Wire gauge from vehicle battery to DC to DC converter

[gfmucci]

I have a DC to DC, 12 to 48 volt 10 amp converter that I would like to feed from a 12-volt battery in my car (engine running). What is the gauge of the cable I should use to feed that converter from the battery? It will be drawing 40 amps. The converter will feed the input of an Ecoflow Delta @480 watts. Before I send the 14 gauge cable I (mistakenly?) ordered back to Amazon which I suspect is too thin, should I use at least a 10 gauge cable? The length of this cable from the battery to the converter will be less than 6'. Here is a link to what I think answered my question, but I would appreciate confirmation:

12 Volt Wiring: Wire Gauge to Amps – Offroaders.com provides information and entertainment to 4×4 enthusiasts worldwide

www.offroaders.com

 

[Samsonite801]

Here is a voltage drop calculator I like to use. Then I usually like to go a gauge size larger just for fun. Make sure to size the fuse or breaker to protect the wire from overcurrent or short.

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

 

[gfmucci]

Thanks. I'm going with 8 gauge.

 

[Alphacarina]

Thanks. I'm going with 8 gauge.

That sounds way too small??

Using the calculator in the link above, 12 volts DC, 40 amps 5 foot long cable, the wire size calculator says . . . . 3 gauge

Don

 

[gfmucci]

That sounds way too small??

Using the calculator in the link above, 12 volts DC, 40 amps 5 foot long cable, the wire size calculator says . . . . 3 gauge

Don

Not how I read it.

 

[Samsonite801]

That sounds way too small??

Using the calculator in the link above, 12 volts DC, 40 amps 5 foot long cable, the wire size calculator says . . . . 3 gauge

Don

Actually the calculator just defaults on the 3 AWG when you open the page. The answers always shows green no matter what. It is really just a voltage drop calculator. You can input any parameters and it shows you how much voltage drop and if that is acceptable to you then you can use that.

I usually just plug in different gauges on the calculator and move to larger size until I've killed most of the voltage drop, and the benefit starts diminishing... But the user makes the judgement, it's like length, gauge, to cost and benefit.

 

[Alphacarina]

Actually the calculator just defaults on the 3 AWG when you open the page. The answers always shows green no matter what. It is really just a voltage drop calculator. You can input any parameters and it shows you how much voltage drop and if that is acceptable to you then you can use that.

Ahh . . . . I see that now - It's not designed to be a 'wire gauge calculator'. IMO, it should have an option to just default to a 3% drop and give you . . . . the wire gauge you need - What a novel idea!

Don

 

[HRTKD]

Using my preferred wire gauge calculator, I confirmed that 8 awg should work.

Interactive Wire Size Calculator

Battery Chargers, Inverters, Solar Components, and Wiring Supplies for Boats, RVs, and Off-Grid Applications.

baymarinesupply.com

 

[Mdsd]

Hey shouldn’t one be able to just run a cable to the DC2Dc charger from the starter battery, and JUST run a shorter cable to the chassis for the ground, instead of running one back to the starter battery (even that uses a chassis ground)
- I am asking because I see some people do that.
- why not? And why if it should be.