T Class fuses...
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Robmac
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Robmac
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They also have up to 400A versions
Robmac
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For those that want to stick with Victron;
Victron Energy Lynx Class-T Power In (M10)
The Lynx Class-T Power In is a fuse module used to connect high current lithium batteries as part of the Victron Energy Lynx DC distribution system. Rated 1000A
www.12voltplanet.co.uk
merl
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Meh,
At 1min 40 he claims that the risk of not having a Class T fuse is from the lifepo4 batteries catching fire which is completely wrong. The risk of fire is from the fuse it's self starting a fire NOT the batteries.
I actually watched this video yesterday evening and spent this morning searching the net for science based facts to back up the claims and cant find any actual evidence to support the notion that a 12V system could realistically support a sustained arc for a long enough time period to start a fire.
The risk reduces as the system voltage reduces because you need higher currents at lower voltage to sustain the arc. 12 volts is very low and at this voltage you'll need to sustain several thousand amps for several seconds to start the fire at the fuse/fuse holder.
You're BMS should/would have disconnected way before then. Theoretically the BMS could develop a short circuit fault and wouldn't trip off BUT
If one the active components (FETs) in the BMS goes faulty and short circuit then the tracks on the PCB or the legs on that FET will not be able to maintain the several thousand amps needed to create the fire at the main fuse.
The voltage drop across the cables, connectors, BMS PCB tracks in the series circuit plus the voltage sag of the actual cells (remember we're talking thousands of amps here) would lead to less than 12V actually being available to sustain the arcing process.
Will Prowse backs this up here (post 27)
diysolarforum.com
He talks about Class T fuses required after 30Kw/100kw systems, a couple of posts below there's images of someone who accidentally created a short circuit on his system TWICE and the ANL fuse simply popped.
I've got a 350A ANL fuse in my lifepo4 positive lead and on the evidence I've seen so far on the subject I wont be rushing to swap it out for a Class T fuse any time soon. Maybe I'll run my fuse holder through one of these just in case the nigh impossible happens.
Certainly a cheaper option.
At 1min 40 he claims that the risk of not having a Class T fuse is from the lifepo4 batteries catching fire which is completely wrong. The risk of fire is from the fuse it's self starting a fire NOT the batteries.
I actually watched this video yesterday evening and spent this morning searching the net for science based facts to back up the claims and cant find any actual evidence to support the notion that a 12V system could realistically support a sustained arc for a long enough time period to start a fire.
The risk reduces as the system voltage reduces because you need higher currents at lower voltage to sustain the arc. 12 volts is very low and at this voltage you'll need to sustain several thousand amps for several seconds to start the fire at the fuse/fuse holder.
You're BMS should/would have disconnected way before then. Theoretically the BMS could develop a short circuit fault and wouldn't trip off BUT
If one the active components (FETs) in the BMS goes faulty and short circuit then the tracks on the PCB or the legs on that FET will not be able to maintain the several thousand amps needed to create the fire at the main fuse.
The voltage drop across the cables, connectors, BMS PCB tracks in the series circuit plus the voltage sag of the actual cells (remember we're talking thousands of amps here) would lead to less than 12V actually being available to sustain the arcing process.
Will Prowse backs this up here (post 27)
Do we still need T-Class Fuses?
Accidentally blew a class T fuse. Replaced it with ANL, accidentally blew it also, nothing spectacular. So, I am now using ANLs. But did you blow it with a worst-case short? Overload doesn't count. Short through longer higher resistance wire doesn't count. To test this correctly, you want...
diysolarforum.com
I've got a 350A ANL fuse in my lifepo4 positive lead and on the evidence I've seen so far on the subject I wont be rushing to swap it out for a Class T fuse any time soon. Maybe I'll run my fuse holder through one of these just in case the nigh impossible happens.
Lipo Safe Bag Fireproof Storage Protecting RC Lipo Battery Bag Size 18.5*7.5*6cm | eBay UK
Size: approx. Hook and Loop flap will release pressure in the event of an explosion. Type: Battery Safe Bag. 1 x Battery Safe Bag Only. Never leave charging battery unattended. Always ensure the battery is on a non-flammable surface.
www.ebay.co.uk
Fisherman
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Cheers Merl, I to have just spent the last hour looking into this and it tends to agree with what you say. I have asked David (wildebus) for his opinion. Hopefully he will give his thoughts on this.Meh,
At 1min 40 he claims that the risk of not having a Class T fuse is from the lifepo4 batteries catching fire which is completely wrong. The risk of fire is from the fuse it's self starting a fire NOT the batteries.
