Charging 2 seperate house battery banks from alterntor?

[Dynamystic]

If your going to use a DC-DC charger back in the trailer you don't gotta go to 1/0 first of all, whatever supports the max load of the DC charger at those lengths is fine.. if you dont use a DC charger you petty much have to use ridiculous sized wiring despite the rather small loads because ANY significant voltage drop will prevent the remote bank from ever getting a full charge.. but a DC charger dont have that issue, if its getting 12.2V input, it can output 14.4V charge.

Chassis ground for this use should be fine, the alternator is using chassis ground anyhow.. however when adding new loads that are rather significant to a chassis ground I always suggest adding some redundancy to your engine ground straps.. this will give you more headroom for the extra load you added so no worries about burning up the OEM strap, and you get redundancy if one fails.. I had a grounding strap fail once on my old 75 Westy, just from age.. and it burnt up my throttle cable because that was the new path for ground.

Oh, you are right! I initially settled on 1/0 awg when I was planning to reuse my isolator and then never reconsidered the fact that the dc-dc charger would manage it all better. According to my chart here, even if I go as large as a 30a charger in the trailer I could get by with 4awg. I'm now contemplated putting the batteries in the back of the trailer for better weight distribution but even then it is only ~30' and 4 awg should suffice with that light of a max load. Does that sound right?

Also, when I did my infamous 6.0 powerstroke oil and egr coolers a while back I remember engine ground straps in a few locations. When you say adding extra redundancy, I'm curious if my rig would need it and if so how and where would you add them?

 

[dreadlocks]

sounds about right, also add in length of any ground wiring you might have..

usually when I'm doing a grounding upgrade on a vehicle I run a strap directly from the battery to a starter bolt, and then another strap from a bolt on the accessory frame to the chassis, but there's more than one way to skin a cat.. if yer confident you already got robust engine grounding then mebe its NBD.

 

[Dynamystic]

sounds about right, also add in length of any ground wiring you might have..

usually when I'm doing a grounding upgrade on a vehicle I run a strap directly from the battery to a starter bolt, and then another strap from a bolt on the accessory frame to the chassis, but there's more than one way to skin a cat.. if yer confident you already got robust engine grounding then mebe its NBD.

Confidence is not my strong suit when it comes to electrical, but hey, I'm learning. ;-)

Thanks again for the feedback!

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