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

[SoundGuy]

LittleBill wrote:
pictures above are auto resetting circuit breakers, not sure why we think they are terminal strips

SoundGuy wrote:
On second blush I think you're right, question is what they're for. :h One is easy - the small sofa slide - but the other wouldn't seem to serve any purpose as there's already an auto resetting CB in the positive line coming from the battery that goes on to feed these two CBs, the inputs of which which are jumped together. I'll have to take a closer look once I get the trailer out of winter storage.

LittleBill wrote:
i would hold off replacing or rewiring anything till you have a stronger understanding of how things are wired here.

Obviously :R ... which as I already said I can't do for awhile yet as my trailer is currently in winter storage. 😉 Once I do have it back here at the house it'll be a simple matter to identify just what each circuit does and why it's wired the way it is. Between now and then, if I happen to drop by my dealer I'll take a look at a new 192RBS. 🙂

[LittleBill]

SoundGuy wrote:

LittleBill wrote:
pictures above are auto resetting circuit breakers, not sure why we think they are terminal strips

On second blush I think you're right, question is what they're for. :h One is easy - the small sofa slide - but the other wouldn't seem to serve any purpose as there's already an auto resetting CB in the positive line coming from the battery that goes on to feed these two CBs, the inputs of which which are jumped together. I'll have to take a closer look once I get the trailer out of winter storage.

it most certainly has a purpose, the wires are different gauges the cb's are also different amperage's, since the main cb is rated higher, the branch off circuit breaker is using a smaller gauge wire, thus it will need to have a smaller cb(which i assume it does) to protect the branch wire, same as a main and branch breaker in house hold wiring

i would hold off replacing or rewiring anything till you have a stronger understanding of how things are wired here.

[SoundGuy]

LittleBill wrote:
pictures above are auto resetting circuit breakers, not sure why we think they are terminal strips

On second blush I think you're right, question is what they're for. :h One is easy - the small sofa slide - but the other wouldn't seem to serve any purpose as there's already an auto resetting CB in the positive line coming from the battery that goes on to feed these two CBs, the inputs of which which are jumped together. I'll have to take a closer look once I get the trailer out of winter storage.

[LittleBill]

pictures above are auto resetting circuit breakers, not sure why we think they are terminal strips

[SoundGuy]

SoundGuy wrote:
Typical of many travel trailers mine has these awful terminal strips mounted on the trailer frame just below the front pass through storage compartment.



I'm going to take this opportunity when installing the new G31 AGM to replace those strips with this 7-way weatherproof junction box I bought at Princess Auto today.



My plan is to connect the inverter to the battery with 12" to 18" of 1 or 2 gauge pre-made battery cables, then cut my existing 6' lengths of 4 gauge that had been running from the inverter to the battery on the tongue and instead wire those to this new junction box which will be directly below where the new G31 will be sitting. This will really clean up the entire setup, protect those terminal connections from the elements, and minimize voltage drop between the battery and inverter. :B

mapguy wrote:
Fyi, that 7 way junction box is for trailer light/brake wiring and probably won't support the amps of an inverter as listed.

The inverter wires aren't going anywhere near these terminals but directly to the battery. You're absolutely correct though, this box is intended for light / brake wiring but the size / weight of the threaded studs are exactly the same as those terminals already in use. That said, none of this may matter as the more I look at the above pic the more I'm beginning to believe those aren't just terminal strips but rather auto resetting circuit breakers. I'll know for sure once I take a look but the trailer is in winter storage right now so it'll be awhile before I can verify just what I'd dealing with.

[mapguy]

SoundGuy wrote:

BFL13 wrote:
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.

Yeah, that actually may be a downside as I'm currently only running ~ 13% gross tongue weight as it is and would prefer a bit more ... with a new G31 AGM sitting in the pass through instead of the A-frame that will only worsen the situation. 😞 I've been considering what I could put in that empty battery box sitting on the tongue but just haven't come up with anything yet. :h I could rearrange the A-frame platform again and put the propane tanks back where they originally were just aft of the tongue jack but I much prefer this setup as it is. Gonna have to muse on this a bit more. 😛



Typical of many travel trailers mine has these awful terminal strips mounted on the trailer frame just below the front pass through storage compartment.



I'm going to take this opportunity when installing the new G31 AGM to replace those strips with this 7-way weatherproof junction box I bought at Princess Auto today.



My plan is to connect the inverter to the battery with 12" to 18" of 1 or 2 gauge pre-made battery cables, then cut my existing 6' lengths of 4 gauge that had been running from the inverter to the battery on the tongue and instead wire those to this new junction box which will be directly below where the new G31 will be sitting. This will really clean up the entire setup, protect those terminal connections from the elements, and minimize voltage drop between the battery and inverter. :B

Fyi, that 7 way junction box is for trailer light/brake wiring and probably won't support the amps of an inverter as listed.

[babock]

pianotuna wrote:
I'll have to tell my 700 watt heater that it has no inrush the next time it refuses to operate on a 750 watt inverter. I'll threaten to spank it.

You are correct. A typical heater circuit can have up to 25% increase in inrush current due to to heater element having a much lower resistance when cold until it reaches operating temp. It's not as much as an inductive motor startup current but it's still there.

[SoundGuy]

pianotuna wrote:
I'll have to tell my 700 watt heater that it has no inrush the next time it refuses to operate on a 750 watt inverter.

