wire conductor size question to avoid overheating cables

[WorldwideDave]

12V 200 Ah bus bars span 2 cells in series, 4 in parallel. GFB 100Ah cells
I think this is saying that the battery post size is M6.
So here's my question...
I want to use as large a conductor from the battery post to the T-class fuse for positive and over to the victron shunt for negative.
I think the correct lug would be a 1/4 SAE size Selterm or equivalent lug.
I see Selterm sells a AWG 6. non-affiliate link to amazon US page with it:

https://a.co/d/fpuClas

Ancor sells one 'marine grade' up to 1/0 AWG:

https://a.co/d/7OVcLPa

I only need to run 2 feet lengths of both.

while running 150 A to 200 A consistent with my pool pump setup is highly uncommon except for the tests I'm performing on the BMS, right now the only thing getting warm in my setup are the conductors in this location between the battery cells and the t-class fuse and the shunt.

The wire selection chart here:

http://assets.bluesea.com/files/resources/newsletter/images/DC_wire_selection_chartlg.jpg

suggests that I should be running 1 AWG (150A) to 2/0 AWG (200A) conductors..
1/0 is larger than 1 AWG, but not as large as 2/0 AWG.
I think - may be wrong - that 1/0 is commonly called 0 AWG?

AI tells me:

Copper wire
At 75°C, 1/0 copper wire can carry 150 amps with insulation types like THHN/THWN-2 and RHW
At 90°C, 1/0 copper wire can carry 170 amps with insulation types like XHHW-2 or USE

Battery cable
1/0 battery cable can carry up to 250 amps

Is that accurate?

The wire I was looking at is a favorite here - the windy nation welding wire:

https://a.co/d/2rZfStb

Though to be honest I don't see an amperage or current rating except up to 600V. The close up pictures they provide are for 4 AWG cables, not the 1/0.

battery spec sheet below/attached.

 

[HRTKD]

I don't see the distance the cables will run. Amps, volts and distance are all required.

 

[robbob2112]

1/0 and 0 are the same .. just like 00 is 2/0 and 000 is 3/0

If you want your wires to run cool you look them up on a 60c chart as if they are going inside walls ... i.e. standard NEC chart... then buy 105c battery/welding wires .... they won't even get warm to the touch in most cases....

the cross-sectional area or circular mills determine the capacity via the resistance per thousand feet.... resistance time current^2 is the watts produced.... the trick is you want the wires to dissipate the heat as fast as it is generated.. and length plays into it two ways along with size... Shorter is lower resistance so less heat build up... larger size has more copper mass to absorb the heat so if the current isn't constant it will take longer to level off at equilibrium. Large size and longer means the cables have enough mass to loose the heat as fast as it is generated so they are always at room temp in free air.


So, 4/0 will never even get warm at 200amps - but realize it is way overkill

Post in thread 'Robbob2112 Answer thread'

Dec 8, 2024

Seems like I am always looking these up to answer questions

NEC Ampacity table
Wire ampacity tables -- original PDFs attached where possible






Windy Nation ampacity table for welding wire - NOT UL listed





DLO cable - fine stranded - UL listed




abyc cable chart attached

• robbob2112

• 

 

[WorldwideDave]

I don't see the distance the cables will run. Amps, volts and distance are all required.

See above in original post?
Line one - 12V
Line eight - 2 feet.
Line ten - 150 or 200. Prefer thick as possible but finding the lug to fit a 1/4 is difficult in that size.

 

[WorldwideDave]

1/0 and 0 are the same .. just like 00 is 2/0 and 000 is 3/0

If you want your wires to run cool you look them up on a 60c chart as if they are going inside walls ... i.e. standard NEC chart... then buy 105c battery/welding wires .... they won't even get warm to the touch in most cases....

the cross-sectional area or circular mills determine the capacity via the resistance per thousand feet.... resistance time current^2 is the watts produced.... the trick is you want the wires to dissipate the heat as fast as it is generated.. and length plays into it two ways along with size... Shorter is lower resistance so less heat build up... larger size has more copper mass to absorb the heat so if the current isn't constant it will take longer to level off at equilibrium. Large size and longer means the cables have enough mass to loose the heat as fast as it is generated so they are always at room temp in free air.


