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Graham Walmsley avatar image
Graham Walmsley asked

Connecting dual pylon tech battery stacks

My initial build will contain a stack of 4 x Pylon Tech US3000C batteries connected in parallel to a multiplus-ii 230V 8000VA, with the module link cables connected and the CAN port connected to the Cerbo GX so it can talk to the BMS. Due to the rated current of the connector cables (120A) and the recommended charge/discharge being 148A for the stack (4 x 37A) I am going to run 4 cables to a Lynx Distributor (positive and negative from both the top and bottom modules so it doesn't exceed the cable rating) and so I can easily fuse each 120A positive cable.

All good so far.

Now to my question.

When I add the second stack of 4 modules (4 separate DC cables going to the Lynx Distributor), do I just carry on with the link cables (bottom module of stack 1 to top module of stack 2) and treat it as one large battery bank, or do I run a second CAN cable to the Cerbo GX and it somehow deals with the dual battery stacks, or is the PylonTech hub required?

My thinking is treat it as a stack of 8 as they are all still in parallel (US3000C can have up to 16 modules in a single stack), just via the Lynx Distributor, but I can't find any documentation either way.

Any advice gratefully received.

cerbo gxBMSPylontech
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3 Answers
Alexandra avatar image
Alexandra answered ·

@Graham Walmsley

You will have nice current sharing using the distributor.

The GX wont care how it is physically piled up. And as long as you have connected the correct order of data cables, the "stack" will be seen as 8. (and then by extension 16).

I have not connected 16 yet but in the other models if you connect 9 it only addresses 8 in CAN anyway. So it is more of an address/software limitation.

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Graham Walmsley avatar image Graham Walmsley commented ·
Thanks for your response, glad I was on the right track
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Pablo avatar image
Pablo answered ·

@Graham Walmsley

These are the pics of my current battery setup (14 pylontech US3000C+cerbo)

The top and bottom units of each of the two stacks are connected to a distribution busbar.

Both stacks are connected (for management) as a single stack of units (lanport1 to lanport0 of the next unit and the latest one connected to the BMS can port of the cerbo-gx).

the connection between battery bank and cerbo must be done with a Victron “battery BMS can-type A”.

Hope it’s useful.4c70f79e-274a-4f22-a36d-4ccd805cd26f.jpegfab80745-d5f0-4a03-bd48-2a8a6c6e7e9e.jpeg


4c70f79e-274a-4f22-a36d-4ccd805cd26f.jpeg (2.7 MiB)
fab80745-d5f0-4a03-bd48-2a8a6c6e7e9e.jpeg (2.6 MiB)
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Graham Walmsley avatar image Graham Walmsley commented ·
That is very useful, thank you


Is the cable between the two stacks just a normal Ethernet cable?


Do you have any isolators on the two stacks or just rely on the off switches on the front? If you do, which ones?


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Pablo avatar image Pablo Graham Walmsley commented ·
Yes, same as the uplink ones. In fact, it’s another uplink but longer.

there is no isolation between stacks and the busbar. The on-off switches were advised by pylontech as enough.

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alaskannoob avatar image alaskannoob commented ·

@Pablo any issues with balancing or the batteries in between the top and bottom batteries getting less current?


I'm trying to decide how best to wire up my Pylontech batteries and I'm thinking about the Victron Wiring Unlimited guide about parallel batteries:

parallel-issues.jpeg

Which recommends to connect like this:

parallel-wiring.jpeg

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parallel-issues.jpeg (46.0 KiB)
parallel-wiring.jpeg (46.0 KiB)
Pablo avatar image
Pablo answered ·

@AlaskanNoob

I’ve not detected any balancing issue.

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