Thought I would post this, as it might be useful to some, now or in the future...
Having recently dived down the rabbit hole of changing our x2 110Ah Lead Acid batteries to a single 280Ah Lithium battery, what came next was certainly a learning curve...
NOTE: The image of everything in place, is before I have sorted and routed the cables properly (hence long loops), placed them all neatly into trunking (or I may use Tessa fabric loom tape if I can get it all neat enough), put the final VE terminations into ferrules and sorted the final locations for all the midi fuse holders (although the VE mega fuse is there along with new fuse at the starter battery for the B2B), so bear with me on that one.
Everything working as it should and is wirelessly networked together via Victron VE Direct, so that all the chargers (Solar, B2B and Mains) don't fight with each other (synchronised charging I believe they call it).
I left the Orion XS 50A B2B in its auto engine start/stop sensing state, rather than running in a D+ signal to it (as I don't have a smart alternator). So far "touch wood" it has not turned itself on when it shouldn't. In fact I'm quite impressed as I can see it does turn itself on within 30 seconds of starting the engine, and off again within 10 seconds of turning the engine off.
Outside of the Victron kit, I had to send my main control board to Apuljack who professionally disabled the factory split charge system, as the relay is PCB mounted and controls other elements such as auto step retraction, D+ signal to fridge etc etc which I still wanted to maintain.
Along with that, coupled with some advice from Apuljack, I removed the factory mains charger (as it was only capable of charging lead acid batteries) and replaced it with a Victron 20A charger, which now only charges the leisure battery (as if it remained switchable to the starter battery, I would have to faff about changing its charge profile to Lead Acid and back again etc).
For those that are interested (info from ApulJack) if you have a Nord control unit, your charger will have x3 outputs, a positive, a negative and a smaller 12V signal wire. That signal wire just puts the "lightning bolt" symbol on your display panel to show you are on mains hookup and is also responsible for telling the system that the charger is on, so that it can auto-switch the charge between hab and cab batteries (which you do not want in a Lithium & Lead Acid battery setup), so without that signal present, it will never do anything you don't want it to.
I don't mind not having a little symbol there telling me I am on mains, I ought to know if I am, as I would have physically plugged it in myself lol.
As there is no longer any EHU or solar charge going to the starter battery - I fitted a VanBitz Battery Master, which is now responsible for keeping the starter battery topped up from the leisure battery. As lithium has a different state of charge voltage graph to lead acid, I know that the starter battery will almost always have at least 12.9v in it, even if I were to completely drain the lithium. The stereo in the dash now runs from the leisure battery, (with an ACC switch on the dash), so we can listen to the radio or have sound from the TV through the speakers inside without worrying about a flat starter battery too. Will keep an eye on it though, as worst case, I can fit a small separate Lead Acid EHU/mains charger dedicated to the starter battery only, when I would have to switch the B2B charger out of its auto sensing state and onto a D+ signal too.
Ended up fitting separate charger and inverter, rather than a Multiplus inverter charger, mainly due to the space I have available where I wanted everything, plus cost, as I got a great deal on them both separately.
Wife can now use her hair straighteners off-grid lol, coupled with Victron Inverter remote control switch inside - Currently only supplying it's own single dedicated socket for just one item at a time (lots of info on that on the web, but Victron confirm that you are protected if it is only supplying a single socket and using only one item at once). That means I didn't have to fit a new mains consumer unit at this stage. In the future I might look to install a changeover switch, so that it can switch it to powering all the existing sockets in the MH, but then that's a whole new ball game in terms of consumer unit protection where no actual earth exists, so will see how we get on - It's only circa 850W, so can't imagine needing to use more than one thing at a time on it anyway.
Aside from final cable tidying and fusing, plus swapping the old 90W solar panel for a larger 400W panel on the roof (where I am not looking forward to un-bonding the old panel grrr), I am happy with the way everything is working so far.
