Inverter and Shunt

[Soundsailor]

For my 3,000-watt inverter, I'm using a 4|0 cable and a 300 Amp fuse. My 4 batteries can each supply 100 Amps. They are tied together by a bus bar. My theoretical max draw by the inverter is slightly over 300 Amps but I doubt if I'll ever hit that with my current setup. As others have said, don't undersize your system, you may regret it.

[Jomani]

The conversion factor from 12v DC to 120v AC is not 1:1. Between the voltage drop in the 12v circuit (higher with smaller cable) and the inevitable power loss in the conversion process, I think you would be hard pressed to achieve 90% efficiency. If you can achieve 90% efficiency, it will take 3300 watts (275 Amps) of DC power to realize 3000 watts of AC power.

If you decide to create a separate inverter circuit by keeping the existing bus bar/positive cable, and running a second positive cable from the battery to the inverter via fuse and switch, the negative cable (from battery to shunt) will still have to accommodate the entire DC load (inverter plus refrigerator plus DC panel load) because you have to run all of the DC load through the shunt. From shunt to inverter, you could get by with a smaller cable as long as you also go from shunt to frame ground to cover all of the other DC loads.

[huntindog]

Thanks. I think that helps. I have 1/0 cable, a 300 amp inline fuse, and battery disconnect switch to wire inline. My cable runs will be less than 2'. I figured I'd have to go direct to the battery and skip the buss bar. I have 3 x 100AH batteries. I'll upgrade all the battery cables to 1/0 as they're all #6 or #4 now. While it is 3000 watt, I'll probably never actually use 1/2 of the capacity.

Looks like you are referring to the factory buss bar? It will not handle the inverter. FWIW, I have buss bars that will handle the inverter, so I do it that way,

[more tired since retired]

Quote Originally Posted by CaptD103 View Post
Thanks. I think that helps. I have 1/0 cable, a 300 amp inline fuse, and battery disconnect switch to wire inline. My cable runs will be less than 2'. I figured I'd have to go direct to the battery and skip the buss bar. I have 3 x 100AH batteries. I'll upgrade all the battery cables to 1/0 as they're all #6 or #4 now. While it is 3000 watt, I'll probably never actually use 1/2 of the capacity.

If you use your air conditioning and any other AC device is is on, you will be over 50% of that 3000 amps. Microwave uses minimum of 1000 watts.

[Redapple63]

Thanks. I think that helps. I have 1/0 cable, a 300 amp inline fuse, and battery disconnect switch to wire inline. My cable runs will be less than 2'. I figured I'd have to go direct to the battery and skip the buss bar. I have 3 x 100AH batteries. I'll upgrade all the battery cables to 1/0 as they're all #6 or #4 now. While it is 3000 watt, I'll probably never actually use 1/2 of the capacity.

I highly recommend the buss bar approach. I am using three different buss bars.

I am using the Pike Industries pos and neg buss bars to tie the batteries together, then to the Victron Linx Distributor. This is a fused buss bar rated to 1000 amps. From that Victron Distributor to each of the loads. So in essence you would send one set of wires to your current unfused buss bar for those loads. Another set to your converter through either a new cutoff switch or the existing one, and yet another for solar and inverter.

I hope this helps.

Bill