I actually watched this video yesterday evening and spent this morning searching the net for science based facts to back up the claims and cant find any actual evidence to support the notion that a 12V system could realistically support a sustained arc for a long enough time period to start a fire.
The risk reduces as the system voltage reduces because you need higher currents at lower voltage to sustain the arc. 12 volts is very low and at this voltage you'll need to sustain several thousand amps for several seconds to start the fire at the fuse/fuse holder.
You're BMS should/would have disconnected way before then. Theoretically the BMS could develop a short circuit fault and wouldn't trip off BUT
If one the active components (FETs) in the BMS goes faulty and short circuit then the tracks on the PCB or the legs on that FET will not be able to maintain the several thousand amps needed to create the fire at the main fuse.
The voltage drop across the cables, connectors, BMS PCB tracks in the series circuit plus the voltage sag of the actual cells (remember we're talking thousands of amps here) would lead to less than 12V actually being available to sustain the arcing process.
Will Prowse backs this up here (post 27)
He talks about Class T fuses required after 30Kw/100kw systems, a couple of posts below there's images of someone who accidentally created a short circuit on his system TWICE and the ANL fuse simply popped.Do we still need T-Class Fuses?
Accidentally blew a class T fuse. Replaced it with ANL, accidentally blew it also, nothing spectacular. So, I am now using ANLs. But did you blow it with a worst-case short? Overload doesn't count. Short through longer higher resistance wire doesn't count. To test this correctly, you want...
I've got a 350A ANL fuse in my lifepo4 positive lead and on the evidence I've seen so far on the subject I wont be rushing to swap it out for a Class T fuse any time soon. Maybe I'll run my fuse holder through one of these just in case the nigh impossible happens.
Certainly a cheaper option.Lipo Safe Bag Fireproof Storage Protecting RC Lipo Battery Bag Size 18.5*7.5*6cm | eBay UK
Size: approx. Hook and Loop flap will release pressure in the event of an explosion. Type: Battery Safe Bag. 1 x Battery Safe Bag Only. Never leave charging battery unattended. Always ensure the battery is on a non-flammable surface.www.ebay.co.uk
My 2x100ah batteries are protected by a 125a mega fuse most of these fuses are rated well above this. Although I have found one with a 150 fuse. LifePo4 batteries are far safer than normal lithium batteries used in most applications inc mobile phones etc.
Look carefully at his video, it looks like he had no fuse whatsoever before fitting this class T fuse.
I do run a 1200w victron inverter, but from what can see it makes no difference. Another issue I have is the price range is massive, just how good are the cheaper fuses against the vastly more expensive ones. I await David’s opinion, and whatever he says I will do.
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wildebus
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Meh,
At 1min 40 he claims that the risk of not having a Class T fuse is from the lifepo4 batteries catching fire which is completely wrong. The risk of fire is from the fuse it's self starting a fire NOT the batteries.
I actually watched this video yesterday evening and spent this morning searching the net for science based facts to back up the claims and cant find any actual evidence to support the notion that a 12V system could realistically support a sustained arc for a long enough time period to start a fire.
The risk reduces as the system voltage reduces because you need higher currents at lower voltage to sustain the arc. 12 volts is very low and at this voltage you'll need to sustain several thousand amps for several seconds to start the fire at the fuse/fuse holder.
You're BMS should/would have disconnected way before then. Theoretically the BMS could develop a short circuit fault and wouldn't trip off BUT
If one the active components (FETs) in the BMS goes faulty and short circuit then the tracks on the PCB or the legs on that FET will not be able to maintain the several thousand amps needed to create the fire at the main fuse.
The voltage drop across the cables, connectors, BMS PCB tracks in the series circuit plus the voltage sag of the actual cells (remember we're talking thousands of amps here) would lead to less than 12V actually being available to sustain the arcing process.
Will Prowse backs this up here (post 27)
He talks about Class T fuses required after 30Kw/100kw systems, a couple of posts below there's images of someone who accidentally created a short circuit on his system TWICE and the ANL fuse simply popped.Do we still need T-Class Fuses?
Accidentally blew a class T fuse. Replaced it with ANL, accidentally blew it also, nothing spectacular. So, I am now using ANLs. But did you blow it with a worst-case short? Overload doesn't count. Short through longer higher resistance wire doesn't count. To test this correctly, you want...
one comment on the ANL Fuse .... They are a pretty similar fuse to the MEGA fuses, but I found all (and I do literally mean ALL) the ANL fuse holders I have tried have melted! I don't know why the companies that make holders for ANL fuses seem to all use plastics that just cannot take the kind of heat that can be generated around a fuse. Don't get that generally with Megafuse holders. (I won't say never as one I fitted did go soft, but only had that happen once).
