200 amps to the rear of a power wagon?

[Roloc]

Ok so have done plenty of one wire installs to lights, 12v sockets etc all connecting to something like an SPOD or recently Garmin power switch but I am planning on doing a little more complex install to the back of my camper when I get my second battery mount.

So admittedly this is probably WAY over engineered for what I will need but now I am using it as a way to learn.

So with the disclaimers out of the way... help me through this please.

I was planning on installing a fuse box AND a Garmin power switch. The thinking here is I would have some always on items (fridge, voltage meter/manager, Rear facing camera etc). then I would have some switched items like camp lights, awning lights... just basically various kinds of lights).

SOOO the fuse box would hold the always on things, and the Garmin PowerSwitch would hold the switched items. The power switch can take 100amps and the Fusebox can take 100amps.

So I was going to run 200amps to the rear with fuses near the second battery and then 200amp BUS to the Fuse box and the Garmin power switch with 100amp fuses in between the two and the bus.

All of that seemed logical until I tried to calculate what gauge wire I would need and to go the estimated 22 feet from the front of the power wagon along the outside and into the camper the internets say I need a 1AWG or 1/0 gauge cable?! That seems huge from my old school AMP in the trunk and 15" subwoofer days.

Is that true? or am I missing something here. I know I won't be drawing the full 200amps all the time but I also don't want to do this again anytime soon so I was trying to future proof.

Any ideas? Or please tell me I am an idiot for missing something.

Reference wire size chart: 12 Volt Wiring: Wire Gauge to Amps |

 

[M Rose]

Ok so have done plenty of one wire installs to lights, 12v sockets etc all connecting to something like an SPOD or recently Garmin power switch but I am planning on doing a little more complex install to the back of my camper when I get my second battery mount.

So admittedly this is probably WAY over engineered for what I will need but now I am using it as a way to learn.

So with the disclaimers out of the way... help me through this please.

I was planning on installing a fuse box AND a Garmin power switch. The thinking here is I would have some always on items (fridge, voltage meter/manager, Rear facing camera etc). then I would have some switched items like camp lights, awning lights... just basically various kinds of lights).

SOOO the fuse box would hold the always on things, and the Garmin PowerSwitch would hold the switched items. The power switch can take 100amps and the Fusebox can take 100amps.

So I was going to run 200amps to the rear with fuses near the second battery and then 200amp BUS to the Fuse box and the Garmin power switch with 100amp fuses in between the two and the bus.

All of that seemed logical until I tried to calculate what gauge wire I would need and to go the estimated 22 feet from the front of the power wagon along the outside and into the camper the internets say I need a 1AWG cable?!

Is that true? or am I missing something here. I know I won't be drawing the full 200amps all the time but I also don't want to do this again anytime soon so I was trying to future proof.

Any ideas? Or please tell me I am an idiot for missing something.

Reference wire size chart: 12 Volt Wiring: Wire Gauge to Amps |

1 gauge for that length of run for 200 amps is the absolute minimum I would run… Personally I use 00 welding lead wire for all my main battery cables. Thicker insulation, more copper strands, very flexible, and if bought at the welding store a 50’ cable generally runs about $25.00 USD.

 

[Roloc]

1 gauge for that length of run for 200 amps is the absolute minimum I would run… Personally I use 00 welding lead wire for all my main battery cables. Thicker insulation, more copper strands, very flexible, and if bought at the welding store a 50’ cable generally runs about $25.00 USD.

Awesome that makes me think I am not insane because no where in there did you laugh at me and tell me I was going about this all wrong :) so that itself is very helpful.

Any chance you can send me a link to that cable? The stuff I am looking at on amazon or anywhere online is $100+ for 50' not sure if overland bound allows linking to other stores if they don't can you DM me? Thanks a ton!

 

[M Rose]

Awesome that makes me think I am not insane because no where in there did you laugh at me and tell me I was going about this all wrong :) so that itself is very helpful.

Any chance you can send me a link to that cable? The stuff I am looking at on amazon or anywhere online is $100+ for 50' not sure if overland bound allows linking to other stores if they don't can you DM me? Thanks a ton!

I buy at local welding stores… they typically don’t have online inventories, and the ones I frequent do not.

 

[Roloc]

I buy at local welding stores… they typically don’t have online inventories, and the ones I frequent do not.

Sounds like I have a fun weekend hunt ahead of me! Thanks for the help I really appreciate it.

 

[madcratebuilder]

Like Mike said 00 is the minimum I would run. You may want to rent/buy/borrow a hyd crimp tool for installing terminals. Horrible Freight has one for a reasonable price.

 

[Roloc]

Like Mike said 00 is the minimum I would run. You may want to rent/buy/borrow a hyd crimp tool for installing terminals. Horrible Freight has one for a reasonable price.