So, 4/0 will never even get warm at 200amps - but realize it is way overkill

Post in thread 'Robbob2112 Answer thread'

Dec 8, 2024

Seems like I am always looking these up to answer questions

NEC Ampacity table
Wire ampacity tables -- original PDFs attached where possible






Windy Nation ampacity table for welding wire - NOT UL listed





DLO cable - fine stranded - UL listed




abyc cable chart attached

• robbob2112

• 

yes I like over and above. Doesn't have to be 4/0 or 0000 wire. bigger issue is finding the 1/4" lug in conductors that size.

 

[HRTKD]

See above in original post?
Line one - 12V
Line eight - 2 feet.
Line ten - 150 or 200. Prefer thick as possible but finding the lug to fit a 1/4 is difficult in that size.

You write so much that the necessary details get lost. Seriously, write less. Long posts don't get read.



4/0 is way overkill. The ampacity charts have an implied length of cable. Your length is so short that the charts will tell you to use too large of a size for your situation. Use a calculator instead.

 

[robbob2112]

Uhm, no problem at all... zorro.com

 

[WorldwideDave]

You write so much that the necessary details get lost. Seriously, write less. Long posts don't get read.

View attachment 277728

4/0 is way overkill. The ampacity charts have an implied length of cable. Your length is so short that the charts will tell you to use too large of a size for your situation. Use a calculator instead.

your calculator says to use 2/0.
I'm saying that I cannot find a 1/4" lug for 2/0.
Hence the post.
I will make shorter posts, boss. Just more detail oriented and don't like a lot of back and forth questions. Always struggled with short emails too.

 

[WorldwideDave]

Uhm, no problem at all... zorro.com

What the what?

 

[WorldwideDave]

1/0 and 0 are the same .. just like 00 is 2/0 and 000 is 3/0

If you want your wires to run cool you look them up on a 60c chart as if they are going inside walls ... i.e. standard NEC chart... then buy 105c battery/welding wires .... they won't even get warm to the touch in most cases....

the cross-sectional area or circular mills determine the capacity via the resistance per thousand feet.... resistance time current^2 is the watts produced.... the trick is you want the wires to dissipate the heat as fast as it is generated.. and length plays into it two ways along with size... Shorter is lower resistance so less heat build up... larger size has more copper mass to absorb the heat so if the current isn't constant it will take longer to level off at equilibrium. Large size and longer means the cables have enough mass to loose the heat as fast as it is generated so they are always at room temp in free air.


So, 4/0 will never even get warm at 200amps - but realize it is way overkill

Post in thread 'Robbob2112 Answer thread'

Dec 8, 2024

Seems like I am always looking these up to answer questions

NEC Ampacity table
Wire ampacity tables -- original PDFs attached where possible






Windy Nation ampacity table for welding wire - NOT UL listed





DLO cable - fine stranded - UL listed




abyc cable chart attached

• robbob2112

• 

Appears the windy city wire specs you found (thanks!) state that their AWG 2 will handle over 200 A, but the 1/0 and 2/0 are well over 200 A.

So windy city for the 1/0 wire, and ancor for the 1/4" lug to fit on 1/0 wire and I should be good to go?
Saw the non-UL listed about the wire. Happy to pay more for better wire on amazon, but has to be for sale on amazon, thanks.

 

[HRTKD]

I buy 1/4" 2/0 lugs from TEMCoIndustrial.com. They work great!

Tin Plated Copper Ring Terminal - 2/0 AWG, 1/4" Hole (25 Pack)

TEMCo Tinned Copper - marine grade battery cable ends are made from 99.91% annealed tinned pure copper (Lead and Mercury FREE), providing a high degree of conductivity for maximum current flow and designed with a heavy-duty construction for high temperature durability and enhanced mechanical...

temcoindustrial.com

 

[robbob2112]

Ok, http://zoro.com

 

[WorldwideDave]

I buy 1/4" 2/0 lugs from TEMCoIndustrial.com. They work great!

