looms and/or sleeves where appropriate plus silicone paste if needed. I'll be using the OEM Battery posts since I'm only running the single positive wire to the switch pros and I believe the included one from switchpros and powertrays are already fused. I'll look into CRC, haven't read about that yet. Thanks!

 

[leeloo]

I don't think you can make it with a single battery with all that stuff, lights and fridge. Not with a 65L Dometic. You might pull it off with a small engel fridge, but even there I would have some kind of battery booster with me at all times.
You say the fridge draws aprox 9 amp/h. Lets say it functions 30 % of the time, optimistic.
You camp, stop the engine at 6 PM, and leave camp at 8 A.M. That means you need to power the fridge for 14 hours and, it will run for 4-5 hours that means you need 40 to 50 amps.
A 90 amp start battery( who knows what you on your vehicle, might be smaller ) , that is not deep cycle at 50 % is considered dead, as in really dead...
Even if by some miracle you can start the car in the morning, you will kill the battery fast, normal start batteries don't go well with deep discharges..
With charging equipment, it comes back to life but you do this 4, 5 times and it is done... you need a new one.

I have a fridge, and in a hot summer night with many beers drank ( so I would put more beers inside to cool ) and according to the voltage chart in the morning it was at 70 % and my fridge draws a lot less than what you are saying yours does. ..
I have a 100 Ah deep cycle secondary battery, and after I added solar and changed the fridge to a more efficient one is a bit overkill. On the other hand now I can easily add an inverter as well and charge laptops or other stuff that requires AC....

 

[ruralpunk]

I don't think you can make it with a single battery with all that stuff, lights and fridge. Not with a 65L Dometic. You might pull it off with a small engel fridge, but even there I would have some kind of battery booster with me at all times.
You say the fridge draws aprox 9 amp/h. Lets say it functions 30 % of the time, optimistic.
You camp, stop the engine at 6 PM, and leave camp at 8 A.M. That means you need to power the fridge for 14 hours and, it will run for 4-5 hours that means you need 40 to 50 amps.
A 90 amp start battery( who knows what you on your vehicle, might be smaller ) , that is not deep cycle at 50 % is considered dead, as in really dead...
Even if by some miracle you can start the car in the morning, you will kill the battery fast, normal start batteries don't go well with deep discharges..
With charging equipment, it comes back to life but you do this 4, 5 times and it is done... you need a new one.

I have a fridge, and in a hot summer night with many beers drank ( so I would put more beers inside to cool ) and according to the voltage chart in the morning it was at 70 % and my fridge draws a lot less than what you are saying yours does. ..
I have a 100 Ah deep cycle secondary battery, and after I added solar and changed the fridge to a more efficient one is a bit overkill. On the other hand now I can easily add an inverter as well and charge laptops or other stuff that requires AC....

I cant agree with @leeloo enough. The reason for getting a secondary battery is because the way a traditional lead-acid battery is designed is to draw high amperage while starting, but because of that it only works when fully charged (like 80-100%), unless you keep your rig running 24/7 you will be going through batteries every other trip.

The best way to think about it is that the lead-acid under your hood is for the vehicle ONLY. You can run other stuff from there, but the engine HAS to be running. The secondary battery (can be deep cycle or lithium ion) if for fridge/camp lights etc. It's important to keep the systems separate to protect you main vehicle battery.

I hope this helps and doesn't just come across as "my way is the right way". It really is important to protect the health of your vehicles main lead acid battery, unless you like hiking out.

 

[KF0APA]

As stated in many replies before this one, you're going to need a second battery. I run 2 deep cycle batteries under my hood, and I have a 3rd in the back of my Yukon. Wife thought it was overkill until the guys we were with had battery issues (they only had 1) we were able to jump start them, and then finally loaned them our 3rd battery to get them home. Good luck with this project, I hope you'll post updates on it.

 

[Larry de Lobster]

I don't think you can make it with a single battery with all that stuff, lights and fridge. Not with a 65L Dometic. You might pull it off with a small engel fridge, but even there I would have some kind of battery booster with me at all times.
You say the fridge draws aprox 9 amp/h. Lets say it functions 30 % of the time, optimistic.
You camp, stop the engine at 6 PM, and leave camp at 8 A.M. That means you need to power the fridge for 14 hours and, it will run for 4-5 hours that means you need 40 to 50 amps.
A 90 amp start battery( who knows what you on your vehicle, might be smaller ) , that is not deep cycle at 50 % is considered dead, as in really dead...
Even if by some miracle you can start the car in the morning, you will kill the battery fast, normal start batteries don't go well with deep discharges..
With charging equipment, it comes back to life but you do this 4, 5 times and it is done... you need a new one.

I have a fridge, and in a hot summer night with many beers drank ( so I would put more beers inside to cool ) and according to the voltage chart in the morning it was at 70 % and my fridge draws a lot less than what you are saying yours does. ..
I have a 100 Ah deep cycle secondary battery, and after I added solar and changed the fridge to a more efficient one is a bit overkill. On the other hand now I can easily add an inverter as well and charge laptops or other stuff that requires AC....

I cant agree with @leeloo enough. The reason for getting a secondary battery is because the way a traditional lead-acid battery is designed is to draw high amperage while starting, but because of that it only works when fully charged (like 80-100%), unless you keep your rig running 24/7 you will be going through batteries every other trip.

The best way to think about it is that the lead-acid under your hood is for the vehicle ONLY. You can run other stuff from there, but the engine HAS to be running. The secondary battery (can be deep cycle or lithium ion) if for fridge/camp lights etc. It's important to keep the systems separate to protect you main vehicle battery.

I hope this helps and doesn't just come across as "my way is the right way". It really is important to protect the health of your vehicles main lead acid battery, unless you like hiking out.

As stated in many replies before this one, you're going to need a second battery. I run 2 deep cycle batteries under my hood, and I have a 3rd in the back of my Yukon. Wife thought it was overkill until the guys we were with had battery issues (they only had 1) we were able to jump start them, and then finally loaned them our 3rd battery to get them home. Good luck with this project, I hope you'll post updates on it.

A bit late on the reply but I've taken the truck on two trips since then (one with the switch pros installed). I ended up running my dometic cfx 75dz off of a jackery 500 connected to the 110v on the truck bed. It works for now but I did run into problems. 1 - sometimes I forgot to turn on the inverter so the battery didn't charge when I was driving. 2 - when the fridge reaches temp, it throttles down the power enough to where the jackery doesn't sense the fridge and shuts off. This happened multiple times and while the fridge section was fine, the freezer side (with ice cream sandwiches) thawed a little. Not a big deal but a problem. I will post picture of the actual install on this thread but here is the camp/scene lights in action. Wish I had better photos but it was definitely useful, especially when we ended up wheeling at night (5+ hrs at night on river road east to river road west at big bend national park).

Also, I will take any constructive criticism on my set up. I'd rather get it right than get my pride and ego involved and end up paying the consequences when I'm out in the middle of nowhere. I will eventually go with a dual battery set up to power all the accessories and leave the starter battery alone. Thanks!