Welding wire - pushing substantial DC amps, sanity check

[dcg9381]

So, I'm driving a set of DC to AC inverters with a set of Lithium batteries. I have two places to view amperage and they both "agree" within about 10%. I'm pushing 165A continuous (55A * 3 batteries), my cables (both) are getting "warm" to the touch, not hot, I can keep my hands on them, and seem to hold temp for the hour or so I ran this test. Cables are hand pressure crimped with copper, 3/8 terminals, they are not hot at the connectors.

I don't typically like to see/feel "warm" wires. Thoughts?


Battery specs:

• 48V * 3 batteries
• LiFePO
• 100A peak sustained discharge (they have individual 100A breakers)
• 5120 Wh capacity

Cable specs:

• Copper "DC Welding Wire" 4/0 AWG (4 feet)
• Copper "DC Welding Wire" 2/0 AWG (6 feet)
• Ends are hand crimped, copper

Welding cable amp charts should I'm "well" within spec. I realize welders do not run 100% cycle. I also find differences between charts for welding cable and "universal wiring (DC)". Below.

 

[wyliesdiesels]

WAG- the sizing charts are based on welder duty cycle and non-continuous/intermittent use.

 

[PCustoms]

Got a diagram how this is all wired?

What voltage are you running?

What is the actual amperage per wire?

The *3 in your description is throwing me off....

Edit:

What brand cable?

 

[Walkers]

Probably should measure the twmp. As long as you are not exceeding 90*C you are probably fine.

 

[Lightning rod]

The definition for ampacity is the continuous current that can flow in a conductor with respect to rated ambient and temperature rise so I suspect the chart is for continuous current.
I don't know what the Universal chart is telling us. I would disregard
The welding cable chart looks in line with what I used in the lab for long term experiments

If the cable is marked 90 degC , the rating is usually 55 degC rise over a 20 degC ambient for a total of 75 degC total temp

If you are running 165a , assuming the rating from the chart is 550a continuous, temp rise = (165/550)^2 x 55 = 5 degC +20 degC = 25 degC
Maybe even up to 30 degC total
So, I would say warm , not HOT.
Have an infrared heat gun to check ?

You have lots of margin in this setup.
How did you hand crimp ? Hydraulic tool , crimping tool , hammer punch crimper ?

Any of these will work if properly used.

In conclusion. You are good. Don't worry.

 

[dcg9381]

Got a diagram how this is all wired?

What voltage are you running?

50-52V DC input. Lithinum "48V" batteries.

Input side I'm measuring about 8.5Kw DC.
Output measuring 7.7Kw AC.

What is the actual amperage per wire?

The wires in the photo (2/0 and 4/0) are passing 165A (measured in two places) into the inverters.

The *3 in your description is throwing me off....

Sorry, that's how you "build" DC cables. Hammer punch crimp. (first time doing that)

Edit:

What brand cable?

https://www.amazon.com/gp/product/B01MD1YL1I/?tag=atomicindus08-20

The definition for ampacity is the continuous current that can flow in a conductor with respect to rated ambient and temperature rise so I suspect the chart is for continuous current.
I don't know what the Universal chart is telling us. I would disregard
The welding cable chart looks in line with what I used in the lab for long term experiments

If you are running 165a , assuming the rating from the chart is 550a continuous, temp rise = (165/550)^2 x 55 = 5 degC +20 degC = 25 degC
Maybe even up to 30 degC total
So, I would say warm , not HOT.
Have an infrared heat gun to check ?

Yes, I have an IR temp gauge. I just tore this down off the "bench", so it'll be a bit before I can re-test it. I'd say 85-90F, "warm" to the touch. Easy to keep your hand on it. I ran it for an hour.

I'm largely asking because I may need to push this up to 225A @ 50V DC (we'll use 4/0 wire everywhere).

You have lots of margin in this setup.
How did you hand crimp ? Hydraulic tool , crimping tool , hammer punch crimper ?
Any of these will work if properly used.
In conclusion. You are good. Don't worry.

Hammer punch crimper.

 

[PCustoms]

If it's hot at the crimp only then you have a bad crimp.

Otherwise I would not use no-name brand wire in an application like this.

 

[Lightning rod]

If it's hot at the crimp only then you have a bad crimp.

Otherwise I would not use no-name brand wire in an application like this.

The amazon product description says the product is made in the USA

Welding Cable

WindyNation welding battery cable is a high-quality pure copper flexible cable manufactured in the USA! Sold in 4/0, 2/0, 1/0, 2, 4, 6, and 8 Gauge lengths ranging from 5 to 400 Feet, and black/red insulation. Bundle and save! Purchase welding battery cable with 10 pieces of cable lugs and 3...

www.windynation.com

also their website says the same

 

[PCustoms]

The amazon product description says the product is made in the USA

Welding Cable

WindyNation welding battery cable is a high-quality pure copper flexible cable manufactured in the USA! Sold in 4/0, 2/0, 1/0, 2, 4, 6, and 8 Gauge lengths ranging from 5 to 400 Feet, and black/red insulation. Bundle and save! Purchase welding battery cable with 10 pieces of cable lugs and 3...

www.windynation.com

also their website says the same

Hate to break it to you, but made in the USA doesn't mean it isn't complete ****.

This has the SAE spec on it but no UL code. Maybe it's legit, but I still stick to "name brand" wire when it matters.

Anchor marine tinned wire is pricy but from what I've seen is well worth the money.

 

[nadogail]

Welding Loads are not steady, but intermittent, and if your leads remain cool enough to handle with your bare hands IMHO you are good.