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eapatten asked

Wiring sizes for Victron Energy Orion-Tr Smart 12/12-Volt 30 amp 360-Watt DC-DC Charger, Isolated

Good morning,

I had a quick question regarding wiring gauge for the charger.

I am installing the charger in my travel trailer and on the input side (pickup truck) I am connecting it to my starter battery on my pickup truck (I have a 220A Alternator). FYI - I am not an electrician or mechanic and wanted to check what I am doing is safe and will work with the Charger.

With that the total cable run is 10-12 meters which according to the Victron manual is 16mm2 (6 AWG), however, other references call for 4 AWG. This is based on cable run length (10M), 40A max load at 12V. Will the Charger accept a 4 gauge (AWG) cable?

Please let me know if you have any questions. I have attached a diagram for your reference.

Thank you very much for your help.

Have a great day.

Best regards
Eric Patten

Truck Side Dc to DC Charging Diagram.pdf

orion-tr smartwiring
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2 Answers
rodneyab avatar image
rodneyab answered ·

@eapatten To answer only one part of your question, The charger terminals accept 6AWG. You can set up your long cable run from your starter battery with a much heavier cable, then step it down to 6AWG very close to the charger with 'power posts' terminals.

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eapatten avatar image eapatten commented ·

Thank you very much...


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Bob K avatar image
Bob K answered ·

Are you including the positive and negative conductor lengths to determine the total circuit length of 12 meters? That's necessary (a mistake I made when I installed the DC charger).

12m of 6 AWG wire has an ampacity of 50 amps with a 10% voltage drop, so it will safely carry the current but with some reduced voltage due to impedance. The 12|12-30 charger has an input voltage range of 10-17 volts. ~14v off the alternator minus 10% voltage drop means the DC charger's input voltage value will be 1.4v lower, or around 13v. If your alternator is too "smart" and reduces output down into the 12v range, this voltage drop could interfere with the DC charger's ability to output full current (since the Engine Shutdown Detection feature derates the charger's load as the input voltage drops). So yes, 6 AWG is safe but may prevent full charger output depending on how "smart" your alternator is.

dc-wire-selection-chartlg-1.jpg

If it's necessary to prevent this voltage drop, you'd need 2 AWG wire on a 12m circuit in order to keep voltage drop to just 3%. Why 2 AWG? The 12|12-30 charger is capable of outputting 40 amps for short periods of time and then derates as it heats up. I had to do this with my 2017 Tacoma because the "smart" alternator (which is completely controlled by the ECM in the 3rd Gen Tacomas) often hovers around 12.5v. A 10% voltage drop was causing the DC charger to derate too much. As Rodney said, you could run 2 AWG to the charger and then use single stud busbars to convert to 6 AWG, which is the maximum size the DC charger terminals will fit.

Yes, 4 AWG would be fine, too, to carry the persistent load of ~30 amps. 2 AWG would just be a touch more efficient.

dc-wire-selection-chartlg-2.jpg

1693260206736.png

Explorist.Life has a video explaining voltage drop with Victron DC chargers. The only flaw in the video is that Nate presumes you'll always have a higher voltage output from the alternator and therefore, the voltage drop isn't a problem, but if your "smart" alternator tends to output lower voltage, the voltage drop could indeed interfere with the charger's performance.

https://www.youtube.com/watch?v=0xOvINH4tKs


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