question

guy-planner avatar image
guy-planner asked

MultiplusII wire sizing

Hello;

I am in the process of converting my 5th wheel camper to solar (2021 GrandDesign Reflection 240RL). I need help selecting the correct wire gauge bt my batteries and MultiPlusII (see my attached diagram, .. the writing in red are areas that I need help with). My Victron MultiPlusII manual indicates AWG 1/0 up to 5m (16 feet) and AWG 2/0 up to 10m (32 feet). However my solar supplier and several other youtubers indicate AWG 4/0. My batteries and MuliPlus will sit beside each other, so less than 10feet cabling will be used (likely closer to 5feet). I also need help with correct size ground cable to MultiPlus.

Any help is appreciated.

Guy

My Wiring Schematic vs 3.pdf

Multiplus-II
my-wiring-schematic-vs-3.pdf (8.6 MiB)
2 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

kevgermany avatar image kevgermany ♦♦ commented ·

Which multiplus is it?

0 Likes 0 ·
guy-planner avatar image guy-planner kevgermany ♦♦ commented ·
It is the MultiPlus II, see diagram included (PDF)
0 Likes 0 ·
2 Answers
Sarah avatar image
Sarah answered ·

Assuming you have a 3KVA multiplus (as per your diagram) a 4/0 cable would be overkill. I would recommend a) following the recommendations in the manual and b) if in doubt go for the larger 2/0 cable. At 12 v the voltage drop at 200 amps using 2/0 would be approx .4 volts. Take a look at the Victron cable calc app.

Also if you have a Cerbo in the config and can connect it to the internet you should not need the MK3 USB interface as you can do software updates and configuration via VRM.

4 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

kevgermany avatar image kevgermany ♦♦ commented ·
The multiplus control widget has been removed. So the MK3 interface is probably still needed.
0 Likes 0 ·
guy-planner avatar image guy-planner commented ·
re; MK3 USB, I was debating if I should get this, thank you for your suggestion.

Also, do you have experience using "double cables" ? .. using 2x AWG 1/0 ?

0 Likes 0 ·
kevgermany avatar image kevgermany ♦♦ guy-planner commented ·
Sorry, no double cable knowledge.
0 Likes 0 ·
guy-planner avatar image guy-planner commented ·
Hi Sarah; thank you for your reply (sorry for delay, I am new to this forum). Does Victron have a cable calc web page ? I could not find a Victron cable calc app (I would prefer web page, but can't find either).
0 Likes 0 ·
jamesmcclatchey avatar image
jamesmcclatchey answered ·

I have a Multiplus II 3 KVA 2x120 V. The manual recommends two 1/0 cables for the DC input. Two 1/0 cables has a higher ampacity than a single 4/0. This may be overkill, but I like following instructions. The main downside is that takes making twice as many lug connections. On the other hand, it may be easier to bend 1/0 cable around corners than 4/0. Top of page 11.

https://www.victronenergy.com/upload/documents/MultiPlus-II_12V-24V_3kVA_2x120V/MultiPlus-II___Quattro-II_120V-230V-en.pdf


2 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

guy-planner avatar image guy-planner commented ·
Hi James;

I read the "2x positive and 2x negative cables", but I assumed it meant 1 cable each for positive and negative. If I understand you correctly, Victron would have me run 2 positive cables (parallel) from MultiPlus to my batteries, and also same for negative cables ? I have never seen this set up. Can you point me to any illustrations of an installed system with double cabling ?

0 Likes 0 ·
Al avatar image Al guy-planner commented ·

Hi @Guy Planner I used dual cables for our 8KVa Quattro install. It's fairly common, but cables must be equal length. I also made sure they have the same current path length on the busbars by mounting either side of the main T connections. It's a bit messy when the photos were taken, but hopefully shows how I did it.

img-20210325-1802034.jpg

img-20210326-130118.jpg

img-20210331-1851572.jpg

flir-20220105t115608.jpg


0 Likes 0 ·
img-20210325-1802034.jpg (3.2 MiB)
img-20210331-1851572.jpg (2.8 MiB)
flir-20220105t115608.jpg (1.9 MiB)
img-20210326-130118.jpg (1.7 MiB)