EG4-LL missing breaker

[Will Prowse]

Its clearly a breaker.

It's used as a switch. Did you not see my previous post about what I discussed with the engineers? An actual DC switch will cost more than a breaker. You guys would be surprised which company told me this. Signature solar was actually using DC breakers before everyone else was.

 

[Will Prowse]

Its better but I would prefer to see verbiage that clearly indicates that the device is not intended to provide over-current protection.

No, its a breaker.

Then they should clearly label so that expectations are set correctly.

Well it does provide OCP as I stated multiple times before. Please do not respond to me if you do not read what I wrote, it is quite frustrating. A breaker is used for OCP and can be used as a switch.

A breaker can serve as a switch. How is this so hard to understand?

What expectations? The breaker protects the conductor from breaker to BMS. And it's rated for DC so you can state that it's doing that as well.

But like I've said multiple times now, these engineers use them as a cheap switch. That's it. You can use components to accomplish multiple tasks. It is serving as a switch and a breaker.

 

[Will Prowse]

Scenario:
User welds the FETs in the BMS closed by failing to prime the inverter capacitors correctly as above ^.
The BMS still passes current so the user carries on as if nothing happened.
From this moment forward, the breaker is the first line of defense against an internal short and the last line of defense against an un-protected short downstream.

He who says "never" has eternity to be proven wrong.

I completely agree and the reason all of these stupid batteries have DC breakers is because I told them to. I got extremely pissed off and I yelled at everyone and forced them all to have DC breakers. I don't understand what point you're trying to make. I am telling you what the engineers had in mind and the use case. What you are saying here is not useful to anybody at all.

 

[Will Prowse]

The majority of 12 volt lithium iron phosphate batteries on the market do not have any breaker at all and you are not criticizing them. I can list off 50 batteries right now off the top of my head that have the BMS output leads connected directly to a terminal. How about you start criticizing those? I was the one staying up late asking these companies for the data sheet on every breaker that they had before I gave a recommendation. I told them that no matter what they should still have a DC circuit breaker even though it costs more. That was because of me. I don't understand how you don't realize how it can be used as a switch as well and that was what they were thinking of when they designed it.

If it wasn't appropriate these batteries wouldn't have a UL listing either. It can be used as a switch or breaker or both It doesn't matter.

 

[John Frum]

It's used as a switch. Did you not see my previous post about what I discussed with the engineers?

Yes I did.
The fact is the device in question is a breaker.
If the engineer only intends it to be used as an administrative disconnect then it needs to be clearly labeled.

An actual DC switch will cost more than a breaker.

Especially since its intended use is redundant to the on/off switch.
I fail to see the logic of incurring this added expense.

You guys would be surprised which company told me this.

Are you going to share?

Signature solar was actually using DC breakers before everyone else was.

Good for them.

 

[John Frum]

I don't understand what point you're trying to make.

Not for my lack of trying.

What you are saying here is not useful to anybody at all.

Sure it is.

 

[John Frum]

What you are saying here is not useful to anybody at all.

I'm not saying that.
Maybe you have misunderstood my comments.

 

[Will Prowse]

Yes I did.
The fact is the device in question is a breaker.
If the engineer only intends it to be used as an administrative disconnect then it needs to be clearly labeled.

Especially since its intended use is redundant to the on/off switch.
I fail to see the logic of incurring this added expense.

Are you going to share?

Good for them.

It's both. I said that multiple times.

It's not redundant. The models without BMS on and off switch needed a switch. So they used a breaker as a switch. Very simple logic.

No I'm not going to share because I hate that company. You could figure it out if you thought about it haha.

 

[robby]

Well it does provide OCP as I stated multiple times before. Please do not respond to me if you do not read what I wrote, it is quite frustrating. A breaker is used for OCP and can be used as a switch.

Yeah Will we get what your saying but in engineering terms you would be completely wrong.
As @John Frum stated to you with the distinction of "Administrative Disconnect".
Example your in the Hospital on a Ventilator. The Power Switch on the Ventilator cannot shut down because of a short circuit because then the Alarm systems to warn the nurses would also be shutdown. A Switch should only change states by means of human intervention while a breaker can kill power completely on it's own. This may not seem like a huge difference in battery operation but it is life and death in a design of mission critical equipment in most industries. I would not want a battery pack that did not have it's OCP on a completely separate power interrupt system from the one that keeps the monitoring system running.

 

[Will Prowse]

I'm not saying that.
Maybe you have misunderstood my comments.

I'm saying once again that it is a breaker that is being used as a switch and a breaker. Before they were not DC rated and I told multiple companies to make them DC rated and now they are.

 

[Will Prowse]

Yeah Will we get what your saying but in engineering terms you would be completely wrong.
As @John Frum stated to you with the distinction of "Administrative Disconnect".
Example your in the Hospital on a Ventilator. The Power Switch on the Ventilator cannot shut down because of a short circuit because then the Alarm systems to warn the nurses would also be shutdown. A Switch should only change states by means of human intervention while a breaker can kill power completely on it's own. This may not seem like a huge difference in battery operation but it is life and death in a design of mission critical equipment in most industries. I would not want a battery pack that did not have it's OCP on a completely separate power interrupt system from the one that keeps the monitoring system running.

