I am updgrading the system I built in my RV 5 years ago, I want to replace the 30A Orion for an Orion XS. As you can see on the picture, the negative of the starter battery is grounded to the chassis and two 10mm2 cables (brown and red) go from the starter battery to the Orion for about 3m total distance.
The Orion XS has only one connection for the negative (the Orion 30A has 2 negatives IN and OUT). How do I connect ?
Also I know 10mm2 is going to be light for 50A current intensity but I would like not to change for 16mm2 and redo everything.
You are all good. The Orion XS is non isolated and you are in an RV with a shared chassis ground. This means you can ground the Orion directly to the chassis and the starting and house batteries will share the ground. To utilize what you have already as simply as possible I would do something like run both grounds that formerly when into the Orion 30A to a terminal stud of some kind along with a new ground for the Orion XS. You just want to make sure it is all grounded to chassis sufficiently and you are fine.
(2) 10mm2 wires will be totally fine for the 50A Orion.
On the ground side from the Orion I would go ahead and use the 16mm2.
As a note. If both your batteries are already sufficiently grounded to chassis you can just ground your Orion XS directly to chassis with 16mm2 if that is easier.
Also, dont forget to make sure both sides are fused near the batteries. 60 amps is good.
Thanks for the reply. For what I understood, I need to buy a negative Bus Bar, and connect it to the Shunt with all my loads minus on it, including both 10mm2 negatives cables that formerly went into the Orion 30A (INPUT negative and OUTPUT negative) and a new 16mm2 cable for the GND connexion on the new Orion XS.
The only ground chassis connexion I would have, would be the original connexion from the negative of the starter battery (its at bottom right on the installation first pic).
For the cable sizing, if I have measured once again and I have a bit more than what I thought, meaning 4m total length (positive cable + negative cable) from the starter battery to the Orion 30A in 10mm2.
Here are 2 differents test for Voltage Drop Calculations , the one from the Victron Toolkit app says 7% Voltage drop .
Specific resistance of a wire not only depends on its length and diameter/cross section but also on its temperature. The victron toolkit specifies 60°C but no specific resistance value, where as the website does vice versa, it uses 0.0182ohm/mm2/m but does not specify a temperature.
The length you enter into the toolkit app is cable length. I know the help page on the top right isnt very useful either, but in general a cable consists of two, or more, conductors (yes technically theres also single core cables, the difference there would be the double isolation compared to a wire). So what you enter into both the website and the toolkit app is the distance between the two devices, not the round trip length of the individual conductors. The website is clearer on this.
If you enter 2m into the toolkit app you also get roughly 3%, which is on the edge for 50A, but you dont charge at 50A all day long. 0.4V of voltage drop at 50A is 20W, or 5W/m. The wire will get warm, but should not be an issue by itself. Rather make sure that all your connection points are good, no bad crimps, no loose bolts or corroded fuse
Go 16mm2 for your run from the bus bar to the starting battery. If its simpler just go 16mm2 from the bus to a nearby chassis ground.
That single 10mm2 on the positive side is a problem. I thought you originally said you had (2) 10mm2 positive cables from the starting battery to the Orion. You definitely need to go bigger than a single 10mm2. Either (2) 10mm2 or a single 16mm2 will be fine.
. Whats your POV on this ?
