Busbar Size

[addision]

I had a issue with my new EG4 batteries and tech support suggested that I put them through a series of charge/discharge cycles in open loop since I am not sure if I had them withing 1 volt of each other when I put them into service. Since I am going open loop for a while I decided I may as well just connect up my previous Fortress battery as well and get them all in sync now instead of doing this all over again.

Now the question is what Busbar do I use. I see the Victron Lynx Distributor is rated at 1000A. Does anyone know if this will accept a 4/0 conductor? I know the sheath thickness has something to do with it, but someone may have experience and can let me know if it fits easily or not at all.

Seeing as I have now 3 EG4 powerpro batteries at 200A max, and I want to add in a Fortress 18.5k also at 200A. Will this device handle the current for this system? I had a 4/0 going to my Fortress, but the EG4's use a 2/0 conductor.

I have plans to add a 4th EG4 soon. What would be my options then? I really want a busbar that has a cover. I did see the ones at Signature Solar, but they are only rated for 600A.

I am not against making one myself, and I read that the size is based on the cross section of the conductor used. Would this be adding the area of all the conductors together to determine the size of the Busbar?

 

[FilterGuy]

The busbar size can be speced based on load instead of battery capability. If you have a 1200W inverter, the continuous load is no more than 12000/48 = 250A. Consequently, a 250A or 300A busbar is fine even though the batteries could produce much more. However, there needs to be fusing or breakers on the batteries.

 

[DougfromdaUP]

The busbar size can be speced based on load instead of battery capability. If you have a 1200W inverter, the continuous load is no more than 12000/48 = 250A. Consequently, a 250A or 300A busbar is fine even though the batteries could produce much more. However, there needs to be fusing or breakers on the batteries.

I think you meant to say the continuous load is no more than 1200/48 or 25 Amperes.

Too much coffee maybe.

Might want to use 1200/45(low voltage cutoff)/.85(inverter efficiency = 31 Amps.

 

[ChrisG]

The Lynx PowerIn and Distributor can handle 22mm diameter. Believe 4/0 is ~12mm

 

[FilterGuy]

I think you meant to say the continuous load is no more than 1200/48 or 25 Amperes.

Too much coffee maybe.

Might want to use 1200/45(low voltage cutoff)/.85(inverter efficiency = 31 Amps.

Oops. I meant to use a 12KW inverter in the example, but your math looks correct for a 1200W inverter. And yes, putting inverter efficiency in the calculation is a good idea.

Either way, the point is that the bus bar can be selected based on load, not battery current capacity....as long as the battery has proper over-current protection. If you want to be super conservative, the busbar should be sized for the sum of the OCPDs of the batteries, but in any real world that is overkill if the OCPDs are selected on Battery capability. If the total capability of all the batteries is significantly lower than what the load will demand, put in smaller OCPDs.