Well. I have ordered my battery pak. It is 3/ 7k paks. So I will have 3 sets of cables to the bussbars. Magnum calls for #2 cable to inverter, 4400 hybird. So what yall think is needed from each battery pak to bussbars.

Do you mean 3, 7,000W battery packs?  I would trust this website's calculations over what someone told me on the internet. https://www.altestore.com/howto/wire-sizing-tool-for-12-24-and-48-volt-dc-systems-a106/

Edited October 6 by Ray,IN

Can't get that calculator to work on my cromebook or my android.

 I'm running W10 home version on a HP desktop, firefox 69.0.2 browser. I don't know what to say.

It's not really a calculator, as far as I can see. Here's the text:

STEP 1: Calculate the Following:

Looks like a max of 148 amps at 48 volts per pack

http://www.freesunpower.com/wire_calc.php#startGrn  

Calculator only goes to 100 amps, but pulling more than 100 amps from each bank is not likely. but would go one wire size bigger anyway.

Edited October 6 by jcussen

Glenn, If you're talking 7000 Watts at 48 Volts ???????? that's 145 Amps. You have three banks ??? Wooooooo Hooooooooooo. If a load was drawing 145  Amps and I was sizing the cable, Id opt for No 1 even if 2 suffices per Magnum (If the Blue Sea DC Systems chart is accurate ???? no guarantee) but, of course, that all depends on current and wire size and length and acceptable % drop, so I cant say from here exactly. If you have three such banks can I camp next to you and plug to your Inverter lol.

https://www.bluesea.com/resources/1437

Of course bigger wire = less line voltage drop and less I Squared R heat losses so bigger is better but the current and wire length are required to compute voltage drop. Its just in my DNA as an engineer to be on the conservative side and over engineer a bit, so if Magnum says No 2 Id still opt for No 1, still subject to actual current, wire length and acceptable % voltage drop 

John T    

Edited October 6 by oldjohnt

Length will be short. Building a wall in generator area. Batteries at door, two on floor, one above the other. Inverters, master box, solar controller, bussbars, disconnects, etc all go on this wall. I have some #2, plenty actually left over from my factory installed inverter. Not welding cable though. If not too hard to work will utilize it. On second thought, I will get #1. It is very short run and not costly. Or double up the #2?. Hate to throw it away

Edited October 6 by GlennWest

Also I realize that is a huge battery bank. But at the cost, why not. 

How are you charging this monster?

To begin with I will be purchasing 2 Magnums  MS4448PAE. IMarine has them for $1800 each. They will work as one master and other slave. They are each 60amp chargers. Will be purchasing the Magnum Panel also. Simplify wiring. I know everyone wants the Victon equipment now, but I am rather old school and simple.  I plan to eventually put solar on but no real rush on this.Get this up and running good and then solar. Solar be simple after all this. Weather is cooling off now and allowing me to do this. With my work it will be slow going though. I intend to do away with the subpanel and wire directly into breaker box. Need to do this in the short fall we have here. ACs be off while doing this. Don't want DW upset!!!! I considering getting a simple fast charger, guy getting batteries from has one for $150. Putting DC side online first. That is why I was asking about a DC/DC converter in my other post.

Edited October 6 by GlennWest

  On 10/6/2019 at 11:12 AM, Darryl&Rita said:

It's not really a calculator, as far as I can see. Here's the text:

STEP 1: Calculate the Following:

VDI = (AMPS x FEET)/(%VOLT DROP x VOLTAGE)

VDI = Voltage Drop Index (a reference number based on resistance of wire) FEET = ONE-WAY wiring distance (1 meter = 3.28 feet) %VOLT DROP = Your choice of acceptable voltage drop (example: use 3 for 3%) STEP 2: Determine Appropriate Wire Size from Chart Compare your calculate VDI with VDI in the chart to determine the closest wire size. Amps must not exceed the AMPACITY indicated for the wire size. Wire Size Area mm2 COPPER ALUMINUM AWG VDI Ampacity VDI Ampacity 16 1.31 1 10 Not Recommended 14 2.08 2 15 12 3.31 3 20 10 5.26 5 30 8 8.37 8 55 6 13.3 12 75 4 21.1 20 95 2 33.6 31 130 20 100 0 53.5 49 170 31 132 00 67.4 62 195 39 150 000 85.0 78 225 49 175 0000 107 99 260 62 205   Metric Size by cross-sectional area COPPER (VDI x 1.1 = mm2) ALUMINUM (VDI x 1.7 = mm2) Available Sizes: 1 1.5 2.5 4 6 10 16 25 35 50 70 95 120 mm2   EXAMPLE: 20 Amp load at 24V over a distance of 100 feet with 3% max. voltage drop VDI = (20x100)/(3x24) = 27.78 For copper wire, the nearest VDI=31. This indicates #2 AWG wire or 35mm2

I was clicking on link for easy caculator. I was making that hard. I just needed to look at amp rating for wire. 

Edited October 7 by GlennWest

I just have 3 of them.This pic vendor sent me.

deleted. 

Edited October 7 by GlennWest