Best Way to Join Two 8S Packs With Two 8S BMS's

[guidecca]

I need to join my two 8S Modules with two 8S BMS's to power a 24V system. How do you do it and what should it produce? Fuse both positive leads separately and join positive leads to positive bus bar. Separate shunt for each module's negative lead and join to negative bus bar? 1200W solar panels, 40A Epever solar charge controller, 24V Samlex 2200W Inverter Charger, (16 ) 280Ah LifePO4 cells divided into blocks of four cell. Those are the main components. Are the copper bus bars worth the trouble or can I get by with the nickel plated bus bars that came with the batteries.

 

[John Frum]

What is the ampacity rating of the BMS?

 

[John Frum]

I need to join my two 8S Modules with two 8S BMS's to power a 24V system. How do you do it and what should it produce? Fuse both positive leads separately and join positive leads to positive bus bar. Separate shunt for each module's negative lead and join to negative bus bar? 1200W solar panels, 40A Epever solar charge controller, 24V Samlex 2200W Inverter Charger, (16 ) 280Ah LifePO4 cells divided into blocks of four cell. Those are the main components.

That looks like 2x 4s packs.

 

[guidecca]

What is the ampacity rating of the BMS?

100A 24V 8S Overkill BMS's

 

[guidecca]

That looks like 2x 4s packs.

There are four packs with four cells in each pack. I'll create the 8S inside the box.

 

[John Frum]

Will you have a shunt?

 

[guidecca]

Will you have a shunt?

Yes. A simple shunt. Do I need a separate shunt for each box of 8S?

 

[John Frum]

Make 2x 8s packs each with its own bms and connect them to the main busbars as depicted in this textual topology diagram.
UPDATED: fix clerical errors in diagram.

 

[John Frum]

The battery positive cables and the battery negative cables should be the same length so that they have approximately the same resistance.

 

[guidecca]

I wonder if I am over my voltage limit with those solar panels. If so, can I run them in parallel with fuses to a breaker?

 

[John Frum]

I wonder if I am over my voltage limit with those solar panels. If so, can I run them in parallel with fuses to a breaker?

What are pv the voltage details of the solar charge controller and the panels?
Permutations are 6s1p, 3s2p, 2s3p and 1s6p.
Where p > 2 you need over-current protection on the strings.

 

[John Frum]

Since you have smart BMSs the shunt is redundant.

 

[John Frum]

Updated topo.

 

[Steve_S]

 

[guidecca]

You guys are something else. The project is building itself. Here is the back of one of the PV's. I've been dead in the water for awhile.

 

[John Frum]

Since the EVO has terminals for an external charge source you could connect the battery and charge controller directly to the EVO.
This avoid having main busbars.
Depends on being able to fit two lugs onto the EVO's main terminals.

 

[John Frum]

You guys are something else. The project is building itself. Here is the back of one of the PV's. I've been dead in the water for awhile.

Still need a product link for the solar charge controller.

 

[John Frum]

Which exact panels do you have?

 

[guidecca]

What are pv the voltage details of the solar charge controller and the panels?
Permutations are 6s1p, 3s2p, 2s3p and 1s6p.
Where p > 2 you need over-current protection on the strings.

1. What is the VOC of the panels?
VOC is 48.59v (VOC ± 5 % at STC)

2. What is the max voltage of the SCC?
Max. PV open circuit voltage is 150V at minimum operating environment temperature and 138V at 25 degrees Celcius environment temperature

Max. PV Array Power is 3120W/24V

 

[guidecca]

Which exact panels do you have?

Still need a product link for the solar charge controller.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.conermex.com.mx/manuales/controladores/Manual_TracerBN.pdf&ved=2ahUKEwi-kMCzmrbcAhXjqFkKHeOLAecQFjAAegQIBRAB&usg=AOvVaw0USroEAKFdZU7kHRUzPF3x

Its the model 4215Bn