House burned down
- Thread starter Jejochen
- Start date
Zwy
Emperor Of Solar
Then why are you disagreeing with me?
The comment is not directed at you, it is for those that don't use a Class T fuse for this application. You on the other hand, have looked at the situation and made the right choice.
Zwy
Emperor Of Solar
They are so proud of the specs the datasheet won't load for me.
B-Mod
Solar Enthusiast
ricardocello
Watching and Learning
Try this link: https://www.belfuse.com/resources/datasheets/circuitprotection/ds-CP-0AFG-series.pdf
Not a bad fuse, but only 10 kA AIC, as compared to 20 kA for the Class T.
Also 150 VDC instead of 300 VDC for JLLS (125 VDC for JLLN).
JLLN - Littelfuse
JLLS - Littelfuse
Last edited:
B-Mod
Solar Enthusiast
Here ya go.......
Product specs
Product specs
hwy17
Anti-Solar Enthusiast
I am sold on one hypothesis, which is a case to case short within a pack and the fire was unstoppable from there. But I've been trying to avoid coming into OP's thread and arguing with the fuse theory because of the sensitive nature of the situation. His fire inspector has identified the fuse and I understand how he needs to proceed with that.
Same case with the other fire. Circuitry was originally identified as the cause, and hotly debated, but I suspect it was case to case as well. Also not gonna try and press that OP on it either.
DPC
Solar Enthusiast
Mostly I'm giving you the gears.
There are 3 or 4 different types of J fuse you can get that range form time delay to fast for protecting drives with large currents and high available faults....
Why I bring this up....
I remember these big exide battery chargers I used to fix I think they were 300 or 400 amps.
Diodes as big as beer can ( well close )
Some used a T some had J installed.
We used them relatively interchangeably on those chargers ( to be very specific ).
J was rated for 600 volt T I don't think it was rated above 250 or 400 volts dc or something
My point is its a stoutly build fuse with a lot of interrupt capacity and the ability to deal with the heat of clearing a fault
These are some fuses I used on the K 1050E Kiruna both in the main converter and chopper drives ( one fed form a trolley line one a large battery bank to a DC drive and traction motor )
Even has a little striker in it to indicate its blown ( a common feature in an industrial fuse )
Those are god dam expensive, a good fuse is not a cheap thing....
In a previous post in this thread I saw some stuff like this.
I've seen this on light vehicles and they do not inspire much confidence in me.
I helped a mechanic make a fuse holder for one of these a couple of weeks ago actually, for a solar system and I did not give it much thought because, its not my cottage.
Now back to those Exide chargers.
I made some fuse holders for them too to convert them from T to J
I made it out of nice thick piece of glasstic stand off from a Silvania motor starter switch with some red brass bolts .
Never had a problem...
But those light duty fuses I see like the one above is really light duty looking.
I'm not going to say you should pick one fuse over another since T seems to be the standard but I am going to say use a good semi conductor fast acting fuse and a decent stout holder to contain and arcs or burn through.
Fusing is not a place to cut corners.
Aliexpress and Ebay are full of cheap Chinese fuses and fake parts too.
Just because something says it a certain thing you should question if its Chinese and a really good price.
No I did not get the T to J conversion blessed by an engineer.
I just did it because we were short of T fuses at one point and I know the J would work and no one was looking over my shoulder.
I did talk to some guys up in engineering years later over coffee and they were not impressed.
I'm going to go talk to that mechanic and see if I can talk him out of what he was going to do.
And making something out of something handy.
Might use a J fuse lots of them around... Ahem.
( Added later after reading some others posts... I might find some old stock T fuses in the car barn where the last electric Loco was used the spares cabinet... might still be there, might be a battery charger of some sort with fuse holders I can strip.... I'm going to heed the advice myself and look for T, although I think the fast J is probably fine )
But a proper fuse and holder are a major safety concern.
Don't anyone listen to anything I say!
Its all 100 percent opinion form some guy on the interweb with both an opinion and anal sphincter everyone has at least one of those.
Last edited:
PotusGobbleBottom
Corn Pop was a bad dude.
Has anyone tested this? How much current flows at 3.4v between unprotected cells. Some one needs make some controlled measurements.
Ampster
Renewable Energy Hobbyist
I don't follow your logic. What kind of fire source would start spontaneously? I understand your theory of melting wires but usually that is caused by over current which fuses are designed to protect against. So in my logic that circles back to failure of the fuse which caused the wires to heat up.
