DC/DC Battery Charger Wiring Size

[Jeffrey207]

Hello all, I need help figuring out my wiring size for my Orion DC/DC 12/24v-15a battery charger. This is my plan: 12v Van battery --> Orion 12v/24v-15a charger --> my 24v fuse block which is connected to my ‘house battery’. My van battery is a lot easier to access then my alternator, so that why I've chosen to wire it there.

Q - How do I figure out the wire size on the input side of the charger? Is it simply based off of how much power is being pulled, which is 15a? If this is the case, do I size the wire for a 30a load on the input side, since this side is 12v?

Thank you in advance!

 

[MisterSandals]

Is it simply based off of how much power is being pulled, which is 15a?

If it charges 24V at 15A...
28V charging x 15A = 420W

The draw on the input, and adding 15% conversation loss (use real number if you have it):

420W / 10V cutoff / .85 efficiency = 49.4A

 

[Jeffrey207]

Man, that's perfect. Thanks for putting those calculations together, super helpful.
Can I use that same calculation for the output side?

28V charging x 15A = 420W

The real efficiency is 88%

420W / 20V cutoff / .88 efficiency = 23.8A
The output voltage range is 20v-30v

 

[MisterSandals]

420W / 20V cutoff / .88 efficiency = 23.8A

The cutoff is when the source is too low. I guessed 10V.
420W /10V /.88 = 47.7A on the input side.

 

[time2roll]

Page 7 of the manual says 6 to 16 mm2 depending on length. Either way 60 amp fuse.

Manual

 

[Jeffrey207]

Ahh yess, thank you! I'll go off of what it recommends in the manual.