Fused loop keys

Fusing is pretty standard on every other liion based application. I didn’t even invent fused loop keys.

I’m asking about the observed duration of current spikes when using a vesc 6 based esc.

I didn’t even invent fused loop keys.

Combination of two bad ideas for balancing/skates

observed duration of current spikes

Depends how thick you are… make a fire extinguisher loopkey

Yes, if the fuse blows I die, but a standard blow fuse is unlikely to randomly blow at half its rated continuous current.

imo

fuses are unnecessary, since it’s either you choose a low A fuse and risk blowing it in normal use

or set it to a point where it won’t blow, but something on the esc can die before the fuses do their job

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You do you. Plenty of people now tried to explain why it makes little sense. There’s a reason almost no one fuses their main leads.

I’ll put this topic on mute now.

Also your solder looks cold.

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Yeah, that’s my primary worry did I calculate a shorted amps wrong. If my calculation is to high, and my fuse won’t blow in the event of a short that’d be terrible. I’m less trying to protect my esc than my house from thermal runaway.

Thanks, I’ll make a new one, and set my iron hotter.

the best thing you can do is monitor cell temp and voltages, log, and alert for abnormalities, anything else is voodoo

I like the idea of using fuses in loop keys for testing new builds.

As much as I like my board. I like my body more. So rather let the board burn than risk not having stopping power.

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I don’t understand this at all…your fuse blows, that’s like someone pulling your loop key mid right. And the argument of “well it’s unlikely to blow” makes even less sense–why would you put it in there then :joy::joy:

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Just search fusing, you’ll see plenty of arguments in previous threads. I’m not really all that interested in continuing to argue about the if fusing is a good or bad idea. I’m very interested in people critiquing this method of fusing versus it’s alternatives (e.g. a fuse box, are there any others?).

seems more work than needed, no? I’m also against fusing, but if you wanna do it, just get a nice fuse holder. Less hassle to change if you blew one and survived to tell the story, also less risk of getting bad contact.

It can be almost instantaneous or it could take hours. It all depends on the cell model, its internal condition (which changes over time), the environment (ambient temp, thermal coupling to other cells, and/or any cooling), and the short-circuit current.

There’s no way to quantify it for a particular setup without destructive testing of a large number of packs and even then you will probably only have some rough numbers for the potential of forcing a cell into runaway.

It’s why we don’t want to go even near the point where it can happen…too many unknowns. :slightly_smiling_face:

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elmo

In before Mario

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Sure thing, boss.

My suggestion is that if you’re going to use a fuse, that you use a single fuse with the proper rating and not try to parallel them. And if you do that, then it would be a good way to fuse. If you were going to fuse.

I’d still always fuse the charge port either way.

Cheers

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There’s just no way to know when those fuses will blow.
I urge you to use a single fuse, not soldered to, and to check the Current vs Time (I2T) graph for the fuse. It will tell you what rating you need for the current flow you are expecting.

Be sure to also check the rerating/derating graph in order to adjust the fuse’s current rating for a higher ambient temperature. It can be a lot warmer inside a sealed enclosure, with warm cells and hot electronics, especially in Summer. That causes a fuse to blow sooner and/or at a lower current level.

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Man that was a read…so I’d like one simple clarification in the nonsense that is a fused loopkey.

You knew bms’s have discharge protection? You want to protect the board, fine. But your fuse blows, you have to redo everything. Just get a higher discharge BMS and use it as intended.

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Correct.

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I read the datasheet of each fuse when I was purchasing them. I selected based on expected current, and short circuit current (calculated from a range of possible (high capacity vs high discharge) internal resistance value’s in the possible series parallel configurations).

Here’s take two with a single 40A fuse. Unfortunately soldering is required, since I can’t fit a fuse holder in this enclosure.

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