John Frum
Tell me your problems
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What mess?
Please be specific.
Single vs. Multiple Class-T Fuses
- Thread starter AHTrimble
- Start date
Please be specific.
James Showalter
CEO, EG4 Electronics, Signature Solar founder
we have never used AC-Only Breakers.
We already went around on this, you say that this means we don't stand behind the breaker but how could that be if it specifies sizing breakers only if not included with the product? this is a categorically oxymoronic way to read this
John Frum
Tell me your problems
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I disagree.
James Showalter
CEO, EG4 Electronics, Signature Solar founder
You are all over this forum telling people these are AC breakers and in some comments you say you would remove the breaker and replace it with whatever janky fuse you wanted to pontificate on. pls get that off the web. we don't want to be dealing with jacked-up server rack batteries in our tech support dept.
James Showalter
CEO, EG4 Electronics, Signature Solar founder
well we got you the spec sheet, you can get the language teacher
Also states that the current protection is supplied by BMS. I know you don't agree that the BMS should be trusted, but it's designed to work before the breaker. I don't see what the issue is. It has two methods of protection. They can claim that BMS is responsible. I don't see the safety issue.
James Showalter
CEO, EG4 Electronics, Signature Solar founder
the BMS will always trip before the DC breaker in posted video we show how much time the breaker takes
Gosh this is going no where just like in the past arguments. The proof is there. Manual states current protection is provided by BMS. Looks fine to me.
What's the issue John
What's the issue John
TorC
Solar Enthusiast
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Yep, right there on PDF page five, manual page four. In a manual of this kind, expected to be gone over by lawyers, I would first read that statement the same way John does, as a weaselly way to escape ensuring proper protection, which has now been demonstrated untrue. The statement about the BMS providing protection is not nearby, that I can see.
The included breaker is, or at least is now, properly rated to protect the battery. That recent picture Will posted makes it abundantly clear what it's capable of, regardless of what the battery manual does or does not say. At this point, I'm inclined to think the whole statement is unneeded, as the breaker is sufficient to handle a short circuit as a failsafe, even if the BMS can be expected to do the job first and provide better protection.
John Frum
Tell me your problems
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I don't trust any FET based BMS to protect against a dead short as I've said repeatedly in this thread.
Since I've seen some evidence that the breaker is dc rated with sufficient breaking capacity at sufficient voltage I will trust the breaker.
I have suggested that Signature solar should reword the manual to make clear that they stand behind their breaker.
"The included breaker is not a guarantee of battery protection." -- https://signaturesolar.com/content/documents/EG4/EG4-LL 48V-24V Manual-1.2.0.pdf
Please read back a bit and you will see that I'm not saying anything new here.
Let's leave it up to signature solar then. I don't see a safety issue so if you kindly suggest it, maybe they will make the changes at their own discretion.
Can we talk about class t fuses now?
Can we talk about class t fuses now?
I think of it as choosing wisely where to spend money. People have budgets, often far smaller than they would like. And there's a whole list of reasons why someone might end up with a system that isn't fused sanely. Such as a rackmount battery rack where the batteries have questionably rated breakers, or running batteries to a Lynx several feet away from the batteries, etc.
So while in theory "each bat needs a class T" is a nice safe idea, it's also a spendy one (especially after the fact). Thats why I'd really like to focus on actual numbers and testing. And if need be prove that the breakers are not suffecient and dangerous to include and perhaps force the manufacture's hands to install a suitable one at the factory, OR put in something that is JUST a manual disconnect and mark it as such. Right now we're paying for something that may not work and many of us pay for additional OCP (and IF class T is truely overkill per-bat, OVER paying too).
If you, or anyone, does test that. IMHO Welder's mask and protective clothing and trigger it from a distance, juuuuuust in case theres an arc flash.
Personally I'm between the "T class per server rack battery" (esp the "only" 100AH ones) and "the BMS is enough".
Regarding your T-class per rack. I do very much agree, but having them so far from the racks feels iffy to me. A mitigating factor would be insuring that unfused positive leads have additional physical protection while being separated from negative/ground leads.
I can confirm I have the same breakers on My V2s. I think the manual still says they are not OCP, but I'll double check
My V1s have a 4kA DC rated breaker.
So are per bat fuses over-kill in my case and just wasted voltage drop? I'm keeping the class-t from the rack either way.
As written the manual reads (at least the PDF version linked elsewhere in this thead) as unambiguously saying that OCP MUST be provided outside of the battery. Now, perhaps I'm dumb but thats how I understood it from months ago.
Here's my terrible non lawyer approved rewording attempt:
"Note that the breaker only protects the battery and correctly sized wire. When combining batteries in parallel appropriate OCP must be provided. In no case should 'wire, conductors, busbars, or any device' be used where the OCP is higher than the safe rating. Consult the manual and/or relevant code in your area. Local code may also require additional or specific OCP."
