House burned down
- Thread starter Jejochen
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I have that exact one on my 200ah Chins 48v battery.
BarracudaBob
Harvesting free photons from clean fusion
I am adding one to every battery, Great idea.
Those fuses are rated to interrupt 2,000A at 58VDC maximum. A bolted fault with parallel strings could exceed that rating, which is what happened in the OP's case; the Mega fuses are rated 1,000A at 58VDC IIRC.
A Class-T fuse in contrast is rated to interrupt 20,000A at 125VDC maximum.
ricardocello
Watching and Learning
Correct, however there are also 70V MEGA fuses rated at 2.5kA (littelfuse sf51).
But Class-T is the way to go 20 kA@125VDC.
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Suijkerbuijk
I cannot be held responsible for this information.
I agree
But the fuse wat i use my self will not burn
No plastic house need it .
This is one of the reason we use it in boats.
Its direct by the battery and if a kabel break thanks to the water go up and down .
The systeem wil be save .
Do not forget a boat is steel (well what i have 12ton of steel)
Sorry my Engelse is not that great.
And i'm dyslexie (look up if you need to know what that is )
Is a good use for cars to boats and wy not use it in a house .
Just a safety by the battery.
But normal if a lipo4 is not diy model.
The bms had shut it down .
Other thing i use is a victron battery protect unit .
But that can only handel 220 amps continu on 12/24volt systeem so its not for use in a house.
Model Victron battery protect bp-220 .
Its just a extra save systeem i use so that i do not need the bms .
The systeem go off for that the bms shutdown to low volt or if thare is a problem by overload .
My lipo4 do 150amps continu and about 600amps for 10 sec .
After 3 time over the limit the systeem shutdown.
And i have to restart from the app .
The bms is for me a last save systeem .
But i life on the boat its my home.
So i have to have a good systeem .
If i'm on the sea (North Sea ) i'm alone if somtings happens.
No fire truck no help nothing .
ScrotpusGobbleBottom
Corn Pop was a bad dude.
You are right, Your english isnt great, but it is perfectly fine. I understood exactly what you wanted to say.
Good job! Have a good day! (my english isnt "great" either)
It wasn't the plastic that likely caused the OP's fire, it was the plasma arc that was caused by a fault greater than the interrupting capability of the fuse. The plasma arc then ignited an explosive atmosphere. For batteries installed in a confined space like a boat this is still a concern. (An arc fault can melt metal, so the difference between metal and plastic is insignificant. A ceramic fuse that is exposed to a current higher than its interrupting rating will not be able to break an arc.)
The MRBFs are a great solution for providing protection close to the source, but if you have more than 1-2 strings they might not be sufficient to interrupt a full-current fault. One way to work around that is to have the MRBF mid-string, and have the Class-T fuse at the common busbar for each string. This way if the MRBF fails to open you still have the Class-T as backup. If you have a fault between the battery and Class-T you still have some level of fuse protection.
_voltmeter_
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the mega fuse was not the problem, the not existing bms per paralel battery bank was.
of course something else can ignite a explosive atmosphere if a cell vents hydrogen.
a class t fuse would not have saved his house
at all, again and again.
a fuse does not protect the battery a bms is needed on each paralel bank!
You need both the BMS and the fuse for different reasons. We are in agreement on the OP's situation given the information available. (BMS logs would have been useful in determining just how quickly the battery failed and if the correct protection mechanism was a BMS alone or if a fuse was required to isolate the string.)
Personally, on a boat I wouldn't consider anything but a UL9540 battery installed fully within the manufacturer's parameters. I am not aware of a solution yet that is well suited to marine applications over ~15kWh on a single bus.
Suijkerbuijk
I cannot be held responsible for this information.
A fully boat that use full electric systeem and not fuel.
Have systeem that go up 230 volt and even higher to 600 volt dc to ac .
Like a house its more easy to use the same volts so you only have to switch dc to a ac systeem.
So all what is use in house can be used in a boat.
You have ac and dc breakers .
The electrical engine room is close of from water .
Ground go in to the water .
Than a house
In the usa you only have 120 volt and 220 volt for high volt systeem. (400volt ??)
In the eu we have 243 volt and 400 volt in our home
And we can even go higher if we like after a license to 600 volt.
Our basic house fuse from the energy Company is
1x40 amps if it a old house or 3x16 amps .
This is the basic.
