bennetimo
New Member
- Joined
- Jul 30, 2021
- Messages
- 15
I'm upgrading a Victron Orion 12/12-30 (isolated) charger to the new Orion XS 50A (non-isolated) in a campervan. My house system in the van centers around a Victron Lynx distributor as the main hub, and that is grounded to the chassis. As such I was using the isolated charger in a non-isolated way.
So for the original setup I had positive and negative wires from the starter battery to the input of the orion, and positive and negative out to the lynx and ultimately to the batteries. This has worked great with no issues at all but I am now upgrading to the much better XS. There is no isolated model available to do a direct swapout so I'm wiring it very similar to how explorist.life does it here: https://shop.explorist.life/shop/all-products/victron-orion-xs-12-12-50-dc-to-dc-charger-retrofit-wiring-kit/ . i.e. using the original cables, but with the two negatives combined at a junction stud and then a third new cable added to connect to the single GND terminal on the Orion. All works and I'm getting close to the full 50A rated output from the new XS. Happy days!
However despite having dedicated wires for both the positive and negative cable from starter battery to the orion, there is very little current using the dedicated return negative path. I have an amp clamp and measure only ~2A passing back along the negative wire run (16mm² over perhaps 5-6m), with the remaining ~48A instead using the chassis return path from the lynx. Therefore as it stands the dedicated negative wire to the starter battery is doing virtually nothing. The chassis ground from the lynx is connected via a large 70mm² cable to a bolted point on the metal stripped of paint so is a decent ground, but I was surprised how little current is using the dedicated wire. Most things I've read (and in sterling/renogy manuals) suggest the chassis is often a poor return path and recommend a direct path. I have double checked the ring terminal crimps etc on the negative wire and can't see any issues.
Am I missing something here, or when wiring a non-isolated DC charger would you always expect the majority of current to flow through the chassis despite having dedicated wires, making them somewhat redundant? The chassis is steel, much less conductive than copper, but with a much bigger mass so...
. With the old setup using the isolated charger, there was never any normal current flow in the ground wire from the lynx. I would prefer to keep it that way.
Also the excellent 'Grounding Made Simpler' by Filter Guy (thanks, great resource) says of non-isolated DC-DC chargers:
Would welcome any thoughts!
So for the original setup I had positive and negative wires from the starter battery to the input of the orion, and positive and negative out to the lynx and ultimately to the batteries. This has worked great with no issues at all but I am now upgrading to the much better XS. There is no isolated model available to do a direct swapout so I'm wiring it very similar to how explorist.life does it here: https://shop.explorist.life/shop/all-products/victron-orion-xs-12-12-50-dc-to-dc-charger-retrofit-wiring-kit/ . i.e. using the original cables, but with the two negatives combined at a junction stud and then a third new cable added to connect to the single GND terminal on the Orion. All works and I'm getting close to the full 50A rated output from the new XS. Happy days!
However despite having dedicated wires for both the positive and negative cable from starter battery to the orion, there is very little current using the dedicated return negative path. I have an amp clamp and measure only ~2A passing back along the negative wire run (16mm² over perhaps 5-6m), with the remaining ~48A instead using the chassis return path from the lynx. Therefore as it stands the dedicated negative wire to the starter battery is doing virtually nothing. The chassis ground from the lynx is connected via a large 70mm² cable to a bolted point on the metal stripped of paint so is a decent ground, but I was surprised how little current is using the dedicated wire. Most things I've read (and in sterling/renogy manuals) suggest the chassis is often a poor return path and recommend a direct path. I have double checked the ring terminal crimps etc on the negative wire and can't see any issues.
Am I missing something here, or when wiring a non-isolated DC charger would you always expect the majority of current to flow through the chassis despite having dedicated wires, making them somewhat redundant? The chassis is steel, much less conductive than copper, but with a much bigger mass so...

Also the excellent 'Grounding Made Simpler' by Filter Guy (thanks, great resource) says of non-isolated DC-DC chargers:
Since switching to the non-isolated charger presumably there is also now a ground loop, as current can flow back both through the chassis as well as via the dedicated negative wire. Are there issues with this setup other than potential RFI noise? Lots of wiring diagrams I've seen share a similar setup to mine (dedicated negative wire between batteries and orion, as well as a chassis ground), e.g. https://shop.explorist.life/wp-cont...fe-EXPLORE-50A-MOTORHOME-WIRING-DIAGRAM-1.png , so presumably would all exhibit a similar thing.Since the tie between House Battery DC Negative and ground should only be done in one place, the DC-DC charger becomes the bonding point to chassis and the Jumper between the DC negative Bus and the ground bus is removed. Otherwise, a ground loop would be created and possibly create RFI issues.
Would welcome any thoughts!