My computer room light switch does not say on or off and it does not have a administrative disconnect label on it. Why does it not have one?

I also have a combiner box that does not have that labeled either.

I also have another battery with a switch on it that's not labeled.

Why are all of these batteries and products passing without this label? What am I missing here

 

[Will Prowse]

On trophy battery it says on and off. Is that sufficient or not

 

[Will Prowse]

Yeah Will we get what your saying but in engineering terms you would be completely wrong.
As @John Frum stated to you with the distinction of "Administrative Disconnect".
Example your in the Hospital on a Ventilator. The Power Switch on the Ventilator cannot shut down because of a short circuit because then the Alarm systems to warn the nurses would also be shutdown. A Switch should only change states by means of human intervention while a breaker can kill power completely on it's own. This may not seem like a huge difference in battery operation but it is life and death in a design of mission critical equipment in most industries. I would not want a battery pack that did not have it's OCP on a completely separate power interrupt system from the one that keeps the monitoring system running.

What are they legally required to do for these battery systems? Why are these battery systems passing UL and other certificates with the breaker being used as a disconnect?

 

[John Frum]

On trophy battery it says on and off. Is that sufficient or not

IMO if the breaker is dc rated for sufficient voltage and breaking capacity it is fine.
If any of those criteria are not met then it should be labelled.
An AC only breaker should either be replaced or labelled as I've said.

 

[John Frum]

My computer room light switch does not say on or off and it does not have a administrative disconnect label on it. Why does it not have one?

Because its clearly not a breaker.
There should be a breaker upstream though.

 

[robby]

What are they legally required to do for these battery systems? Why are these battery systems passing UL and other certificates with the breaker being used as a disconnect?

They pass because the breaker can disconnect the power to the terminals and the BMS has it's own power switch. The normal EG4 and most other rack mount batteries have it correct but that bastard version of the EG4LL has no real OCP except for the prayer that the detection circuitry works and shuts down the Mosfets. My experience has been that MOSFET protection circuitry is typically pretty reliable at doing this when you have sudden shorts but they are terrible at doing it when you run them near the extreme limits for extended periods of time.
The junctions get hot and they eventually fuse together even though you have not exceeded the maximum current limit to trip them.
Cooling issues can make this a lot worst.

 

[John Frum]

Because its clearly not a breaker.
There should be a breaker upstream though.

Similar concept here.

 

[Will Prowse]

IMO if the breaker is dc rated for sufficient voltage and breaking capacity it is fine.
If any of those criteria are not met then it should be labelled.
An AC only breaker should either be replaced or labelled as I've said.

That's what myself and everyone else agrees on. And all of them are DC rated. Please share a battery here that is still using an ac breaker.

 

[Will Prowse]

They pass because the breaker can disconnect the power to the terminals and the BMS has it's own power switch. The normal EG4 and most other rack mount batteries have it correct but that bastard version of the EG4LL has no real OCP except for the prayer that the detection circuitry works and shuts down the Mosfets. My experience has been that MOSFET protection circuitry is typically pretty reliable at doing this when you have sudden shorts but they are terrible at doing it when you run them near the extreme limits for extended periods of time.
The junctions get hot and they eventually fuse together even though you have not exceeded the maximum current limit to trip them.
Cooling issues can make this a lot worst.

I actually agree but unfortunately a lot of batteries are not going to have that. I just got another 48V battery today from roypow and it doesn't have one either. And it can handle 300A discharge.

I'm going to add my own t class fuse to it.

 

[John Frum]

That's what myself and everyone else agrees on. And all of them are DC rated. Please share a battery here that is still using an ac breaker.

I'm talking about all the ones in the field that are ac rated or dc but not fit for purpose.

 

[Will Prowse]

Because its clearly not a breaker.
There should be a breaker upstream though.

Upstream where? On the cell terminals? Not sure where upstream you could mount a break. Can you show us a schematic of a better design?

 

[Will Prowse]

I'm talking about all the ones in the feild that are ac rated.

Which ones are those? I eradicated them from the market (the ones I knew of). Signature solar actually had DC rated from the beginning. There are other companies that I didn't do reviews on that I forced to have a DC rated breaker. Please share who is using ac rated breakers.

 

[John Frum]

Upstream where?

At the start of the branch circuit.

Can you show us a schematic of a better design?

Do I really need to in light of the explanation above? ^

 

[Will Prowse]

Trophy and a few others had to spend more money for the larger DC rated breaker. This was over a year ago when this discussion was occuring. Who is not using DC rated breakers now?

 

[John Frum]

Which ones are those? I eradicated them from the market (the ones I knew of).

If there are none in the field than none need to be addressed.
Good job Will!