46khw of batteries: Best wiring method?

[luisfcosta]

Greetings!

I am looking for hints on the best wiring scenario for 18 x BYD 24V 3kw LiFePo4, to feed a ~10Kw 48V hybrid inverter (RS485/CAN capable).
Got these battery modules cheap from Battery Hookup a few months ago and I learned these cells get out of balance very frequently.

At this stage I am considering 2 scenarios - what is your take?

1) Attach an 80-100A 48V 16S BMS (CAN/RS485 capable) to 2 x BYD units (series) and repeat this setup to build 9 x 48V modules (could the inverter maintain a conversation with 9 units?)

2) Parallel all individual cells for cell balancing, skip the BMS, monitor battery health with individual cell monitor and configure the inverter to manage the pack with SOC / voltage / etc.

Thank you for our thoughts

 

[Samsonite801]

Helped a friend on this same exact setup recently.

Go exactly with option: 1)

My friend has 16 packs, so each dual pack (making a 16s pack), were then paralleled to make 8x 48v packs, connected to a Solark 12k.

I don't know about communication as his wasn't compatible with Solark, but just connected to each BMS via smartphone app for now (we might switch his BMS's to other brand later).

But theoretically, if you have the right BMS's, the inverter is only connecting to one (master) BMS, and that BMS comms with all the rest (slaves) using a backend CAN bus network. Some of them might use an RS485 or a CAN bus frontend link, going from the inverter to the master BMS, and then connect via other cable port from that master to the backend network to each slave BMS via CAN bus (daisy-chained) in a string.

 

[luisfcosta]

Helped a friend on this same exact setup recently.

Go exactly with option: 1)

My friend has 16 packs, so each dual pack (making a 16s pack), were then paralleled to make 8x 48v packs, connected to a Solark 12k.

I don't know about communication as his wasn't compatible with Solark, but just connected to each BMS via smartphone app for now (we might switch his BMS's to other brand later).

But theoretically, if you have the right BMS's, the inverter is only connecting to one (master) BMS, and that BMS comms with all the rest (slaves) using a backend CAN bus network. Some of them might use an RS485 or a CAN bus frontend link, going from the inverter to the master BMS, and then connect via other cable port from that master to the backend network to each slave BMS via CAN bus (daisy-chained) in a string.

Awesome! I may be on the right track then.
I will look into multiple BMS' and the concept of master/slaves

 

[luisfcosta]

Maybe something like this: https://www.batrium.com/collections/kits/products/watchmon-core-k9
(Original idea from this post)

 

[Samsonite801]

Maybe something like this: https://www.batrium.com/collections/kits/products/watchmon-core-k9
(Original idea from this post)

Yeah, you'll have to check if Batrium is comms compatible with your specific inverter brand, because RS485 or CAN bus is just a hardware protocol, says nothing about the programming language operating on top of that.

Also, Seplos is another brand BMS which supports the idea of master/slave BMS... Just note that they sell two different models, one having RS485 frontend network, and other with CAN bus frontend network (both models have CAN bus backend network for the inter-BMS comms..

 

[Samsonite801]

Solar Assistant on an RPi might support having multiple BMS/batteries added to it (with single-connect BMS's, if not using the master/slave architecture, probably also can support BMS with master/slave architecture as well in SA), of course if it is a BMS that SA can support in the first place.