question

Jeff Stichler avatar image
Jeff Stichler asked

MultiPlus 2x120/12/3000 Marine Install Planning Questions

I'm planning the install of a MultiPlus II 2x120 inverter/charger into my boat. My shore connection is 120/240 50A and also have an onboard 12KW generator that is also 120/240 50A. The only loads on the boat that are 240V are the three air conditioning units. These 240V loads are fed from their own secondary shore/generator/off selector switch. I have been following the Victron install schematic as it is the closest to my application.

https://www.victronenergy.com/upload/documents/MultiPlus-II-3KW-2x120VAC-12VDC-400Ah-Li-Lynx-Smart-BMS-Cerbo-GX-touch-generator-MPPT-Orion-Tr-Smarts.pdf

I have a few questions/clarifications regarding this install...

1) The Victron schematic above shows that AC Out1 is/can provide No Break loads for 240V out which MultiPlus II manual says that is not possible? Can anyone explain the contradiction here? Is the schematic incorrect?

2) My plan was to only use the MultiPlus to power the 120V loads fed from the first shore/generator/off selector switch. I was going to run the output of that first selector switch to a new 3 pole 50A breaker then to the AC Input on the Mulitplus II and then AC Output 1 back to the panel to the 120V side master breaker. Does anyone see a problem with this plan?

3) I was planning to leave the second shore/generator/off selector providing the 204V as is without running any of it through the inverter. Am I missing something here? Does/should this run through that selector switch to AC Out 2 back to the 240V loads? Seems unecessary to me.

4) The single input/dual output cutoff/battery switch from the Lynx Distributor running to the inverter on the positive...does anyone have a part number/source for that switch they are using? I have found single input/output and dual input/output switches but not the combo.

Thanks and looking forward to the replies.


Multiplus-II
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.

1 Answer
dc-marine avatar image
dc-marine answered ·

Hi,

The following reply assume you’re in a North America setting.


1. AC OUT 1 should be the no-break output. AC OUT 2 should only be active when AC IN is present.


2. Depending on your loads and usage of the first panel, you may want to consider the PowerAssist feature which can add another 25a of current to your 50a AC input. If you think your total usage could exceed 50a, I would wire the output of the Multiplus with 4awg cable and a 80a 3P breaker as to be able to fully use the PowerAssist feature. If not, then 6awg with a 50a 3P breaker will do.


3. You can leave the second panel alone, but you won’t be able to read the total current draw from your loads as the Multi will only record what is fed through. On the other hand, it allows you to power the second panel using the gen while on shore power for the first panel, which would be fine. If you’re able to deal with managing the total load by yourself so you don’t trip your shore power, you could set the input current limit lower to allow room for the second panel loads while on shore power or generator.


4. The switches you’re referring to are Blue Sea System HD-Series switch part number 3000 and E-Series 5510e. They are simple on/off and on/off double pole switches. The diagram shows the 3000 which has one input stud and two common output studs (they show the grey 3000 switch as a e-series though). They do this because of using a single 4/0awg input split into two parallel runs of 2/0awg output to help with voltage drop. ABYC E-11 doesn’t alllow this unless each conductor is protected by a suitable over current protection device such as fuse or breaker. So you would want a single 4/0awg with a 400a fuse through a regular on/off switch such as the Blue Sea System M-Series 6006, or you would need to fuse each of the two 2/0awg output wires with 200a fuses after the 3000 switch. European standards are different than North America in some applications.


5. Don’t forget that the case ground must be no smaller than 50% of the main conductor of no less than 1 gauge smaller. Meaning 3/0awg for a 4/0awg or a 4/0awg for a double 2/0awg feed. This is also an ABYC E-11 standard for installation onboard a boat and it must be connected back to the main battery, main negative bus or engine block (if using common negative for all systems).


6. Your main DC negative bus should be bonded to the main AC ground bus using at least the same size conductor as your biggest AC conductor (probably 6awg in your case).


Have fun !

12 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.

Jeff Stichler avatar image Jeff Stichler commented ·

Thank you for the information dc-marine, it is very helpful. I am in North America so yes the ABYC would be the standards I want to follow. I have some follow up questions to your reply if you don't mind.


1. The manual states just as you did above and I'm not questioning that...it just was the Victron schematic I referenced that shows you should/could also wire up a 240V MCB to feed 240V no-break loads. I feel like Victron should take this off the schematic as it leads to confusion. Did you notice that on the schematic?


2. I don't really need PowerAssist at this time so that is why I planned to go with the 50A MCB. Will 4AWG fit into the MultiPlus II AC OUT1 terminal block? If it does it may be best to wire it this way just in case PowerAssist is needed in the future. Thanks for bringing that up.

3. I'm not totally sure why the boat was wired with two SHORE/OFF/GEN selectors. Shore power is one 125/250 50A shore power input. Somewhere, behind cabinetry I presume, they have paralleled shore power to provide two sets of L1-L2-N to feed each of the SHORE/OFF/GEN selectors. The 12KW generator is wired the same way as shore power and should theoretically be able to provide the same 50A to both L1 and L2 so I don't know why they would need the second selector. As you pointed out, I guess I could leave that second selector alone, but I think it would also be nice to to capture the current from those 240V air conditioning loads with the inverter for a total picture. To do this I guess I would just remove the outputs of that second selector from the circuit and feed the 240V MCB from AC OUT2.

4. Thanks for the information on the switches. I am using the Lynx distributor so I guess I would like to use the fusing there instead of adding two more fuses to step down the wire size. With that in mind I guess there would be two options? 1st option run two 2/0awg positives from the Lynx using 200A fuses on each lead to the dual circuit battery switch and on to the MultiPlus II. 2nd option would be run 4/0awg with 400A fuse from Lynx to single circuit battery switch and continue with 4/0awg to the MultiPlus II. The total run from the Lynx to the MultiPlus II is probably 18" so I don't think there would be appreciable voltage drop on the 4/0awg? Victron recommends the two 2/0 so maybe that is the best way to go? What is your opinion on this?

5. Seems like the case ground is supposed to be the same size as the DC negative...maybe this was a fairly recent change to the ABYC regarding this? I was planning to use 4/0awg from case ground back to the Lynx ground.

6. I believe this is the case but I'm going to hunt that down and make sure it exists!


Thanks again for your help and hopefully you can find a bit of time to answer the follow ups questions.

Cheers!

0 Likes 0 ·
Show more comments