But keep an eye on that ANL Holder!
Not sure how effective that bag would really be? looks like made from a fire blanket material? It mentioned LiPo, and of course, LiPo batteries are a far higher risk and a battery type that should never be left charging unattended really. (LiPo and LiFePO4 are very different - something that is not understood in that video from what I could make out).Maybe I'll run my fuse holder through one of these just in case the nigh impossible happens.
Certainly a cheaper option.Lipo Safe Bag Fireproof Storage Protecting RC Lipo Battery Bag Size 18.5*7.5*6cm | eBay UK
Size: approx. Hook and Loop flap will release pressure in the event of an explosion. Type: Battery Safe Bag. 1 x Battery Safe Bag Only. Never leave charging battery unattended. Always ensure the battery is on a non-flammable surface.www.ebay.co.uk
Admin
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Agreed.Meh,
At 1min 40 he claims that the risk of not having a Class T fuse is from the lifepo4 batteries catching fire which is completely wrong. The risk of fire is from the fuse it's self starting a fire NOT the batteries.
I actually watched this video yesterday evening and spent this morning searching the net for science based facts to back up the claims and cant find any actual evidence to support the notion that a 12V system could realistically support a sustained arc for a long enough time period to start a fire.
The risk reduces as the system voltage reduces because you need higher currents at lower voltage to sustain the arc. 12 volts is very low and at this voltage you'll need to sustain several thousand amps for several seconds to start the fire at the fuse/fuse holder.
You're BMS should/would have disconnected way before then. Theoretically the BMS could develop a short circuit fault and wouldn't trip off BUT
If one the active components (FETs) in the BMS goes faulty and short circuit then the tracks on the PCB or the legs on that FET will not be able to maintain the several thousand amps needed to create the fire at the main fuse.
The voltage drop across the cables, connectors, BMS PCB tracks in the series circuit plus the voltage sag of the actual cells (remember we're talking thousands of amps here) would lead to less than 12V actually being available to sustain the arcing process.
Will Prowse backs this up here (post 27)
He talks about Class T fuses required after 30Kw/100kw systems, a couple of posts below there's images of someone who accidentally created a short circuit on his system TWICE and the ANL fuse simply popped.Do we still need T-Class Fuses?
Accidentally blew a class T fuse. Replaced it with ANL, accidentally blew it also, nothing spectacular. So, I am now using ANLs. But did you blow it with a worst-case short? Overload doesn't count. Short through longer higher resistance wire doesn't count. To test this correctly, you want...
I've got a 350A ANL fuse in my lifepo4 positive lead and on the evidence I've seen so far on the subject I wont be rushing to swap it out for a Class T fuse any time soon. Maybe I'll run my fuse holder through one of these just in case the nigh impossible happens.
Certainly a cheaper option.Lipo Safe Bag Fireproof Storage Protecting RC Lipo Battery Bag Size 18.5*7.5*6cm | eBay UK
Size: approx. Hook and Loop flap will release pressure in the event of an explosion. Type: Battery Safe Bag. 1 x Battery Safe Bag Only. Never leave charging battery unattended. Always ensure the battery is on a non-flammable surface.www.ebay.co.uk
The BMS in LiFePO4 batteries will deal with short circuits.
If the BMS did fail, then as you say, the FETs (Transistors) would most likely burn out rapidly.
If the BMS fails, then fusing is the next line of defence.
I have four batteries, and because they can produce a high current when in parallel, they are each fused individually.
The drama Lithium Ion images in this video are NOT LiFePO4, which is much safer than other Lithium-ion chemistries.
merl
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It's a charging bag David that's used when charging lipo batteries, if you're competing in the radio controlled model realm charging lipo batteries for cars, aircraft, boats and drones you MUST charge your lipos in one of these fireproof charging bags in case something happens and you inadvertently overcharge them. When lipo's go they REALLY GO! They are a real scary fireball, if one of these charging bags can contain a set of lipos it'll laugh in the face of a 12V arcing fuse/holder.
wildebus
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he literally had nothing before and I assume didn't think he needed anything before a comment on a previous video.
Fisherman
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So he goes from having no fuse (which is clearly wrong) to advocating this type C fuse.
I would rather listen to what you, David, and Phil state.