Than we can pay extra for 3x25amps after that we go to the max and that is 3x35 amps.
After new ground kabel if you pay the cost.
3x45 amps and up.
3x35 amps is about 24kw of power.
Not that strange we go full electric in the eu by the year 2035.
No gas for heating .
Full electric cars and boats.
Electrische heating systeem by a groundheat pomp systeem .
Reason in my country 4 new nukepower systeem are going to be beult.
But we go of topic.
_voltmeter_
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i agree.
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GummiSolar
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You can use either connection. There are two connections so you can put boxes in parallel
dd_agripharma
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Translation:
I agree with your points. However, the fuse I use personally does not burn out. There is no need for a plastic housing. This is one of the reasons we use it in boats. It is connected directly to the battery, and if a cable breaks due to the water's movement, the system remains safe. Remember, my boat is made of steel, weighing 12 tons.
I apologize for my poor English. I also have dyslexia (you can look it up if needed).
This setup is suitable for cars and boats, so why not use it in a house? It provides safety by the battery. Normally, if a LiFePO4 battery is not DIY, the BMS will shut it down.
Additionally, I use a Victron battery protection unit. However, it can only handle 220 amps continuously on a 12/24V system, so it is not suitable for house use. The model I use is the Victron Battery Protect BP-220. This is an extra safety system I use, so I do not rely solely on the BMS. The system shuts down if the BMS detects low voltage or an overload problem.
My LiFePO4 battery can handle 150 amps continuously and about 600 amps for 10 seconds. After exceeding the limit three times, the system shuts down, and I have to restart it from the app.
For me, the BMS is a last-resort safety system. Since I live on a boat, which is my home, I need a reliable system. If I am out at sea (North Sea), I am alone if something happens—no fire truck, no help, nothing.
Jojoplumber
New Member
Can you just use breakers? Isn't it the same thing just you can reset it?
Brucey
Solar Wizard
A quality DC breaker like a Midnite MNEDC250 with 250A capability and 50,000 AIC rating will generally be in the $90+ range. It is nice to be able to use one as a battery disconnect as well.
ScrotpusGobbleBottom
Corn Pop was a bad dude.
If the amp draw is on the graph, that means it came from the inverter. Right??
An internal short on the battery wouldnt register any amp drain on a shunt or BMS in a paralleled group. It would simply be voltage rise or drop.
Consumerbot3418
Fitting square pegs into round holes... for fun?
This thread gave me a wake-up call, and has me taking another look at safety. I figured the LFP chemistry was fairly safe. Also figured the MEGA fuses in my Victron Lynx would be adequate (and they likely were, when my battery config was 12V nominal, instead of 48), and that I have the BMS as a backstop.
Schneider XW Pro PDP came with a 250A DC breaker that looks suspiciously similar to the Midnite one. Both manufactured by Carlswitch? But I think I might need something for the Sunny Islands I'm presently setting up to test. Not sure, but I don't think the DC disconnect on the front of SI is a legit breaker. Anyway, I got real excited when I found this link in another post--$47 for the Midnite 250A breaker! Too bad altEstore went out of business/isn't taking orders...
Can't decide if I should do away with the Lynx entirely, and just put a MRBF or class T on each 100ah parallel bank... or replace the MEGA fuses in Lynx with the Littelfuse 70V version. Those "only" have 2500 AIC. Blue Sea MRBF specs 2000 AIC @ 58V. Class T is the best, but the price once you've bought one and one of those fuse blocks...
The little DIN mount DC breakers do 6000AIC and are pretty affordable, so maybe one of those per parallel bank is a good compromise? Not sure how I'd go about wiring that close to each terminal, though.
Brucey
Solar Wizard
Carlingtech and C.B.I make the breakers for Midnite (and others).
robbob2112
Doing more research, mosty harmless
Well, my 2 cents and worth that -
CBI makes midnite breakers - same design but to a higher spec according to the midnite marketing
Fuses - ANL, Mega, MRBF, etc can all fail explosively when they blow. - Class T in ignition safe enclosures contain the failure internally and the enclosure contains anything that might leak out.
If you just have a small install of a couple of batteries MRBF is a good start. When you get to 3 or more where 2 batteries can dump into one the class T becomes more appropriate. The more batteries the more it moves into required territory.
For a permenant home install I would bite the bullet and have a class T on every single battery near the bus bar.
