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mike-howard avatar image
mike-howard asked

Correct wire type and guage

Hey guys I am installing a Orion 30 amp non-isolated dc/dc charger in my camper. There is an existing red wire which used to charge my battery and runs from the engine compartment of the vehicle back to the house battery which is now a lithium 300 amp hour.

Can I use the same red wire that's already running along the chassis of my car or do I need one with many more threads as I was reading online that more threads makes a better connection. And by threads I mean small wires wrapped within the larger wire if that makes sense. Photo attached.

1000067828.jpg

Related question how important is it to properly torque down these wires into the dc/dc charger as I don't have a screwdriver that measures torque can I just hand tighten it pretty strongly?

wiring
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5 Answers
Justin Cook avatar image
Justin Cook answered ·

Do not use that wire; besides being the wrong type it's also far too small - use the appropriate wire gauge and type for the round-trip circuit length (you'll most likely end up at 6AWG or thicker, depending on your vehicle) as is explicitly detailed in the installation manual: https://www.victronenergy.com/media/pg/Orion-Tr_Smart_DC-DC_Charger_-_Non-Isolated/en/installation.html

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Alexandra avatar image Alexandra ♦ commented ·

Very important to properly torque (tightening pretty strongly is fairly close). But it is more important to use the correct fine stand cable.

It is also important to periodically check the connections. So maintenance is essential. They get hot and connections get loose over time.

You can't properly torque the wire you are showing there. It also does not fill the clamp correctly and can cause burning. Twisting them together like that makes the problem worse. Even though it is very convenient when installing ;)

It will get hot.

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mike-howard avatar image
mike-howard answered ·

Thank you guys so much for the answers and help. I am thinking about getting this 8 guage wire that looks quite good. The run from my engine to the Camper battery is 18 feet. You like this cable: https://amzn.to/48hLpGe

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kevgermany avatar image kevgermany ♦♦ commented ·
Use one of the online calculations to work out cable size. Aim for a voltage drop of less than 3%. Remember to calculate for the round trip, 36ft not single trip. 8 guage is clearly inadequate.
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lee-taylor avatar image lee-taylor commented ·

I would not use aluminium wire for this. I would try searching for a welding supplier. If it were me I would use something like 16mm2 wire to minimise voltage drop. The OFC stuff was popular with HiFi people and is ok for hooking up your speakers but not for this. Realistically the best option will be what a welder uses. Or something like this maybe? https://www.amazon.com/Welding-Battery-Flexible-Inverter-WindyNation/dp/B013DJJXNE/ref=sr_1_12?crid=3J7LEHW9DBL98&keywords=3%2F0%2Bwelding%2Bcable&qid=1708269261&sprefix=3%2F0%2Bwelding%2Bcable%2Caps%2C322&sr=8-12-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9tdGY&th=1

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mike-howard avatar image
mike-howard answered ·

I have been to every store I can think of:

Home Depot
Lowes
ACE Hardware
Las Vegas City Electric
Autozone
and about 5 others....

and NO ONE seems to have this 120+ threaded copper wire in 4 or 6 gauge (do you guys think I am good running 30 amps the 25 feet from my car battery back to the Victron DC/DC converter with 6 amp, or should I go 4 amp to keep temps even lower?)

Can anyone send a link to the product you recommend I buy on Amazon.com?
This one seems to have the required threading and dimensions...anyone dig (or hate) this one?

https://amzn.to/3HZ51Ey (some folks are saying this is copper clad aluminum, and not pure copper. does that matter?)

Option #2: https://amzn.to/49eRg0k (some folks also say this is not pure copper. If I was going to use a bit of the extra as a grounding wire, does it need to be pure copper?)

Option #3: https://amzn.to/3OJM7oI (looks like oxygen free. worth the 300% price increase?)

Option #4: https://amzn.to/3T2i528 (100% OFC, half the price of option #3. you dig?)

Thanks so much guys!
Mike

p.s. Side question. Do I need to run this directly to my car battery?

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kevgermany avatar image kevgermany ♦♦ commented ·
Aluminium matters. It's perfectly suitable but has lower current ratings than copper.

Better to use a proper cable supplier rather than Amazon if you're unsure.


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mike-howard avatar image
mike-howard answered ·

ok team, i think i found the solution. Do you all like this one for the installation? I found this: https://amzn.to/3yndO1n

WNI 4 Gauge 30 Feet Red 4 AWG Ultra Flexible Welding Battery Copper Cable Wire - Made In The USA - Car, Inverter, RV, Solar

  • 100% Made in the USA cable. Ultra-flexible, SAE J1127 approved, PURE copper cable manufactured and annealed to ASTM standards.
  • Please see the photo gallery for a detailed specification chart.
  • Rated up to 600 volts, operating temperature: -58°F to +221°F, flexible, solvent repellent, abrasion resistant EPDM insulation.
  • WindyNation Power-Flex welding/battery cable is a premium grade, PURE copper cable manufactured to the highest standards right here in the USA!
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mike-howard avatar image mike-howard commented ·
Do we like this choice of wire team?
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mike-howard avatar image
mike-howard answered ·

related question. if the cable run length from my engine to the back of the camper is 22 feet (with all the snakes and turns under the rig). But I heard some folks mention round-trip length. The red wire running back there from the previous (low voltage setup) is just one strand, not a round trip. so do i need 25 feet of cable, or do i need to run this in round trip for some reason?

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Justin Cook avatar image Justin Cook ♦♦ commented ·

DC (to over-simplify things) travels in a circle, so "round-trip length" is calculated when calculating a DC circuit. If you're using a non-isolated DC-DC charger, presumably you're using the chassis as your negative return, but the round-trip circuit length will still be ~44' if your positive run is ~22'; thus when using 4AWG wire in a 44' round-trip circuit length at 12v carrying roughly 38A to the DC-DC charger, you'll suffer a roughly 3.75% voltage drop between the start battery and the charger's input. Definitely not great, but fortunately the charger can compensate for that fairly well.

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