Another thing that annoyed me was the exploding van, that type of thing puts a big doubt in my mind.
But I have learned something I did not know Merl, that the BMS is the first point of safety and not the fuse. But then that only illustrates how little I know about vehicle electronics.
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merl
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The fear is that under a direct short circuit the fuse will rupture with very high current and the melting metal in the fuse at very high temperatures will create a plasma and that plasma will then conduct the electricity continuously in the form of an arc, basically the same as you get when you arc weld metal. It's proposed that the arc will last long enough to start a fire at the fuse holder.
When I was a teenager we used to use car batteries and jump leads to do arc welding. It's a while ago now
cry but from memory we used 3 car batteries in series so 36V in total, the ground was actually taken from the positive end of the chain and the negative was taken from one of the busbars on top of the 3rd battery, by moving this jump lead up and down the lead bus bars you could fine tune the voltage and hence current depending on what thickness metal you were welding and how flat the batteries were at the time, we always used somewhere between 24 and 36V, at the time we were using proper high quality jump leads of about 75mm csa. There's a few videos on the net showing how to do this too and the videos bear out exactly what I remember and that is you simply couldn't weld with just 1 12V battery, you couldn't make a sustaining arc with 12V even if you tried. I think the chances of it happening by accident in a fuse holder of a camper with a 12V system are somewhere between highly unlikely and virtually impossible. I'd be more cautious with a 24V system though.
I posted a link to guy who was blowing things up with 100 car batteries wired in parallel before
At first he has them all in parallel so a 12v system, yep he melts stuff and there's lots of sparking but NO sustaining arcs, it's not until he changes the wiring configuration at about 7 mins in to give 60V that you get sustaining arcs and he's actually able to make a DIY plasma cutter. Scary 5hit mind
When I was a teenager we used to use car batteries and jump leads to do arc welding. It's a while ago now
cry but from memory we used 3 car batteries in series so 36V in total, the ground was actually taken from the positive end of the chain and the negative was taken from one of the busbars on top of the 3rd battery, by moving this jump lead up and down the lead bus bars you could fine tune the voltage and hence current depending on what thickness metal you were welding and how flat the batteries were at the time, we always used somewhere between 24 and 36V, at the time we were using proper high quality jump leads of about 75mm csa. There's a few videos on the net showing how to do this too and the videos bear out exactly what I remember and that is you simply couldn't weld with just 1 12V battery, you couldn't make a sustaining arc with 12V even if you tried. I think the chances of it happening by accident in a fuse holder of a camper with a 12V system are somewhere between highly unlikely and virtually impossible. I'd be more cautious with a 24V system though.I posted a link to guy who was blowing things up with 100 car batteries wired in parallel before
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merl
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Yeh mines a cheap plastic thing too, It's been in for a few years now and fitted when I used to have Lead Carbons, I do deliberately run what most would regard as an 'oversized fuse' for just this reason (A350A fuse at about 140A maximum current) simply to keep the volts across the fuse low and the heat generated down, so far so good but thanks for the heads up
Fisherman
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This is what happened to my mega fuse and holder, soon after installation.
I think it was due to a loose connection.
I replaced the holder with a victron unit and used it to the max with no issues.
Obviously the 125A fuse was blown and had also to be replaced.
This happened when using a 1kw hairdryer, which has since been used with no issues.
I think it was due to a loose connection.
I replaced the holder with a victron unit and used it to the max with no issues.
Obviously the 125A fuse was blown and had also to be replaced.
This happened when using a 1kw hairdryer, which has since been used with no issues.
wildebus
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was a strange one, that. Used the same brand many times with no problems, but got a few Victron ones afterwards to compare.
The key is a tight connection for sure. Seen plenty of melted fuses and holders on installations - both aftermarket and OEM ones. Problem with connections made on wiring in a moving vehicle ... vibration is not a friend
Blade Fuse
Blade Fuse Holder by David, on Flickr
fusemelt by David, on Flickr
colinm
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Threads like this usually have me going down a rabbit hole, and this was no exception.
So what have I been watching?
Several vids showing LiFePo4 batteries being dead shorted with very little sign of ill effects, but more disturbingly some 280Ah LiFePo4 'leisure' batteries having BMS overcurrent set to 850a,
So what have I been watching?
Several vids showing LiFePo4 batteries being dead shorted with very little sign of ill effects, but more disturbingly some 280Ah LiFePo4 'leisure' batteries having BMS overcurrent set to 850a,
guerdeval
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I agree with everything stated here but I’d like to hear barryd’s opinion before finally making my mind up