Having difficulties figuring things out

[Cdelmage]

Hi - with all the info available that I have reviewed, I am still unsure what size breaker to use.

I have an RV and recently purchased a Renogy 2000w (4000w peak) pure sine inverter for use when boondocking. Overall, I won't be using it that much. It will feed one 120v outlet in the kitchen area. I plan to use it for my small 1500w kettle and 700w microwave (short reheating use). Nothing that requires more wattage.

I have two deep discharge 12v marine batteries in parallel. The inverter will be 2 feet away. I currently have 4AWG wires to connect the batteries and inverter.

What breaker size to buy and install inline?

Thanks in advance.

 

[Al D]

Drawing 1500W from a 12V battery bank will pull at least 125A from those batteries. Assuming you're using copper wire, your 4AWG wire will probably only support up to 95A with the proper jacket. The inverter will have some efficiency loss (it will probably take another 10% from the battery current draw) so you're probably going to pull close to 140A from your batteries.

You're not ready for breakers yet because the wires aren't sized properly. You could upgrade your wires or put your batteries in series. If you put them in series, you have to be sure the inverter (and, not mentioned, charge controller) can handle 24V nominal.

If the batteries are in series, no need for a breaker between the two batteries. The connection between the battery bank and the inverter should be sized 25% more than your wire's amperage rating. The 4AWG copper THHN wire you can get at the hardware store can safely carry up to 95A. So 25% more would have you finding a 125A DC breaker.

If you upgraded your wires, you would find out the amperage rating and multiply by 1.25, rounding to the nearest DC breaker size.

If you want to put a breaker after the DC-AC conversion, you could use a standard 15A household AC breaker for the appliances.

I'm not an electrician so you should verify this information with the appropriate authorities.

 

[Cdelmage]

Thanks a lot. This detail is very helpful as well. I now think I have what I need.