EG4 Battery Rack Breakers???

[WattAboutThat]

I currently have Two EG4 Battery Racks, each with 6 48V Batteries 100Ah of storage per battery, so 600Ah storage per rack.

I don’t understand how to calculate the DC breaker size i would need to place on each rack.

I understand that each individual battery has a breaker, but I want to be able to protect each entire rack, and also have the ability to isolate one rack, leaving the remaining rack functional, in case I would need to service a specific rack.

Signature Solar has this

https://signaturesolar.com/nader-dc-circuit-breaker-60v-200amp-with-enclosure/

60V 200A breaker - but how do i know/calculate
that 200A is sufficient???

currently there will be 2 18kPV inverters
that can max charge and max discharge at 250A to and from the batteries (per inverter),
and I intend later to add 2 more inverters.

I can not find the Amps (as opposed to Ah)
for the batteries, but assume that it is the Amps being drawn from inverters, or supplied by inverters that determines the amps.

if that assumption is correct, then i could have
up to a max of 500A (2 inverters x 250A) in or out, (if later add 2 more inverters, then 1000A),

so 200A breaker would seem too small per battery rack. And I have not been able to find larger Amp DC breaker similar to above.

Sorry to continue with idd questions
but this is my next issue of confusion.

Please advise.

Thanks

 

[timselectric]

Overcurrent protection is based on 125% of conductor rating. Conductor size is based on maximum amperage expected.
So, size your conductor and protection according to the most current you need to flow.
I oversize everything to be able to carry full current, at diminished capacity.
In other words, I can run wide open. With less than half of my batteries connected.

 

[Lt.Dan]

If a 200a breaker is too small for you, you should be looking at Class T fuses instead. They're not as easy to disconnect for service to a rack, but will handle the current much much better.

 

[WattAboutThat]

 

[Liz@lowcountry]

I have a similar situation, 6-EG4 in a rack. 4/0 cable to 12KW growatt off grid. Sig solar keeps telling me 125amp double pole nader breaker is adequate. Thoughts?

 

[timselectric]

I have a similar situation, 6-EG4 in a rack. 4/0 cable to 12KW growatt off grid. Sig solar keeps telling me 125amp double pole nader breaker is adequate. Thoughts?

The 12k can draw up to 250a at 48v.
The double pole Nader breaker is rated for 125a per pole. With the bus bar that combines the two poles, you are covered for the 250a.

 

[Liz@lowcountry]

Thank you, any suggestions on how i can connect my 4/0 wire to the 2/0 lug?

 

[timselectric]

Thank you, any suggestions on how i can connect my 4/0 wire to the 2/0 lug?

Change the lugs to 4/0 lugs.

 

[Liz@lowcountry]

Jumper isnt big enough, i got a 4/0 lug from ilsco

 

[timselectric]

Might need to make a bigger bus bar.

 

[Watts Happening]

If a 200a breaker is too small for you, you should be looking at Class T fuses instead. They're not as easy to disconnect for service to a rack, but will handle the current much much better.

In theory there wouldn’t be a reason you’d “have” to disconnect one. Flip each battery breaker off, then shut off anything up stream.

In my case with a Sol-Ark 15k I’d trip the 200a battery breaker in the unit as well.

 

[Justdr5]

I was looking at a similar solution. I emailed signature solar to confirm I could use the same CB as a disconnect and they responded with this:

Each line, from the Quattro and the charge controller, would need their own breaker. Using it as a disconnect is fine as it is meant to always be closed; however, as we have had some customers do this, we have to remind you that this breaker is NOT to be used as an on/off switch for the battery bank. For the line and load direction, this is does not matter since DC current flows in only one direction.

So now I'm a bit confused. I think maybe they didn't understand a quattro is a charger and an inverter. But they clearly state not to use this as a disconnect (on/off) to the battery bank.

 

[Lt.Dan]

I was looking at a similar solution. I emailed signature solar to confirm I could use the same CB as a disconnect and they responded with this:

Each line, from the Quattro and the charge controller, would need their own breaker. Using it as a disconnect is fine as it is meant to always be closed; however, as we have had some customers do this, we have to remind you that this breaker is NOT to be used as an on/off switch for the battery bank. For the line and load direction, this is does not matter since DC current flows in only one direction.

So now I'm a bit confused. I think maybe they didn't understand a quattro is a charger and an inverter. But they clearly state not to use this as a disconnect (on/off) to the battery bank.

I think they dont want you to use it as an off switch while under heavy load?

That's how I interpret it.

 

[Liz@lowcountry]

The 12k can draw up to 250a at 48v.
The double pole Nader breaker is rated for 125a per pole. With the bus bar that combines the two poles, you are covered for the 250a.

Well i am still dealing with this, i was told fine stranded wire cannot be terminated using a mechanical lug. (Supplied with nader breaker) it can only terminate directly on the copper with the screw provided. The hole looks like its 1/4” which wont work with 3/8 ring. Any suggestions? Toss the nader break ?

 

[pvgirl]

Well i am still dealing with this, i was told fine stranded wire cannot be terminated using a mechanical lug. (Supplied with nader breaker) it can only terminate directly on the copper with the screw provided. The hole looks like its 1/4” which wont work with 3/8 ring. Any suggestions? Toss the nader break ?

Crimp a properly sized lug to the wire connect it using the bolt.

 

[timselectric]

That