Hi,
I live in the Netherlands, and I want to set up a 3-phase system. I am planning to order the following:
- 3x Multiplus II 5000
- Victron Lynx distributor or fuse holder
- Victron Cerbo GX
- Victron GX Touch 50
- 2x Basen Green with 16 EVE 314Ah batteries
I have a few questions about this setup:
- Is the Victron Lynx distributor just an expensive fuse holder, or does it offer additional functionality? Can I replace it with a standard fuse holder to save on costs?
- There’s a Victron GX and a Victron GX MK2. Will firmware support for the standard GX last as long as for the new MK2?
- Where should I buy fuses for the Victron Lynx distributor? I can find them on AliExpress, but I’m hesitant to buy safety components from there.
- The batteries will be connected to the Victron Lynx distributor, which has a fuse for each battery. What should the fuse rating be? Each battery is 314Ah in a 16S1P configuration, so the max current would be 0.5 * 314 = 157A. Therefore, a 160A fuse should suffice for each battery. Is that correct?
- In a 3-phase system, I noticed that all battery + and - terminals are connected together and lead to the busbar of the Victron Lynx distributor. How should I connect them safely? I’d prefer not to use a “Power In” busbar since it’s quite expensive.
- Do the Multiplus battery connections also need fuses? What happens if a battery connection on the Multiplus shorts out? Could that damage other Multiplus units on the battery input/output? Which connections need fuses, and what values would you recommend?
- The batteries can deliver 1C in total (2 * 0.5C), so that’s 320A. The 3 Multiplus devices can each charge or discharge at a maximum of 70A, so the total charge current would be 210A, right? What should the cable diameter be for connecting to the battery racks? Would 0 AWG or 2 AWG be appropriate?
The person I’m installing this for also asked about connecting MPPTs. He has 23 solar panels of 600W each and wanted to connect the solar panels directly to the batteries via MPPTs. I advised against this for the following reasons:
- Solar panels with MPPTs put a lot of strain on the batteries. I aim to avoid using the lower and upper 10% of the LFP batteries’ capacity. If MPPTs are used in summer, the batteries will likely always be at 100% SoC.
- All the power would pass through the batteries, leading to more frequent cycling and faster wear.
- If we get penalized for sending excess power to the grid in summer and the batteries are at 100% SoC, all the power would need to be redirected to the mains. Can an MPPT disconnect automatically to handle this?
- Since you already have the Multiplus devices, why not wait? MPPTs can always be added later if needed.
- Adding MPPTs is costly.
- While there’s a minor power loss from DC->AC and AC->DC conversions, you get more control without MPPTs because the battery and solar connections are separate.
Additionally, he wants to connect as much of his household power as possible to the emergency outputs of the Multiplus units, except for the heat pump. I strongly advised against connecting almost everything to the emergency outputs. Here’s why:
- All connected devices’ power passes through the Multiplus systems. Victron does a great job, but there will always be some power loss. If most devices are connected to the emergency outputs, there will be noticeable losses over a year.
Any suggestions or feedback would be greatly appreciated. Thanks in advance!
Best regards,
Mark