What gauge wire from batteries to inverter

[opnspaces]

I am going to install an inverter in my trailer and am curious about what gauge wire I need to run from the batteries. To be honest I really don't have an application or device I want to run off it. I just want to do it for the "because I can" factor. I plan to mount the inverter against the front wall of the trailer so I don't imagine more that ten feet of DC wiring from batteries to inverter. Below is what I have to work with since I already own them.

A Zamp 2000 watt pure sine model ZP-2000ps. What gauge wire would I need to get optimal use from this? (Figure 10 feet from battery to inverter). This is the one I'll probably use as this is what I had in mind when I bought it.

or

a Zamp 600 watt pure sine model ZP-600ps. What gauge wire would I need if I decided to install this model instead. (Figure 10 feet from battery to inverter).



Is voltage drop a concern in this kind of setup, or is that mostly a concern with solar installs?

Thanks

[2oldman]

theoldwizard1 wrote:

2oldman wrote:
Some of us have gone to 24 or 48 volts to lessen line loss and use thinner, more flexible wire.

A very wise decision, but it makes charging and powering 12VDC item more of a challenge.

As mentioned:

GordonThree wrote:
An inexpensive DC-DC converter provides 12v for small loads like pump, lights, etc.

[theoldwizard1]

2oldman wrote:
Some of us have gone to 24 or 48 volts to lessen line loss and use thinner, more flexible wire.

A very wise decision, but it makes charging and powering 12VDC item more of a challenge.

[BFL13]

SoundGuy, putting an AGM in there will also reduce your tongue weight so you can carry more heavy things in the truck. Or you could use that space for more propane bottles.

The AGM does not need to be accessible for checking its water and doing an hydrometer check, so no issues having it in there and having to pull it out every so often.

You do need an ammeter on it to know you are fully charged, as discussed in other threads on that. I use the Trimetric for that.

In the 5er, I cut a hole in the cargo bay door and inserted one of those plastic "cable hatches" (about $15) which also acted as an air vent when the door is closed and locked. (I had flooded batts) That also helped keep it cooler for the electronic items.

[SoundGuy]

opnspaces wrote:
As far as the distance, the horizontal run is not that far, more like 3 feet if I went straight from the batteries through the front wall of the trailer.

SoundGuy wrote:
I wouldn't do that - if the inverter is mounted in the front pass through storage compartment go down through the floor, along the underside of the A-frame, and up to the batteries.

brulaz wrote:
Oh I dunno. That's what I did. 🙂 As straight a path to the batteries as possible, carefully caulked.

But my front wall consists of a cap + space + interior wall.

The OP's 2005 Jayco Jay Flight 27BH is conventional build, doesn't have a front cap, as is no different in construction than my own 2014 Coachmen Freedom Express in which I installed a 1000 watt PSW inverter in the front pass through storage compartment and ran the cables from the inverter down through the floor to the battery.



This upcoming season I have to replace my now failed 10 yr old Interstate battery, most likely with a single G31 as we normally only "dry camp" those few times each season we lose shore power. It'll fit in the same battery box I have mounted on the tongue but if I go for the additional cost of an AGM I'm considering parking it in the pass through storage compartment just below the inverter, in which case the cable run from the inverter to the battery will be shortened from 6' to ~ 15". Thinking out loud I might even bring the battery's negative & positive posts out to lugs mounted next to the street side hatch door so I can readily load support that G31 & inverter with the truck those times I may want to power a heavy draw appliance such as my toaster. For those of us who do this only occasionally load support works just fine and is a lot less costly than investing in a set of dual or quad batteries.

[brulaz]

SoundGuy wrote:

opnspaces wrote:
As far as the distance, the horizontal run is not that far, more like 3 feet if I went straight from the batteries through the front wall of the trailer. But that seems like a leak point so I was picturing going down from the batteries, back to the trailer then up through the floor. Now that I have a better idea how much distance affects wire gauge, voltage drop, and price; I'm going to reconsider the path to see how much I can shorten it.

I wouldn't do that - if the inverter is mounted in the front pass through storage compartment go down through the floor, along the underside of the A-frame, and up to the batteries. In my case that turned out to be 6', meaning 12' of cable for positive & negative, both 4 gauge for my maximum ever load of 70 amps. You sure don't want to go through the trailer's front wall - instead increase the gauge of the cable to whatever may be necessary to meet your load & distance requirements.

Oh I dunno. That's what I did. 🙂 As straight a path to the batteries as possible, carefully caulked.

But my front wall consists of a cap + space + interior wall. A water leak will just drain down the solid fibreglass cap. If that front surface were laminate ... maybe not.

[GordonThree]

Whatever wire size you land on, select the fuse to fit the wire, rather than whatever the inverter wants. #4 ga, 80 amp fuse is all I'd gamble.

[SoundGuy]

opnspaces wrote:
As far as the distance, the horizontal run is not that far, more like 3 feet if I went straight from the batteries through the front wall of the trailer. But that seems like a leak point so I was picturing going down from the batteries, back to the trailer then up through the floor. Now that I have a better idea how much distance affects wire gauge, voltage drop, and price; I'm going to reconsider the path to see how much I can shorten it.

I wouldn't do that - if the inverter is mounted in the front pass through storage compartment go down through the floor, along the underside of the A-frame, and up to the batteries. In my case that turned out to be 6', meaning 12' of cable for positive & negative, both 4 gauge for my maximum ever load of 70 amps. You sure don't want to go through the trailer's front wall - instead increase the gauge of the cable to whatever may be necessary to meet your load & distance requirements.

