I want to confirm my understanding of cable size requirements, specifically in relation to my caravan to tow vehicle connection.
I’m putting together a victron-based system for my van (12v 400AH battery, solar inputs, multiplus inverter). I have an orion XS 12/12 50A battery charger that I intend to connect to the tow vehicle.
The total one-way cable run from charger to vehicle alternator will be close to 10m. Using the Victron App for a cable length of 10m (assuming it requires the one-way distance) gives 70mm2 conductor size (Awg 00). Increase that to AWG 000 if I should be entering the total circuit distance. That’s a lot of copper and will require some large Anderson Plugs!
Yes, you are understanding that correctly. Long DC runs unfortunately need lots of copper.
My cable calculator indicates you could get away with AWG 0 on a 20m circuit, but that’s at a 2.75% voltage drop which is very less than ideal, AWG 00 would put it at 2.18% voltage drop, AWG 000 would be 1.73% voltage drop. Obviously the less voltage drop the better, but there’s some wiggle room at least.
Also, note that you’re not connecting the Orion XS to the alternator, you’re connecting it to the start battery - that may change things for the better or for the worse depending on where the start battery is relative to the alternator.
Not much difference between battery and alternator location.
I’ve noted that I can scale back the max charge on the Orion. I bought 50A thinking it would give me more wiggle room, without understanding the cable size implications. I could live with 30A.
BTW how would you connect AWG00 to those relatively small connection points on the Orion?
You’d typically step it to a smaller gauge when it gets close to the unit, via dual busbars or PowerPosts or something similar so that you can transition to a gauge that can fit into the terminals. Since the larger gauge isn’t a matter of ampacity but only to combat voltage drop, no harm in using the large gauge for the length of the run and then just transitioning to a smaller gauge once you get close to it.
You should check out the BLUETTI Charger 1. I helped a mate install one in his Ford Ranger. It’s a universal MPPT charger. You put 12V-24V in and get up to 56V out. We put a 100/50 MPPT on the battery and ran the 56V cable down to the back. This reduced the cable size from 32mm to 4mm. The MPPT outputs the full 560W. An excellent product if you have a long cable run. The app is nice as well.
A related question. In my current van, the connection from the vehicle to the caravan is managed by a LV Automotive microprocessor controlled battery separator (140A). My understanding is that this device disconnects the van battery when the vehicle battery drops below a voltage threshold. Would you recommend I use this device with my new setup, or bypass it and manage the connection by setting voltage thresholds in the Orion XS?
Unfortunately as I’m wholly unfamiliar with your van, its wiring, the operation/logic of the systems already in place, and the possible effects of bypassing the existing systems (or not), I wouldn’t offer any opinion on that. I’d suggest consulting with a reputable installer who’s familiar with your OEM systems prior to proceeding just to make sure you’re not going to cause issues within the existing electrical system.
You could use it to send a remote signal to Orion XS. Connect the output 12V signal to the H terminal and turn the Orion on. You could also use it for the Bluetti Charger 1 if you dont get the desired performance and function from the Orion.