Connecting Vebus bms and Cerbo to 800va multiplus with only one vebus port

DIY
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1

Hi, I am looking for the correct way to connect my older victron lifepo4 batteries (bat512900400) to a system with a cerbo gx and multiplus 800va. I have a vebus bms (v1). The problem is that the multiplus only has one vebus port and as far as I can gather I should be connecting both the bms and the cerbogx directly to the multi. I’ve read that the cerbo specifically should not to connect the bms remote panel port on a vebus bms v1.

Is this combination of devices possible? Or is it possible to use these older lifepo4 batteries with a vebus bms v2? The v2 is designed to connect the cerbo to the remote panel port, but im not sure it’s compatible with the batteries i have. They are non smart, but do have the three pin communication leads that connect to vebus bms v1.

The only other option I can see is to connect the vebus bms v1 to the cerbo, and not directly to the multiplus, but I have no idea if it will function that way!

2

Which firmware versions do you have?

Otherwise, just give it a try; if necessary, you may have to perform firmware updates if it doesn’t work.

3

@Bones83 I have used it in this configuration with a cerbo as opposed to DMC without any problem. You can also consider a simple RJ45 splitter if you have a spare.

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4

Thanks for the replies, have you used ot those way with a vebus bms v1? I only check because in the cerbogx manual it specifically states…

"VE.Bus systems with Lithium batteries and VE.Bus BMS (v1 only)

The following applies only to the VE.Bus BMS V1, not to be confused with its successors, the VE.Bus BMS V2 or VE.Bus BMS NG.

GX device connection

Connect the GX device to the MultiPlus/Quattro VE.Bus socket, not to the Remote panel socket.

Alternatively, connect to one of the Multis/Quattros in the system.

Combining MultiPlus/Quattro with a VE.Bus BMS and a Digital Multi Control is possible. Simply connect the Digital Multi Control to the RJ45 socket on the VE.Bus BMS labelled Remote panel."

I had no idea I could use a splitter like you suggested on this kind of communication port. I had assumed the two ports on a bigger multiplus were in some way separate communication channels.

Regarding the firmware, are you asking about the multiplus firmware version?

5

So I have taken your advice to try it out and see with mixed success.

I installed a vebus bms assistant onto the multiplus. The multiplus is running firmware version 414.

With all the system components connected to the cerbo; multiplus and bms on vebus, mppt on vedirect, I observe…

The multiplus works more or less as expected; if I disconnect the 3pin communication cable from the battery, the multiplus shuts down. When I reconnect the cable, the multiplus powers on again. All good so far…

However, the mppt continues to charge. Am I correct in thinking that a break in the 3pin communication cable should also halt mopt charging?

I have dvcc enabled but the bms is not visible in the controlling bms selection list. There is also no serial number for the bms in the multplus serial numbers list.

Another thing I have noticed is that the multiplus is not using the mppt current to improve vebus soc.

So although it is shutting off the multiplus under some circumstances, I believe the communication is still not correct.

If anyone has experienced these problems before, I’d love to hear about it and try to get the system communicating well.

Thanks for reading, any input greatly appreciated!