Surge demand caused by an inductive load that can be many times running current is a different animal than inrush of a resistive circuit which is cold and is only a small percentage greater than it's average running current.

It appears the 1000 watt PSW from Canadian Tire is still lonely. I.E. it is their only PSW unit.

Yep, and still a good deal for what it is even though it's on-sale price has gone up, like everything else. 😉

[pianotuna]

I'll have to tell my 700 watt heater that it has no inrush the next time it refuses to operate on a 750 watt inverter. I'll threaten to spank it.

It appears the 1000 watt PSW from Canadian Tire is still lonely. I.E. it is their only PSW unit.

[SoundGuy]

pianotuna wrote:
Inverters with switched power supplies (all of the cheap units) need to have a higher rating--because their ability to surge is pretty lousy. If a 2k unit is only a few bucks more than a 1k unit--I'd deliberately oversize the component.

Maybe, depends on what you're using it for, what's available, and for how much $$$. Mine is a 1000 watt PSW from Canadian Tire, in reality an NPower inverter, purchased because it's was the only PSW inverter sold at the time by CT and because the sale price of $199 for a PSW of this size couldn't be beat here in Canada. :B Secondly, the only inductive loads my inverter sees is a 30 watt fan so obviously the inverter's surge capability is a non-issue. Both my toaster and coffee maker are resistive loads so surge isn't really an issue with those either. 😉 Bottom line - I don't care about an inverter's surge capability and therefore have no need to buy "over" my needs.

[pianotuna]

Hi,

Yes one needs to look at the whole package.

Inverters with switched power supplies (all of the cheap units) need to have a higher rating--because their ability to surge is pretty lousy. If a 2k unit is only a few bucks more than a 1k unit--I'd deliberately oversize the component.

As you may remember, one of our members here did actually burn out an inverter from repeated overloads. It did run his microwave--but the red overload light was on. It did it several many times and then the magic blue smoke came out.

wolfe10 wrote:
As one can see from answers on this thread, to be a "well though out" electrical package, one must consider many things.

No point in a huge inverter with only a small battery bank!

[wolfe10]

As one can see from answers on this thread, to be a "well though out" electrical package, one must consider many things. No point in going too large on one component and having another severely limit usage.

So, to really get "the best for my application" answers:

What is battery bank size (amp-hrs @ 12 VDC)

What is the largest load (amps @ 120 VAC) that you want to run off the inverter AND, for how long.

Location of components-- how far from battery bank to inverter (shorter distance is better, but not in the same compartment). Remember that for wire gauge, the electrons travel "round trip" so if located 10' from the battery that is 20' of wire.

How "idiot-proof" do you need it. Said another way, one of the simplest wiring solutions is to power the whole 120 VAC panel through the inverter (inverter with built-in transfer switch). BUT (read that big BUT)if someone may walk in and turn the the roof A/C when shore power is off or could go off, you would have a big issue (quickly discharge the battery bank and/or overload the inverter). The "idiot-proof" thing to do is remove those circuits you want to be able to power from the inverter (both hots and neutrals) and move them to a sub-panel supplied by the inverter. Then hot from main panel to inverter for when on shore power or generator.

Again, look at the whole package before making a decision. No point in a huge inverter with only a small battery bank!

[3_tons]

Cable size to a large extent depends on what the demand will be - i.e. whether a resistive or reactive load...Resistive loads (like a hair dryer) are dumb loads and not as problematic as are reactive loads (say a large microwave, or vacuum motor) which will have an initial surge rating of 4-5 times the listed appliance amperage...So for reactive loads (in addition to mere wattage) you must also consider the inverters surge rating, thus cost will vary as not all same wattage inverters will perform the same...Take short cuts and you’ll be a candidate for a project redux - evaluate appliance surge conditions...A low voltage alarm or shutdown at the inverter is often due to a bottleneck caused by undersized or too long of round-trip cable run...Consider too that your future appliance needs may increase the demand on the inverter... For these reasons, from the outset I’d recommend 4-0 welding cables - a slight premium yes, but less voltage drop to inverter (absence of annoying alarms) and cheaper than buying cables twice... Just my experienced opinion...

3 tons

[SoundGuy]

BFL13 wrote:
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.

Yeah, that actually may be a downside as I'm currently only running ~ 13% gross tongue weight as it is and would prefer a bit more ... with a new G31 AGM sitting in the pass through instead of the A-frame that will only worsen the situation. 😞 I've been considering what I could put in that empty battery box sitting on the tongue but just haven't come up with anything yet. :h I could rearrange the A-frame platform again and put the propane tanks back where they originally were just aft of the tongue jack but I much prefer this setup as it is. Gonna have to muse on this a bit more. 😛



Typical of many travel trailers mine has these awful terminal strips mounted on the trailer frame just below the front pass through storage compartment.



I'm going to take this opportunity when installing the new G31 AGM to replace those strips with this 7-way weatherproof junction box I bought at Princess Auto today.



My plan is to connect the inverter to the battery with 12" to 18" of 1 or 2 gauge pre-made battery cables, then cut my existing 6' lengths of 4 gauge that had been running from the inverter to the battery on the tongue and instead wire those to this new junction box which will be directly below where the new G31 will be sitting. This will really clean up the entire setup, protect those terminal connections from the elements, and minimize voltage drop between the battery and inverter. :B