The Victron class T lynx is an only OK thing IMO - so far as I can tell it doesn't contain the sparks if there are any or keep explosive gasses away from the fuse. I could be wrong on this as I don't have one in hand to play with. Personally like the Blue Sea/Eaton ignition safe mount with the latching levers. They take up space and they only hook up by cable but they are very well designed.
CBI makes midnite breakers - same design but to a higher spec according to the midnite marketing
Fuses - ANL, Mega, MRBF, etc can all fail explosively when they blow. - Class T in ignition safe enclosures contain the failure internally and the enclosure contains anything that might leak out.
If you just have a small install of a couple of batteries MRBF is a good start. When you get to 3 or more where 2 batteries can dump into one the class T becomes more appropriate. The more batteries the more it moves into required territory.
For a permenant home install I would bite the bullet and have a class T on every single battery near the bus bar.
The Victron class T lynx is an only OK thing IMO - so far as I can tell it doesn't contain the sparks if there are any or keep explosive gasses away from the fuse. I could be wrong on this as I don't have one in hand to play with. Personally like the Blue Sea/Eaton ignition safe mount with the latching levers. They take up space and they only hook up by cable but they are very well designed.
Suijkerbuijk
I cannot be held responsible for this information.
I agree.
For small battery like 12 volt 50/250ah i use a mrbf fuse.
2x24 volt battery in series i will still use a mrbf fuse on both plus pools
If more battery in series go to a bus bar i us t-fuse (48 volt and up)
Still my personal 2 cents are this.
For 2 battery in series or parallel both will be fine with mrbf .
If one of them blow, the series connection is broken.
So no power
On parallel one will shutdown and the other will have the full load and a good bms will shut that battery down.
A good mrbf fuse is make from ceramic
(Same stuf like a bougie is make )
But are fake ones on the market
For small battery like 12 volt 50/250ah i use a mrbf fuse.
2x24 volt battery in series i will still use a mrbf fuse on both plus pools
If more battery in series go to a bus bar i us t-fuse (48 volt and up)
Still my personal 2 cents are this.
For 2 battery in series or parallel both will be fine with mrbf .
If one of them blow, the series connection is broken.
So no power
On parallel one will shutdown and the other will have the full load and a good bms will shut that battery down.
A good mrbf fuse is make from ceramic
(Same stuf like a bougie is make )
But are fake ones on the market
Jesus H Christ! Thank goodness you and your family are okay! That is scary. I'm also sorry for all of your belongings and keepsakes that you likely lost as well. That is brutal.
Consumerbot3418
Fitting square pegs into round holes... for fun?
I think my takeaway is that if you need more capacity, but already have sufficient ampacity, it's probably better to just avoid paralleling entirely.
It gives me an idea--doesn't look like a product that exists, but couldn't a DC boost converter be used to safely shuttle power back and forth between banks that would otherwise be parallel? I'm thinking about something similar to those equalizers designed for 12v batteries that are in series (to keep 48V made of 4S 12V internally balanced). Seems like it'd be a huge safety gain...
robbob2112
Doing more research, mosty harmless
You typically need a 3 to 5 volt difference for a boost converter to do what you describe. In the lead acid world they use a battery isolator. In the lithium world as long as everything is done correctly the load current and charge current are split evenly between parallel batteries.
Hedges
I See Electromagnetic Fields!
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Sunny Boy Storage, an HV AC coupled battery inverter, does that with 3x battery inputs.
Actually, the battery I have for it (LG RESU-10H) does that internally: 150V native battery, bidirectional DC/DC to 400V.
This does have some issues, especially maintaining an island grid for AC coupled GT PV inverters. I think their hybrid Sunny Boy Smart Energy gets around this by sharing HV DC rail between battery and PV. Same could be true of other HF hybrids (if they also had separate battery controllers.
It comes for free when inverter is packaged with battery, like Encharge and Tesla PowerWall.
This could also be accomplished with grid-forming inverter having high current battery, and multiple AC coupled batteries.
But probably not too bad with BMS and disconnect per battery. Protection by disconnecting, just can't connect and bring on line until voltage is very similar so no inrush. Couple of us plan to do that with one JK BMS per 16s battery, not sure yet how they aggregate current requests for the inverter.
We don't know for sure what happened with OP's system. I'm thinking contactor per battery string would have let BMS prevent overcharge of a cell. Don't know if it had shunt per string or only one shunt for whole bank.
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