Having recently dived down the rabbit hole of changing our x2 110Ah Lead Acid batteries to a single 280Ah Lithium battery, what came next was certainly a learning curve...
NOTE: The image of everything in place, is before I have sorted and routed the cables properly (hence long loops), placed them all neatly into trunking (or I may use Tessa fabric loom tape if I can get it all neat enough), put the final VE terminations into ferrules and sorted the final locations for all the midi fuse holders (although the VE mega fuse is there along with new fuse at the starter battery for the B2B), so bear with me on that one.
Everything working as it should and is wirelessly networked together via Victron VE Direct, so that all the chargers (Solar, B2B and Mains) don't fight with each other (synchronised charging I believe they call it).
I left the Orion XS 50A B2B in its auto engine start/stop sensing state, rather than running in a D+ signal to it (as I don't have a smart alternator). So far "touch wood" it has not turned itself on when it shouldn't. In fact I'm quite impressed as I can see it does turn itself on within 30 seconds of starting the engine, and off again within 10 seconds of turning the engine off.
Outside of the Victron kit, I had to send my main control board to Apuljack who professionally disabled the factory split charge system, as the relay is PCB mounted and controls other elements such as auto step retraction, D+ signal to fridge etc etc which I still wanted to maintain.
Along with that, coupled with some advice from Apuljack, I removed the factory mains charger (as it was only capable of charging lead acid batteries) and replaced it with a Victron 20A charger, which now only charges the leisure battery (as if it remained switchable to the starter battery, I would have to faff about changing its charge profile to Lead Acid and back again etc).
For those that are interested (info from ApulJack) if you have a Nord control unit, your charger will have x3 outputs, a positive, a negative and a smaller 12V signal wire. That signal wire just puts the "lightning bolt" symbol on your display panel to show you are on mains hookup and is also responsible for telling the system that the charger is on, so that it can auto-switch the charge between hab and cab batteries (which you do not want in a Lithium & Lead Acid battery setup), so without that signal present, it will never do anything you don't want it to.
I don't mind not having a little symbol there telling me I am on mains, I ought to know if I am, as I would have physically plugged it in myself lol.
As there is no longer any EHU or solar charge going to the starter battery - I fitted a VanBitz Battery Master, which is now responsible for keeping the starter battery topped up from the leisure battery. As lithium has a different state of charge voltage graph to lead acid, I know that the starter battery will almost always have at least 12.9v in it, even if I were to completely drain the lithium. The stereo in the dash now runs from the leisure battery, (with an ACC switch on the dash), so we can listen to the radio or have sound from the TV through the speakers inside without worrying about a flat starter battery too. Will keep an eye on it though, as worst case, I can fit a small separate Lead Acid EHU/mains charger dedicated to the starter battery only, when I would have to switch the B2B charger out of its auto sensing state and onto a D+ signal too.
Ended up fitting separate charger and inverter, rather than a Multiplus inverter charger, mainly due to the space I have available where I wanted everything, plus cost, as I got a great deal on them both separately.
Wife can now use her hair straighteners off-grid lol, coupled with Victron Inverter remote control switch inside - Currently only supplying it's own single dedicated socket for just one item at a time (lots of info on that on the web, but Victron confirm that you are protected if it is only supplying a single socket and using only one item at once). That means I didn't have to fit a new mains consumer unit at this stage. In the future I might look to install a changeover switch, so that it can switch it to powering all the existing sockets in the MH, but then that's a whole new ball game in terms of consumer unit protection where no actual earth exists, so will see how we get on - It's only circa 850W, so can't imagine needing to use more than one thing at a time on it anyway.
Aside from final cable tidying and fusing, plus swapping the old 90W solar panel for a larger 400W panel on the roof (where I am not looking forward to un-bonding the old panel grrr), I am happy with the way everything is working so far.
, that needs tidying up a tad for me. It's in a locker that's very rarely opened though - So long as it's neat, there are no cable chafing points & it's correctly protected, then I am happy.
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