Tulex
Solar Wizard
I'm just saying it's too easy to blame the fuse. If they could prove it, that would be great, put my mind at ease. But, I have 48 cells in 3 DIY batteries, soon to get doubled. I'd like to know it wasn't something else that caused it being masked by the fuse. I don't have any idea what could have been the cause of a fire, but nobody knows why the fuse blew either.
robbob2112
Doing more research, mosty harmless
Case to case short. So neg connected to neg. But also pos connected to neg with a bus bar. This cell is going to discharge super quick and overheat. This pops the vent. At the same time the battery it is part of drops by 3.4v. Now go back to my last post about what happend when a cell is shorted. The current will blow the fuse, but it will also heat the wire and fuse to the point of open flames. Now the vented hydrogen ignites.
All of this happens in just a few minutes.
And at 4am there was likely only one thing on with enough draw to affect things.
OP has a hottub whichis between 30 and 50 amps. He talks about hooking it up near the end of his powerwall thread. My hottub circulates the water all the time and only heats when the temp is low. Older hottubs use a timer to limit electricity use to certain times of day.
Mine is a small one with a 5kw heating element in it at 240v. But it also has 2 motors, a 1/2 hp that spins all the time and a 2hp motor that powers the jets.
All that said I doubt the 'event' was in any way load related.
Makes me wonder if there is an upper limit on parallel batteries. With every battery protected by a class C or any other ignition safe fuse that can extinguish the arc it is pretty safe. And having batteries in fully enclosed metal cases separate from each other would also help.
Last edited:
Daddy Tanuki
Solar Wizard
I have class T fuses and Midnight breakers, and I havealot of questions about this. not the install, the OP did a great job. I think he would have been better with class T, but something happened somewhere to cause the mega fuse to pop. I stopped using Mega fuses when I stopped installing 12 volt stereos... that was like 25 years ago.
something that is 48 nominal I would have never tried with a fuse that started out as a 12 volt itemand was "upgraded" to 24 and then 48. the space inthe quench chamber is not large enough. just my opinion of course.
that being said, something casued a heck of a lot of current to pass through that fuse and that could have been the start of it. the fuse might have caused a secondary hot spot or it might have been the primary. I bet it was secondary, and the real culprit was elsewhere.
Daddy Tanuki
Solar Wizard
same here:
An error occurred while processing your request.
Reference #97.38da387d.1714612216.a2bcbf19
Daddy Tanuki
Solar Wizard
real easy way to fix this issue. by nylon cased cells like winston, sinopoly or calb. no worries about shorting cases, and I still have as of yet not heard of a battery bank fire caused by them.
B-Mod
Solar Enthusiast
crossy
Solar Addict
Is a 10kA breaking capacity sufficient for such a pack one wonders?
The 200A MCBs fitted to my Liyuan 280Ah packs are also 10kA.
I'd possibly want something with a bit more capacity as the last chance saloon.
I'm looking at RT36-00 fuses as being more available here than the preferred beasties, 100kA. These have been discussed in other fusing threads.
The fuse being an under-dimensioned component is an obvious issue, and something happened that caused it to attempt to interrupt the circuit, with a fault current well above its rating. (Generally pointing to a dead short.)
The problem with calling the fuse the root cause (blindly) is that we fail to learn what the underlying issue was that caused the failure. The other obvious missing component is automated string-level disconnect, which adds credence to the theory that a battery issue on one string caused the fire... but it could have been an inverter issue causing a dead short on the DC bus.
I think most of the people here agree that you need at least 20kA interrupting capability on a string fuse, and really as high as you can get. This is a reminder/lesson to them that "supplemental" fuses can still be a hazard if they are not properly dimensioned.
My gotcha is was there something else likely to be going on that we should be aware of in designing, building, and maintaining our systems in order to reduce the risk of fire. Currently I am leaning to fewer parallel strings in UL packages and more systems for my peace of mind, but if this is a rodent or inverter issue then a different strategy would be warranted.
robbob2112
Doing more research, mosty harmless
Well well, found these on aliexpress cheap enough with fuse holder to order a few samples to evaluate. Ordered a 125amp and a 200amp version along with a holder for each. I'm afraid I intend to destroy them both in the process.
Brett V
Mad Scientist
I know Victron uses the Mega Fuse and for some reason, the word of the holy blue cult is treated as gospel. But the class-t fuse is much more appropriate for these batteries. You get what you pay for.