What length bolts do you need? I may have some long enough left over from my earlier PowerIn modifications and I would be happy to send them to you. Probably some leftover nuts and flat washers as well. I only have 4 copper split washers though and I would want to hold on to those.
Thanks for the offer. I already ordered some. I’ll let you know the proper length after I get them and if they’re too long, I have a grinding wheel.
What about SOK batteries? Have they sent/told you anything about their breakers?
I spent a bunch of time on the Victron community site and saw some very interesting info, some of which was from Victron reps. Basically; 1) the BMS protects the battery for OCP, faster than fuses or CBs, (matches what Will was saying) 2) Class-T's were on battery banks as close to the busbar as possible, 3) the CNN's inside the Lynx Shunt were acceptable in Victron wiring diagrams for system OCP. Then I went to a company's site that has hundreds of installs under their belt, looked at their wiring schematics and they go with 1) Class-T's were only on battery banks also, 2) they had no problem with MRBF's to protect the battery to busbar wiring...wait for it...because they also said that the battery BMS provides OCP for the battery itself.Thanks for the offer. I already ordered some. I’ll let you know the proper length after I get them and if they’re too long, I have a grinding wheel.
I do like your idea of the Class-T inside the PowerIn based on what these companies are talking about. It would be another line of defense protecting all non-shorted batteries in the bank from the shorted battery should its BMS fail. And it would protect the other system components from the shorted battery as well.
Are you going to be using the Lynx Shunt with a CNN fuse? Or a Class-T for the entire bank without a Lynx Shunt?
I understand it might be an overkill, but there’s a few members here that are very insistent and have me paranoid.
And some don’t even want Batteries in their house. 
So as I posted, two paralleled batteries (100Ah x 2) per class T fuse. And another class T fuse from the Power In bank to the inverters.
No shunt planned currently.
Yeah, that whole "very insistent" thing got to me a little as well...then tunnel vision kicked in.I understand it might be an overkill, but there’s a few members here that are very insistent and have me paranoid.
So as I posted, two paralleled batteries (100Ah x 2) per class T fuse. And another class T fuse from the Power In bank to the inverters.
No shunt planned currently.
I am not technically savvy enough to know one way or the other...so I went back to Victron for their take on it. They were pretty clear. Then I went to someone who has done hundreds of installs for their take. I figure that those guys have a universe more technical knowledge than me. And with all those installs...if something wasn't right with their methodology it would have shown up by now. And they both backed up Will's comment about the battery OCP provided by the BMS. Trifecta of sound practical knowledge
I really like that you are stepping outside the box and actually making something. I can appreciate a DIY guy who is hands on. And who knows...maybe you are really on to something! Think patents...and millions
I am really thinking MRBF's on the batteries. But for now I just have to get this upgrade finished...then take a week off from everything!
But please keep me updated on the whole PowerIn / Class-T thing...it sounds really interesting.
{edit} If you get a minute...Why no shunt? What are you going to do for monitoring?
wiseacre
Solar Addict
You and me both ?I understand it might be an overkill, but there’s a few members here that are very insistent and have me paranoid.
Your modification of the Lynx Power-In also has me intrigued.
Be nice to see a separate post on how you went about it from beginning to end.
I have a lot on my plate, so solar is kinda on the back burner for now. But will post pictures when I’m finished.Yeah, that whole "very insistent" thing got to me a little as well...then tunnel vision kicked in.
I am not technically savvy enough to know one way or the other...so I went back to Victron for their take on it. They were pretty clear. Then I went to someone who has done hundreds of installs for their take. I figure that those guys have a universe more technical knowledge than me. And with all those installs...if something wasn't right with their methodology it would have shown up by now. And they both backed up Will's comment about the battery OCP provided by the BMS. Trifecta of sound practical knowledge
I really like that you are stepping outside the box and actually making something. I can appreciate a DIY guy who is hands on. And who knows...maybe you are really on to something! Think patents...and millions
I am really thinking MRBF's on the batteries. But for now I just have to get this upgrade finished...then take a week off from everything!
But please keep me updated on the whole PowerIn / Class-T thing...it sounds really interesting.
{edit} If you get a minute...Why no shunt? What are you going to do for monitoring?
The guy who I bought the batteries from also thought I was going overboard and mentioned that the BMS is enough. But where is the BMS manufactured…CHINA!? (So are the breakers)
So you be the Judge…
I guess when it comes to any potential of a house fire, I open my wallet, if anything just for a piece of mind.
I may add a shunt someday, gonna see if I really need it first.
I have a 250A class T right immediately after each 16S pack. I have a disconnect switch that I won't throw without loads shut off first at the inverter.
I thought about breakers but I don't trust all these cheap ones on Amazon, and the should be good ones are more expensive than fuses, so...
I thought about breakers but I don't trust all these cheap ones on Amazon, and the should be good ones are more expensive than fuses, so...
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