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Fuses?!?
#1
Sooo. I've build a portable sound system and this just happened. I've build a pack of 18650 batteries (11s3p) with a total voltage of 46,2V. I've used a car fuse for the amplifier, but all of a sudden - The amp started bursting fire. I cut the connection between the battery and amp and the fire went out.

Now. I thought the fuse would've blown, but apparently not. I've used a 15A car fuse, but wondered if I should find something else, now that I'm working with 48V and not 12V. I'm from Denmark, Europe and would like a British or Chinese supplier (If you intend on linking items I should go for)

The amp is rated at 2x500w but probably only use 250w pr channel at peak.
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#2
What voltage is the amp rated for ?

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#3
I am more curious about the amplifier… I’ve been in the audio game for some time and have never really come across amps with a native voltage that high. Most always 12v or AC voltage. You sure you didn’t need to build a 3s11p pack?

In any case, always look at the voltage rating for the fuse… most are rated for 32V DC. Exceeding that voltage you could end up with arching.
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#4
The car fuse is 32VDC, Thats most likely not the problem. You bought a chinese amp that was crap is my guess Tongue

15A at that voltage is 700W. doesnt take much to blow it. I would have used a 5A fuse at most!
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#5
Voltage range is not too relevant in a fuse. It's the current that matters.

Maybe the amplifier was designed for a lower voltage ? In that case, if powered from more, it will burn no matter the fuse you use.
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#6
Car fuse might arc, ie not cleanly blow, if their rated voltage is exceeded.

We need to know what voltage the amp supply rating is (and/or make & model)!

The batteries might have lower impedance than the amp is used to resulting in higher current peaks in the transistors, etc if driving speakers hard.
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#7
The amp is Chinese but they're pretty good quality.
https://www.parts-express.com/sure-elect...--320-3369

The board can handle the voltage just fine. The battery pack is a pack I build myself.

I think what might've happened is a short connection. I wasn't around myself when it happened but my friend told me that a fire the size of a thumb bursted out next to one of the speaker outputs on the board. The plus and minus cables looked like they've been shaken out of the terminal over time, and might've touch eachother.

Back to the fuse. The amp was on without music running when it happened. I've held parties twice a week since new year with full volume for 2 hrs atleast and never experienced this or any other problems. Should I get a lower-rated fuse to avoid a fire hazard in the event of a short? Right now it's a 15A fuse but I might look for 10 or 8A instead.
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#8
Is the 15a fuse the recommended size?
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#9
Its nice that all are discussing the fuse, but since the fuse did NOT blow it had not anything to do with his fire. Whatever this caused, its not the fuse.

Is a Class D amplifier, what about the speakers, have they been connected, is that possibly necessary ?

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#10
So it seems shorted output is the likely cause.
As often happens, the output stage "blew to protect the fuse"! Ie the junctions in the transistors are less thermal mass than the fuse & blow first.
Like daromer suggests maybe check the spec for the recommended fuse.
Using proper connectors like XLR or "speakon" speaker connectors helps avoid shorts.
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