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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

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3 Answers
Paul B avatar image
Paul B answered ·

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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Paul B avatar image Paul B commented ·
The bottom 3 plugs seem to be miss alligned, as they usually line up to the markings
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charlie-77 avatar image charlie-77 commented ·
Thanks for the reply, I had taken the power plug out at this point to test the voltage, no lights still once plugged in though.
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Rob Fijn avatar image
Rob Fijn answered ·

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 avatar image charlie-77 commented ·
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 avatar image delf67 charlie-77 commented ·

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 avatar image charlie-77 delf67 commented ·
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 avatar image delf67 charlie-77 commented ·

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 avatar image charlie-77 delf67 commented ·

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 avatar image delf67 charlie-77 commented ·
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 avatar image charlie-77 delf67 commented ·
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 avatar image delf67 charlie-77 commented ·

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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derrick thomas avatar image
derrick thomas answered ·

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 avatar image Fideri commented ·
Also check if the inline fuse to the Cerbo power cable is fine.
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derrick thomas avatar image derrick thomas commented ·
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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