Cheap fuse alternative to class T

[Bluedog225]

What amp interrupt capacity do we need for a both a 12 volt LiFePO4 battery and a stack of 48 volt server rack batteries?

I ask mostly for my 12 volt system.

I see a class T gives us 20kAIC but an old fashioned plug fuse seems to give us 10kAIC. Though it’s entirely possible I’m comparing apples to bananas or I’m getting my units confused.

Wondering if these have a place in my system? Cheaper by a long way. A dim memory was that we needed to interrupt 6000 amps. But I don’t know how to calculate

Thanks

 

[Brucey]

AC versus DC rated

 

[Supervstech]

It is all about the capabilities of the battery itself.
At 12v, arc potential is reduced, so ths average 12v system cant produce over 2000aic
48v (54+v capable...) can exceed 15000...

 

[Bluedog225]

AC versus DC rated

Right in front of me. Thanks.

 

[LakeHouse]

Interrupting AC and DC are very different.
I don’t think I’d trust those ac-rated fuses for a 48Vdc system.

 

[Dynoman]

What amp interrupt capacity do we need for a both a 12 volt LiFePO4 battery and a stack of 48 volt server rack batteries?

I ask mostly for my 12 volt system.

Not an expert on fuses, but often see the MRBF fuse used for 12 Volt Lifepo4 batteries. Listed with a 10,000 AIC at 14V DC.

https://www.amazon.com/gp/product/B0017SJOH4

https://www.amazon.com/Blue-Sea-Systems-5191-Terminal/dp/B0019ZBTV4

 

[crossy]

Whilst perusing AliExpress for something else these popped up.

https://www.aliexpress.com/item/1005006442788934.html

Thoughts?

 

[DIYrich]

Whilst perusing AliExpress for something else these popped up.

https://www.aliexpress.com/item/1005006442788934.html

Thoughts?

I belive this type fuse came up in the past because they are more easily available in Australia. They have similar ratings, so should be fine. The problem is where you are buying them from. You might be getting junk that looks pretty.

 

[abeness]

The problem is where you are buying them from. You might be getting junk that looks pretty.

Apropos of your comment, DIYRich, when I built my first battery box and added a DC-DC boost converter to interface my vehicle alternator to my Victron 30A MPPT charger, I first tried inline thermal breakers such as this 50A unit: https://www.amazon.com/gp/product/B077CYP41V . I found that they tripped at less than 20A draw. Utter crap. I switched to an Eaton Bussmann 285 series and never looked back for that purpose.

Always gotta check the interrupt rating, for sure: I used an EB 187 series as primary battery protection for its switching ability in that first battery box, not realizing at the time that its 5kAIC rating for 14V may be a bit undersized for a LiFePO4 battery. Actually, I suppose for the original 100Ah it is fine, but when I upgrade to 230Ah in my next build I'll be adding a Class T. I also learned that while the Eaton Bussmann breakers actually work per spec, as thermal interrupt breakers they actually allow 110% forever, 125% for 100 secs, 150% for 30 secs.

 

[JoeHam]

Oddly enough, they use this 10k AIC on these UL certified 48V nominal batteries :

https://www.amazon.com/dp/B089TNR713

See here at the 1:15 mark :

 

[Supervstech]

Oddly enough, they use this 10k AIC on these UL certified 48V nominal batteries :

https://www.amazon.com/dp/B089TNR713

See here at the 1:15 mark :

I noticed that.
Perhaps the bms is highly rated to clamp down output in a short condition?
That is per 100Ah bank though.

 

[abeness]

Perhaps the bms is highly rated to clamp down output in a short condition?

Has anyone ever seen an interrupt current rating listed on a BMS? The general wisdom seems to be that a BMS isn't designed to protect in this manner.