Tin Plated Copper Ring Terminal - 2/0 AWG, 1/4" Hole (25 Pack)

TEMCo Tinned Copper - marine grade battery cable ends are made from 99.91% annealed tinned pure copper (Lead and Mercury FREE), providing a high degree of conductivity for maximum current flow and designed with a heavy-duty construction for high temperature durability and enhanced mechanical...

temcoindustrial.com

Love the company.
Found many options on amazon for them. Good call!

Amazon.com

 

[HRTKD]

Ok, http://zoro.com

What's an "R" between friends?

 

[HRTKD]

Love the company.
Found many options on amazon for them. Good call!

Amazon.com

Sometimes it's out of stock on Amazon but in stock on their website. Their shipping cost from their website isn't bad. They ship USPS.

 

[robbob2112]

What's an "R" between friends?

Apparently he intended me to find out at the point of a sword

 

[LRocker]

your calculator says to use 2/0.
{snip}

His calculator does not say that. It says "0% - 3% is excellent" and that even 2 awg (much thinner than 2/0) is barely over 1% loss.
That part on the right is the legend, independent of the calculations.

 

[740GLE]

I was able to snag selterm m6 1/4 lugs for 2/0.

https://a.co/d/icjOtkF

Just go with 2/0. For 12v systems you need as much conductor as you can afford.

 

[WorldwideDave]

I was able to snag selterm m6 1/4 lugs for 2/0.

https://a.co/d/icjOtkF

Just go with 2/0. For 12v systems you need as much conductor as you can afford.

Can you share a link to what wire you bought on amazon please? I have lugs coming soon.

 

[740GLE]

2/0 Gauge Pure Copper Ultra Flexible Welding & Battery Cable

WindyNation's Power-Flex welding and battery cable is a highly flexible industrial-grade electrical cable. A high strand cable count combined with a soft, pliable EPDM insulation results in a flexible cable every time. Our cable is resistant to tears, cuts, abrasion, water moisture, and...

www.windynation.com

Order direct from them

 

[WorldwideDave]

Th

2/0 Gauge Pure Copper Ultra Flexible Welding & Battery Cable

WindyNation's Power-Flex welding and battery cable is a highly flexible industrial-grade electrical cable. A high strand cable count combined with a soft, pliable EPDM insulation results in a flexible cable every time. Our cable is resistant to tears, cuts, abrasion, water moisture, and...

www.windynation.com

Order direct from them

Thanks. Bought on Amazon. $55 for twice as long. Can cut in half and use for multiple setups. So I will have 2/0 with 1/4 lugs.

 

[740GLE]

Ummmm

Im seeing 10ft red and 10ft black for $98.11 from windy nation website, free shipping. They also offer a $15 off first order discount.

From windy nations storefront on Amazon it’s listed at $105.97 for the same order.

Bowing down to Amazon one click payment isn’t all that’s cracked up to be.

 

[Drizzt321]

For major wiring & lugs and the like, I avoid Amazon for the plague. Often it's OK, as described, but too much possibility of CCA or other crap bundled in. Since it's close shipping is fast, I buy from McMaster-Carr for major wiring/lugs. In my skimming some some other non-Amazon links, those are all probably good recommendations too.

I'll second welding wire. Very tough, extremely flexible (easier to fit through turns & such). Just make sure to properly crimp them. Or buy pre-crimped from a good site in the lengths you need, that's what I did for my recent 2/0 when I upgraded my battery/fuse/etc system.

 

[WorldwideDave]

I use welding wire. All good.
I have bought lugs from many places. Wires as well.
I find that amazon, selling Selterm and others like Windy Nation, seem to have what I need. And yes, one click to buy is great even if I pay a few bucks more every once in a while.

 

[robbob2112]

I actually have decided I like the lugs and wire from Temco the best followed closely by Selterm.... There are other places that sell wire... batterycableusa and wire and cable your way

And, I have decided I don't really like the Windy Nation wire that much anymore --- I bought black and red 20ft lengths in several sizes -- one is all twisted up where they wound it around their length bobbin... 3 of the others have discolorations that run the length of the wire where the paper liner was overlapped

I'll still use it because it is to expensive to toss, but I am not thrilled and I won't be buying more from them.