Multiplus 2 System Issue

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charlie-77 asked May 29 2024 at 9:29 AM

Multiplus 2 System Issue

Hi everyone, I’m a complete newbie to victron and have recently taken on a customer that wants us to look after their solar vans, part of a contract with the new solar install. They have an issue with one of them and cant seem to get the system to switch on. They have a multiplus 2 inverter connected to 4 batteries and using the cerbo gx and lynx distributor. All batteries are fully charged and if I try and connect via the app I can only connect to the batteries and mppt, should I be able to connect to the Cerbo unit too?

Just need to know where to start to try and identify what’s not working, I feel like it could be a communication issue. The cerbo appears to have no lights on although power is connected is this correct? Is there a procedure I can follow to see what equipment isn’t working. I’ve added pictures of the kit so hopefully you guys can help me out. Thanks

setup connection issue fault

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Answer 1 · 2024-05-29T11:24:07Z

Paul B answered · May 29 2024 at 11:24 AM

on the cerbo the wifi light should be on if its powered. from the picture the cerbo is not powered as the power cable looks like its unplugged.

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Answer 2 · 2024-05-29T12:21:31Z

Rob Fijn answered · May 29 2024 at 12:21 PM

In this case there are Victron lithium Batteries. The MP-II should 'see' the VE.BMS via the VE.bus, if not.. the MP-II will not switch ON. Maybe replace this cable.
On the VE.BMS the negative (black ) wire is not needed, as the negative comes via the VE.bus. Take this wire off.
This should work without the Cerbo GX.
Hope this helps a bit. Let us know how this goes.
Rob

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charlie-77 commented · May 29 2024 at 9:36 PM

Thanks, yes so 4 lithium batteries installed, when you say replace the cable do you mean the rj45? The MP-II doesn’t connect directly to the ve bus, it’s plugged into the cerbo then a rj45 from the cerbo to the ve bus. Would this suggest a fault with the cerbo? If I was to connect the MP-II directly to the ve bus do you reckon it would start communicating properly?

One thing I forgot to mention as well, the screen that’s connected to the cerbo is also blank so indicating no power.

As it stands there is a rj45 from the MP-II the mppt and the ve bus all connected into the cerbo.

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delf67 charlie-77 commented · May 30 2024 at 7:03 PM

Try connecting the RJ45 from the ve.bus BMS directly to the Multiplus rather than going via the Cerbo. Does it turn on now?

Also remove the black lead from the BMS as described by Rob above.

The screen gets it's power from the Cerbo, so you would expect it to be off if the Cerbo is dead.

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charlie-77 delf67 commented · May 31 2024 at 8:24 AM

I’ve tried the multiplus connected directly to the ve bus and still nothing. I’m going to say there’s an issue with the cerbo for definite but it’s just whether there’s something else going on as well

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delf67 charlie-77 commented · May 31 2024 at 9:42 AM

As Rob said above, the Cerbo is not essential to the system. If it doesn't work with the Multiplus connected directly to the BMS , then yes there is something else going on.

Are you getting battery voltage on the input terminals of the Multiplus? I'm thinking it may be a BMS issue.

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charlie-77 delf67 commented · May 31 2024 at 12:07 PM

Yes voltage on the battery terminals, I tried plugging the multiplus directly to the ve bus with a couple of different cables, just incase, but still nothing. Could there be an issue with the inverter too?

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delf67 charlie-77 commented · May 31 2024 at 12:39 PM

It sounds like there could be. It should switch on with just the Multiplus and the BMS without the Cerbo. I would probably try to unplug the RJ45 from the multiplus and try it stand-alone. If you've definitely got 48V @ the inputs and it still doesn't switch on, then that would confirm an inverter issue too.

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charlie-77 delf67 commented · Jun 01 2024 at 8:17 AM

I had the inverter unplugged from the bus a few times but still nothing, doesn’t show any lights at all. Should the voltage be 48v? I have 55/56v on the battery terminals.

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delf67 charlie-77 commented · Jun 01 2024 at 8:52 AM

When I said 48V, that is the nominal system voltage. Obviously under load or charge it will vary from <48V to >56V. I would expect a fully charged battery at rest to be around 52V. 55/56V does seem a little high, but I'm not familiar with the actual batteries you are using.

Regardless, the Multiplus should power up with the voltage you have, so I would assume that there is a fault with the inverter as well as the Cerbo.

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Answer 3 · 2024-05-30T18:52:55Z

derrick thomas answered · May 30 2024 at 6:52 PM

Check the serial number of the cerbo. There was a batch of cerbos that had issues on 48 volts. Yours may fall into that range. It may need replaced.

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Fideri commented · May 31 2024 at 9:33 AM

Also check if the inline fuse to the Cerbo power cable is fine.

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charlie-77 Fideri commented · May 31 2024 at 11:11 AM

Yeah all good, have checked that, definitely have power at the input plug.

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derrick thomas commented · May 31 2024 at 11:44 AM

I was able to see the serial number in your picture so I checked for you. Your serial number is among the effected units. You say that you have verified power at the plug to the cerbo, so you do in fact have a defective unit. One of the victron staff here should be able to give you direction on getting it replaced.

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charlie-77 derrick thomas commented · May 31 2024 at 12:08 PM

Ok thank you. That hopefully solves that issue then. Do you know if the fault could affect other equipment connected at the time?

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derrick thomas charlie-77 commented · May 31 2024 at 1:16 PM

Check the remote jumper in the bottom of the MP2. You may have a loose or broken jumper wire.

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Multiplus 2 System Issue

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