Looks good. 2/0 and 200A is bigger than you need and would be enough for a 2000w inverter. (the breaker will only trip on steady loads, not surge) But bigger does not hurt anything, just costs more. I have installed at least 100 inverters like this for off grid solar over the past 40 years.

 

I was just going from this chart : Recommended Inverter Cable, Breaker & Fuse Sizing | DIY Solar

 

I have a 1000W Renogy inverter that's worked continuously for 2.5 years running a backup 4.5cu/ft refrigerator. There is one feature that some inverters like this have, a built in GFI circuit breaker. It causes an immediate shutdown for some appliances like an upscale frost free refrigerator.

 

Out of curiosity, does anyone know the gauge of wire that VW uses between the 12v battery and the visible distribution bus?

 

Oh I make my own cables too using the same technique. I was asking about a source for individual components.

ebay.

Out of curiosity, does anyone know the gauge of wire that VW uses between the 12v battery and the visible distribution bus?

VWtech said the spare terminal on the bus is limited to 60A.

 

ebay.

VWtech said the spare terminal on the bus is limited to 60A.

Right. But I was asking about the primary cable from the battery to the bus bar. Is it 2/0?

 

I personally would be leery about having a heavy continuous load on the 12 volt battery, given the complexity of everything else connected to, and dependent on it. A few years ago I had a Jeep with a Mercedes Diesel engine, and was running a lot of electronic gear doing on-road radio-frequency measurements. The equipment only pulled 10-15 amps total, but it meant that the battery was under continuous charge. Even though the diesel battery was rated for deep discharge, after a week of several hours a day operation, it gave up.

Even at 1 kilowatt or so, you will be pulling 100 amps continuously, and the on-board battery charger probably isn't rated for continuous dissipation for several hours.

 

All fair points. The good news is that the ID system is water cooled and as has been demonstrated elsewhere in these forums that the 12v battery is constantly being charged by the HV battery. As such it is quite different situation than “depleting” your Jeep battery while running your gear. Instead it would be more akin to you running the Jeep’s diesel motor while using your electric loads — I suspect in such a case your battery would have fared quite well.

 

I've had good experiences with "Wire and Cable Your Way":

https://www.wireandcableyourway.com/2-0-battery-cable-type-sgx

 

Thanks! I had forgotten about them! Yeah, good guys for sure.

 

It appears from my measurements that the primary 12v cable is 1 gauge. Ergo, there is no reason to use any greater than that for my 12v to 120v inverter project. Does that make sense?

 

It appears from my measurements that the primary 12v cable is 1 gauge. Ergo, there is no reason to use any greater than that for my 12v to 120v inverter project. Does that make sense?

Yes the bus bar is bolted directly to the battery + so that wire size does not matter for this. There are nice threaded connections under the red and black caps labeled + and - for jump starting, and that is the best connection point as shown in the previous big inverter thread here:

https://www.vwidtalk.com/posts/170658/

 

And here is my first attempt at a layout. I think everything will clear as well as not get in the way of servicing the vehicle.

 

1AWG copper maxes at 145A, so that's just over 2kW at 14V and ~1.7kW at 12V.

Your reasoning makes sense based on what's feeding the battery to keep it charged, but it may still make sense to go a bit larger to allow you to pull larger loads directly from the battery.

I wouldn't pull larger loads than probably 1,500W with 1AWG cable.

 

That’s the goal. Basically to have an “emergency” 15A 120V outlet.

 

Well looking at price of stuff I might go with 1/0 gauge since Amazon offers that for less than 1gauge from a reputable source. Gosh I hate giving them my money.

 

Well looking at price of stuff I might go with 1/0 gauge since Amazon offers that for less than 1gauge from a reputable source.

This is why I cut all my cable from DC fast chargers. And usually by the time I go back there again, they've already grown back!

 

You should either size up your connector or size down your breaker. You want the breaker to trip before you melt your connector.

Edit: Nevermind, I see you are using a 150A breaker in your mockup picture.

 

So this is the inverter I purchased for this project.
I'm wondering if I should now go with a 200A breaker together with 1/0 cable?

Giandel 2000W Inverter Review

 

Progress so far (waiting on the wire and connectors):

 

Ok, who here said I need at least 1/0 gauge for this project? This stuff is significantly bigger than anything that our ID.4s use. Not complaining but it does seem like overkill. I guess I can always claim bragging rights.

 

1/0 is serious!

 

1/0 is seriousl.

Ya think?

 

Whoever here suggested 1/0 cable for a 1500w inverter is an idiot. Here’s a detail of a binding post from a 2000w inverter as compared to 1/0 copper cable. Total overkill. At most 1 gauge would be more than enough to handle such use cases. Lesson? Don’t listen to idiots on the web. YMMV.

 

Ok. A me culpa is appropriate here. I suggested previously that only idiots would recommend 1/0 gauge cable (or greater) for use with a 1500W 12V DC inverter. It turns out that I am indeed the idiot. Not surprisingly, there are two things at play here: the idiocy of assuming that Amazon/Alibaba products for sale on the internet had a modicum of truth to their claims. The other is the idiocy of believing in the fallacy that those with knowledge of "best practices" would understand the previous point and be able to quantify their knowledge in such a way that us mere-mortals might fully grok.

Anyway, the well-recommended Giantel 2000W 12v - 120v Inverter (that I recently purchased from Amazon) specs imply that the item can deliver 2000W continuously (as do pretty much all other similar Chinese products). The issue appears to be how one defines the term "continuously". Additionally, on YouTube there are plenty of reviews of such inexpensive Chinese inverters that convincingly show these items do in fact deliver in the real-world.