[opnspaces]

SoundGuy wrote:
The question though in your case is, aside from heavy wiring necessary to make the most of a 2000 watt inverter what do you intend to use to power the inverter, 'cause a single battery sure isn't going to do it? :h

True I realize it takes a lot of battery to support a large load. Currently I'm running two 6volt Costco batteries and am working on upgrading my original charger to something more robust than the stock charger that came in the trailer. I would like to add two more 6 volts in the future, but I'm not yet sure where I want to put them.

When I look at my inverter it has 1 positive and 1 negative lug. They look to be about 3/8 inch or 10mm across so I should be able to add a fairly large wire and terminal.

Thanks everyone for your input on this.

[opnspaces]

pianotuna wrote:
opnspaces,

Zamp is pricey compared to some other inverters. Unless you have it already I'd suggest something else.

The inverter needs to be as close as humanly possible to the battery bank without being in the same compartment.

My wire run is about four feet--and that is LONG for a 3k unit.

Thanks Pianotuna, Yes I already have the inverter thanks to Lowes clearing them out a few months back. So now that I have it I figure I should use it rather than leaving it on the shelf in my garage where it's been since it's purchase.

[opnspaces]

MEXICOWANDERER wrote:
Here's a real world tip about voltage drop influence...

Coffeemaker 950 watts

24 oz brew 55F water

At 120vac one minute fifteen seconds

At 100vac two minutes thirty (five?) seconds

Microwave. 8oz russet potato

Seven minutes

Eleven and a half minutes


" Need 4x #10 to make #4 "
Double wire drop three sizes 2x10 9-8-7 (seven gauge)
Works with AWG. SAE wire gauge doesn't cut it...

Thanks for the reply

Wow I never would have thought that 20V AC, or lack of it, would have that much effect.

So I was right on the parallel wires, 2x10 = 7. I figured it wasn't a straight multiplier.

Thanks

[opnspaces]

GordonThree wrote:
10 gauge is speaker wire, not suitable for an inverter. Where did 10 gauge come from?

Why is the inverter being installed so far from the batteries?

The 10 gauge was just a theoretical question as I've just always wondered, just never remembered to ask until this post.

As far as the distance, the horizontal run is not that far, more like 3 feet if I went straight from the batteries through the front wall of the trailer. But that seems like a leak point so I was picturing going down from the batteries, back to the trailer then up through the floor. Now that I have a better idea how much distance affects wire gauge, voltage drop, and price; I'm going to reconsider the path to see how much I can shorten it.

Thanks

[opnspaces]

time2roll wrote:
If the tag says 13 amps load you can count on close to 130 amps from the 12 volt battery. (amps x10)
Best to stay away from parallel wires unless the inverter has dual input terminals. Get the right stuff. I posted a link above.

As far as equivalent wire you need to convert to circular mils to add the cross section of copper. But again try to stay away from parallel.
Cross section area is on this ampacity chart:
http://www.genuinedealz.com/voltage-drop-calculator
Need 4x #10 to make #4

I didn't think I was calculating that correctly. So that's 130 Amps. Is there a time factor in that? actually I think I'll start a new post for that question so this hopefully stays on track.
And thanks for the link above for ordering wire. I try to support the local guy so I'll try the local welding supplier first. But if the price difference is large enough I'll have to go online.

[BFL13]

GordonThree wrote:
Gotta love AGM for their flexibility. My setup sounds sounds similar to BFL13's ... I have my 2800w inverter snuggled with four G31 12v AGM under a heavily reinforced dinette seat. More than four years now, no issues with anything. It's a bit untidy, I left slack in my 4/0 welding cable to be able to pull out the inverter without disconnecting the batteries, for troubleshooting or whatever.

Load test, run the 13.5 A/C and the microwave, the inverter heats up a bit, that fan gets going good but the battery cables stay nice and cool while carrying almost 300 amps.

Sort of. In our Class C, the regular sealed/vented battery box is under a dinette seat. It will hold two 6s or similar. Has access door to outside.

I put the two AGMs inside under the sink counter for the inverter-only job, and still have the OEM battery box under the dinette for the regular 12v job the house batts do. I gave each battery bank its own converter/charger and solar set. (I also have a second set of batteries added to the "house 12v set" but down farther in another outside compartment, making four that do the 12v stuff. Had to drill holes to pass wires.

So in a TT I would leave the tongue battery bank as is, and use it for the same old 12v stuff, and add a second battery bank of AGMs inside just to do the inverter 120v stuff.

I really like having the inverter 11v alarm business free from the regular house batts, that might get too low running the furnace and then not be able to make toast using the 120v toaster for breakfast. Yipes! Have to use the horrible bread-burner on top of the propane stove for making toast? Never again! 😞

[pianotuna]

Hi,

I'd go for a 48 volt system with a 48 dc to 12 dc converter to power the standard house loads.

For a really cool system there is now a way to use individual grid tied inverters on an RV. This simplifies the system by eliminating the charge controller, and #12 wire can be used from the panels to the inverter.

[GordonThree]

Gotta love AGM for their flexibility. My setup sounds sounds similar to BFL13's ... I have my 2800w inverter snuggled with four G31 12v AGM under a heavily reinforced dinette seat. More than four years now, no issues with anything. It's a bit untidy, I left slack in my 4/0 welding cable to be able to pull out the inverter without disconnecting the batteries, for troubleshooting or whatever.

Load test, run the 13.5 A/C and the microwave, the inverter heats up a bit, that fan gets going good but the battery cables stay nice and cool while carrying almost 300 amps.