Thanks yeah that got added to the list when I was heading down the rabbit hole last night. This should be a fun install trying to put in this angled area of a box I have on the camper so fun with angle cuts and such too!

going to USA SB350 Anderson connection to to the whole box and determined I can probably do the same for my portable ARB compressor instead of the battery clamp. This is going to be fun if I don’t manage to blow myself up in the process!

 

[Roloc]

So I got some 2/0 to run and it was about $4.80 per foot from a welding store. They didn't have lead in that size, but yikes 60 feet of it I just closed my eyes and handed him the credit card.

 

[Sparksalot]

So I got some 2/0 to run and it was about $4.80 per foot from a welding store. They didn't have lead in that size, but yikes 60 feet of it I just closed my eyes and handed him the credit card.

Which store did you go to?

 

[Roloc]

Which store did you go to?

Ohh hello fellow Texan

Hofmann’s supply in San Marcos

 

[Roloc]

Ok follow up here If I am running 200amps on the positive cable to the rear would you all run the same size cable back to the negative of the second battery or just run the same size cable to a ground somewhere near the rear such as the frame?

Trust me I just went down a rabbit hole of "where to ground your second battery" and it appears the internet is torn this where some say frame, some say engine block, wire the two negative terminals to each other and even wire to the same place the main battery is grounded.

I figured you folks in this thread has steered me straight thus far so I figured I would ask. Where should I run the ground from the bus bar in the back? and where should I ground the second battery?

 

[Sparksalot]

The answer is it depends. Some do not care, a ground path is a ground path. Others may definitely have issues if you you the frame as a return path, because the computers will see different impedances than expected.

 

[M Rose]

Ok follow up here If I am running 200amps on the positive cable to the rear would you all run the same size cable back to the negative of the second battery or just run the same size cable to a ground somewhere near the rear such as the frame?

Trust me I just went down a rabbit hole of "where to ground your second battery" and it appears the internet is torn this where some say frame, some say engine block, wire the two negative terminals to each other and even wire to the same place the main battery is grounded.

I figured you folks in this thread has steered me straight thus far so I figured I would ask. Where should I run the ground from the bus bar in the back? and where should I ground the second battery?

Rule of thumb: Use the same length/gauge wire for both positive and negative battery terminals.

 

[Roloc]

Rule of thumb: Use the same length/gauge wire for both positive and negative battery terminals.

ok so if I ground it near the rear of the truck and I get issues then try another location? Or should I start by grounding the second battery to the main battery?

 

[Kozysnack]

Ohh hello fellow Texan

Hofmann’s supply in San Marcos

Ok follow up here If I am running 200amps on the positive cable to the rear would you all run the same size cable back to the negative of the second battery or just run the same size cable to a ground somewhere near the rear such as the frame?

Trust me I just went down a rabbit hole of "where to ground your second battery" and it appears the internet is torn this where some say frame, some say engine block, wire the two negative terminals to each other and even wire to the same place the main battery is grounded.

I figured you folks in this thread has steered me straight thus far so I figured I would ask. Where should I run the ground from the bus bar in the back? and where should I ground the second battery?

i learning vicariously

 

[M Rose]

ok so if I ground it near the rear of the truck and I get issues then try another location? Or should I start by grounding the second battery to the main battery?

Run a dedicated ground cable from main battery to the auxiliary battery

 

[Roloc]

Run a dedicated ground cable from main battery to the auxiliary battery

awesome thank you. That’s what felt normal to me but after going down the rabbit hole I got confused.

 

[Kozysnack]

can't wait to see some photos of your progress!

 

[Roloc]

can't wait to see some photos of your progress!

I'll for sure update the build thread. This is like the last thing on my list! Well.. for now...

 

[slomatt]

200A is quite a lot of power, and the cable size required to support that would be expensive and heavy, so my first question is do you really need that kind of amperage capacity. :)

1) Is the plan to put a second battery in the camper? If so, how do you plan to charge it? If charging off the alternator using a DC-DC system then you really only need to tie the batteries together with wire sized to handle the output of the DC-DC charger. Then you could just run your accessories off the second battery, and not need large wires to the front battery.

2) What is the expected total draw of all your accessories? LED lights and a fridge don't draw that much, so even if you were running them off the main battery in the engine bay I think 200A would be overkill. On the other hand, if you are using an induction stove or larger air compressor that could increase your needs.


Even if the Garmin PowerSwitch and fuse block are each rated for 100A that doesn't mean you'll ever realistically need that kind of power. You can definitely use a smaller wire to power them as long as it is protected with an appropriately sized fuse, it just means that you wouldn't be able to load both to their maximum capacity at the same time.