That being said, people who are subject-matter experts on the matter clearly understand that such a claim should mean, to anyone with a brain of course, that it means 24/7 CONTINUOUSLY. Duh. What else could it mean? Whereas the Chinese manufacturers of such inverters likely assume that continuously means "in the context of typical household usage of energy over the course of a day".

How do I come to this conclusion?

Well, I opened up said 2000W inverter (see attached photo) and discovered that the cabling from the exterior mounting lugs to the (obviously interior) circuit board -- where I could see with my little eye -- get this: two 10 AWG cables per circuit! (or put another way, the internal pair are only equal to a single 5 AWG cable). So we have a discrepancy here. If we assume that 5 AWG is promoted to satisfy the energy requirements of a 2000W load and if we also assume 1/0 AWG is the officially published sizing to satisfy the energy requirements of a theoretical 2000W load, then we have a discrepancy of approximately 55/20, or 2.75)

Now if we then take 24 hrs / 2.75 we end up with approximately 9 hrs. Ergo my hypothesis: the Chinese manufacturers have decided that "continuously" should mean something like: "this thing can run continuously for X hours at full load, beyond which we ain't responsible in the real world". To further simplify things, I would round that to 8hrs or 1/3 of a day (or more accurately, 1/3 of forever, or more to the point 1/3 of continuously). Which means what? That likely that the generally-assumed idea of what it means to be a "2000W 12v to 120v inverter" is a device that will work in-the-real-world "continuously connected to" most normal, ordinary, real-world, modern household loads. A mouthful, but not necessarily a lie either. A begrudging duh is somewhat in order I guess. Anyway, I believe this is the core of the discrepancy. However I'm open to further enlightenment.

Dang, after that diatribe (which felt good btw), I'm still not sure if I should keep this puppy or not? Given my use case of course...

 

Not all the chinese inverters are bad, I bought this WZRELB one, I used it daily for over a year at 1700-1800w continuous charging my car. It got better reviews than other made in china brands.

Pardon Our Interruption...

 

So here’s the question: how does one know that the item you purchased a year (or two?) ago will today be any better than what I just ordered?

 

FWIW, here is an internal photo showing four 10AWG wires per lug going to four transformers. That is the equivalent of a single 4AWG cable which can handle approximately 200A or 2400W at 0-4ft, so I think I will keep the unit. One thing for sure: unless you are running long lengths of 12v cable, 2AWG is more than enough for a typical 2000W inverter. 1/0AWG is indeed overkill for this application. YMMV.

 

From wire ampacity charts:

120V x 15A (12A) = 1,800W (1,440W) 14 AWG copper 60°C residential
at 90% inverter efficiency:
12V x 167A (133A) = 2,000W (1,600W) 1/0 AWG copper 90°C minimum
fused at 170A wire rating

(80% continuous)
.

 

yeah, but the reasonably-priced "2000W" inverters generally available online clearly cannot do 80% load. That is my point.

 

Anyway, here’s a photo of my “2000W” inverter with 1/0AWG cables to a 175A Anderson connector.

 

Code is very clear on wire sizing and has not changed on the >40 years I have been doing this. It is also based on the distance. There are different rules that allow smaller wires on short 3" runs inside equipment.

 

Again, it would be actually helpful if people would make the effort to look inside their devices and confirm what these manufacturers are using. It’s safe bet that in most cases they are almost certainly using four 6” to 10” lengths of 10AWG for those “2000w” inverters. AFAIK, most pro electric guides don’t distinguish any significant differences between 6” versus 36” in the sizes we are talking about.

 

While waiting for the last parts to arrive before doing a first in situ test, there is the issue of where the best place inside the frunk area to connect the inverter to chassis ground. Originally I was thinking just connecting it to 12v negative but I’m betting that there is likely an “ideal” location for such a use case. Suggestions welcomed.

 

I’m betting that there is likely an “ideal” location for such a use case.

Yes the jump start posts with the plastic + and - is ideal as shown in previous inverter threads. Remove the plastic caps and they are both threaded.

 

I’ve decided that grounding the unit to chassis ground makes no sense for my use case as the four tires prevent the vehicle from ever serving as a proper/true ground. Instead I’m simply going to fashion up a short copper spike and when using the unit (for those rare emergencies recall) I will simply drive it into any nearby ground. YMMV.

 

It's called bonding, not grounding. It makes sense for vehicles that carry gasoline or diesel, but not for an EV.

 

Besides putting a chassis at near earth potential, a chassis ground provides a low resistance circuit back to the other side of the power source causing an overcurrent condition that blows a fuse or trips a breaker removing power from said chassis. That’s accomplished with the ground to neutral bond in an entrance service panel.

For example, if a 120V hot wire contacts the refrigerator chassis, a very high current flows through the ground wire back to neutral through that bond. That same high current on the hot side trips the breaker deenergizing the chassis. A refrigerator/appliance powered by a 120V generator or inverter often does not have that ground to neutral bond protection, where there is no true “neutral.” Just two leads 120V apart.

The same is true for 12V automotive equipment, where the battery negative is bonded to the vehicle chassis and the equipment chassis is bonded to the vehicle’s chassis. A 12V hot wire contacting the equipment chassis is effectively shorted back to the battery negative, blowing the fuse on the positive side. That’s why it’s provided for and called for in the installation instructions.

edit to add: what if anything is the ground socket of the inverter 120V receptacle(s) connected to?

 

what if anything is the ground socket of the inverter 120V receptacle(s) connected to?

it is connected directly to the ground on the inverter’s 120v outlet.