Advice Needed: 48V Multi RS vs. 24V MultiPlus for Heavy-Duty Expedition Truck

DIY
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Hi everyone,

I am hoping to get some expert insight (and hopefully some manufacturer input!) to help break a tie regarding my system design.

I am currently building an off-grid expedition vehicle based on a massive 1977 MAN Kat 1 military truck. My electrical engineer designed a 48V system based strictly on this official Victron schematic: [Link: https://www.victronenergy.com/upload/documents/Manual-&-Drawing-Multi-RS-Solar-48-6000-Smart-LiFePO4-48V-200Ah-Lynx-Smart-BMS-Cerbo-GX-touch-70.pdf]

However, when I sent this design to several top-tier European Victron dealers for quotes, they strongly advised against it. They recommended a traditional 24V system with a separate MultiPlus and MPPT instead. As a layman, I’m caught in the middle and want to make sure I invest in the right architecture.

Context on our build:

  • Heavy 230V Loads: We are running standard household appliances, including a domestic fridge, air conditioning, air compressors, and a high-draw 230V jewelry heating furnace. We have virtually no native 12V/24V camper loads.

  • Isolated Systems: The truck’s 24V engine/alternator system will be strictly isolated from the house battery. We will use a DC-DC converter to safely charge the house bank from the alternator, so direct alternator charging of the lithium bank is not an issue.

The core disagreements we need help resolving:

1. Inductive Load Capability (Multi RS vs. MultiPlus) Because of our heavy 230V requirements (air conditioner compressors and the jewelry heating furnace), my engineer prefers the 48V Multi RS 48/6000 for efficiency and thinner cabling. Question: How does the Multi RS compare to a traditional low-frequency MultiPlus when it comes to starting heavy inductive loads and motor surges in a mobile environment?

2. Solar Architecture & Redundancy (All-in-One vs. Separates) The dealers warned against the Multi RS because if the integrated MPPT fails in a remote location, the whole inverter goes down. They also argued that the high-voltage solar string required for a 48V system will perform poorly due to partial shading on a vehicle roof. My engineer notes that to utilize the full power rating for a 6kW system, we will need high input voltages and series connections regardless of whether we use a 24V or 48V battery bank. Question: Does Victron support the Multi RS for this type of heavy off-road application, or is a separate 24V MultiPlus and MPPT genuinely the safer, more reliable standard here?

Any advice from installers who have built systems for heavy 230V expedition vehicles—or from Victron staff—would be hugely appreciated!

Thanks in advance for your help.

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They have the same surge capability.
Multi rs is great if you use a higher voltage battery bank.

24v bank can’t be used with a multi RS. So really the ‘house’ battery bank chosen will affect your choice at the end of the day.

For this carrying a spare is no big deal with weight being so light anyway. And it is simple to swap in when everything is labeled.

We have run trucks with high voltage strings. No issues to date. Usually when big power is needed you are parking the sun anyway because you need it all when there is a high draw.

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Agreed and I would add that alternator charging for the lithium house batteries is a big consideration. In the Victron ecosystem, by using a 24V house battery you can use Victron’s Orion XS 1400 as an efficient means of pulling power from the alternator. 24V-24V charging up to 1400W. I’m assuming, of course, that you have enough spare capacity on the alternator, so you’ll want to check that. If you lots of spare capacity you could consider using two XS 1400 chargers. If you’re going to be using this vehicle for extended periods in the back country, then the redundancy of alternator + solar is a good idea.

Victron does not (yet) have a 48V compatible Orion XS charger so alternator charging leads me to think that a 24V house bank is the better choice for you. However, you could instead add a 48V high-output secondary alternator on the engine and open up the possibility of having a 48V house bank with the dedicated 48V alternator. In the USA, the Arco Zeus alternator controller paired with their 48V high-output alternator is a great solution for a Victron system. I don’t if they are available in Europe, but surely someone makes something similar for the Euro market.

Good luck!