Wire gauge confussion

[Smokejumper98]

Starting to hook up a new system on my Northern Lite TC. I am a little confused as to what size wire to use between the batteries and inverter. I will have two 100ah LiFePo 12v batteries going to a 2000w inverter. When I reference Will's book it says that I can use 4 gauge wire if I keep it under 7ft for around 200A. Whenever I research on the web I get varying answers but most call for at least 1/0 if not 2/0 wire for this. My question is can I use 2AWG for about 4' of run.

 

[MisterSandals]

LiFePo

Lithium iron polonium?

2000w inverter.

2000W / 10V cutoff / .85 efficiency = 235A

For even the shortest wire run you are off this charge. Just be sure to size the fuse to protect whatever wire you use.

 

[Tomthumb62]

@MisterSandals gives you a good chart and math. You want 2/0. Not sure why Will recommends 4AWG in his book, it just doesn't make sense. My only guess is that on a 2000W inverter, "most people" never use 2000W continuously. But you can't always control who is going to to use the inverter for what or if you're the only user you might not be so quick to do the mental math "how many watts have I been running for how long on this too-thin wire". So put the wire in for max continual use. It's safer and will lead to less voltage drop which causes problems.

In my case, before I learned all this, I finally ended up with 1/0 wire (3 feet each leg) for my 12v 2000W inverter. Ran fine, cables never got very warm, but then again my loads 95% of the time were less than 100W. Were I running a 1500W space heater on it for hours (I didn't have much battery at the time to even attempt such a thing), and had I been using 4AWG, I would have most definitely been over-taxing the wire. Would it have led to a fire? Probably not, especially since the 4AWG would've been fused, but it's not good practice and *is* potentially dangerous. Electricity is no joke, especially at the high amps that 12V uses for larger loads. But had I not sold the inverter, I would've finally upgraded to 2/0.

 

[ricardocello]

Lithium iron polonium?

No thank you!