Battery Cable Parallel Sizing

[kmacdonald]

Originally Posted by Frankly

Don't know exactly what you have in mind, but the only legit reason I can imagine for 4/0 cable is a bow thruster or big inverter a long way from the batteries. I like robust 12V distribution design but not crazy. 660 AH in Cbreeze but nothing bigger than #1 except I did use 1/0 for the bow thruster and inverter.

Get you a piece of 4/0 and try bending it in a medium loop.


Frankly

I am a big fan of collective bus arrangement (+ & -) and an isolation switch on each battery.

Yes. I was going to say the same thing but bit my tongue. 4/0 is soooooo overkill i'd be ashamed if I didn't say something and my tongue was hurting. 4 AWG is fine for what you want and 2 AWG would be the absolute MAX you should consider. Go find some 4/0 and you'll see what we mean. It is incredible stiff. Overkill beyond comprehension. The interconnect between 2V cells in a 12V battery are equivalent to 6 AWG. My conscience is clear now.

I don't like the isolation switch idea because of the extra connections needed and the ease of removing a battery anyway.

Wire each positive to a power post or high capacity bussbar. Do the same for the negative. There's your balance.

[kmacdonald]

Originally Posted by sailorboy1

Saving $60 by using 2/0 cables over the 4/0 just seems silly to me concerning the $2k battery cost. My cable to my the battery switch is 4/0 and fused for that.

That 4/0 cable carries 4 times the current as the interconnect cables if connected the way I said above.

[kmacdonald]

Hint: engineered cable size will be different for different wiring schemes. If you throw Hail Marys overkill it.

[sailorboy1]

Originally Posted by kmacdonald

That 4/0 cable carries 4 times the current as the interconnect cables if connected the way I said above.

it only carris 4 times the current of the far interconnect cable

you seem very ganist the 4/0 cable, tell be a technical reason not to use it

[sailorboy1]

Originally Posted by a64pilot

I’m leaning toward 0000 myself, as it’s going to about 4 ft to the inverter, and you can’t be too big, just too small.
Regardless of distance the Manual for my MS2812 recommends 4/0
It can pull 250 amps after all, I don’t but I have occasionally left the water heater on and not realized it when I turned on the inverter and tripped the 200 amp breaker I have it on.

your L16s are going to be in series, you pretty much have to use the 4/0 or solid bar

[kmacdonald]

Originally Posted by sailorboy1

it only carris 4 times the current of the far interconnect cable

you seem very ganist the 4/0 cable, tell be a technical reason not to use it

Not technical but: Expensive, too stiff, weight (I know a few pounds wont hurt but it really will if you do that with everything)

Technical reason for connecting the way we said above: balance because each cable carries 1/4 load current

Run the 4/0 cable from the power post or buss bar to the load. (only if your load and distance requires it)

[kmacdonald]

Originally Posted by sailorboy1

it only carris 4 times the current of the far interconnect cable

you seem very ganist the 4/0 cable, tell be a technical reason not to use it

The batteries are individually connected to a power post or buss bar so all the batteries to buss bar cables carry the same current. The load cable carries 4 time the current of each battery to buss bar cable. Balanced.
You are right to balance the install, don't blow it on the details.

[sailorboy1]

Originally Posted by kmacdonald

Not technical but: Expensive, too stiff, weight (I know a few pounds wont hurt but it really will if you do that with everything)

$34.28 more - not expensive for something that will last forever
stiff - so what, it doesn't have to snake around anything
weight -come on be real, 6 x 8" cables and 2 x 2' cables

[kmacdonald]

Originally Posted by sailorboy1

$34.28 more - not expensive for something that will last forever
stiff - so what, it doesn't have to snake around anything
weight -come on be real, 6 x 8" cables and 2 x 2' cables

OK, do it for the technical reason then.

Keep the cables to the power post or buss bar the same length.

[sailorboy1]

Originally Posted by sailorboy1

Is it worth it to try to "balance" the cable size of

My thought process was all messed up when I wrote this. I have no problem needing "fixing" and am 100% good to go.

[kmacdonald]

If you chose to connect the batteries the traditional way where the batteries are set side by side with the positive terminal oriented the same way and you connect the load positive and negative to opposite ends of the battery bank it will still be balanced but the interconnects will carry the full load current and require larger cables.

[kmacdonald]

Originally Posted by sailorboy1

My thought process was all messed up when I wrote this. I have no problem needing "fixing" and am 100% good to go.

Debatable?

[kmacdonald]

Originally Posted by sailorboy1

My thought process was all messed up when I wrote this.

That's OK. It happens to everyone on occasion. That's why peer review is so useful.

[sailorboy1]

Originally Posted by kmacdonald

Debatable?

No matter what I write about or how I write it, lots here think I am an idiot. So who can tell since I am really just a fat man living in his parents basement in Ohio.

[kmacdonald]

Originally Posted by sailorboy1

No matter what I write about or how I write it, lots here think I am an idiot. So who can tell since I am really just a fat man living in his parents basement in Ohio.

Well I don't think you're an idiot. You know how important a balanced configuration is and I'm pretty sure most here don't know it or believe it. I do think everyone knows you are out cruising AND enjoying life your way.